Ninth Nanoforum Report:

Nanotechnology in

Aerospace

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February 2007

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Nanotechnology in Aerospace

www.nanoforum.org February 2007

Editor: Ineke Malsch, Malsch TechnoValuation Authors: Janusz D. Fidelus, Witold Lojkowski, Laboratory of Nanocrystalline Materials, Institute of High Pressure Physics, Polish Academy of Science; Małgorzata Lewandowska, Faculty of Materials Science and Engineering, Warsaw University of Technology; Dariusz Bielinski, Faculty of Chemistry, Technical University of Lodz; Ineke Malsch, Malsch TechnoValuation (chapter 2) Holger Hoffschulz, VDI-TZ GmbH; Ineke Malsch, Malsch TechnoValuation (chapter 3) Aline Charpentier, CEA-LETI – Minatec; Ineke Malsch, Malsch TechnoValuation (chapter 4) Kshitij Singh, Mark Morrison, IoN; Ineke Malsch, Malsch TechnoValuation (chapter 5, 6) Ana Proykova, MCG, University of Sofia; Ineke Malsch, Malsch TechnoValuation (chapter 7, 8)

Acknowledgement: Reviewers: Thierry Jamin, CNES (chapter 4) Christien Enzing, TNO; Paul E. Rempes, Environmental Assurance, Boeing St. Louis, MO, USA (chapter 7), Patrick Lin, Nanoethics; Jürgen Altmann, University of Bochum (chapter 8).

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Nanoforum is a thematic network funded by the European Commission's under the Fifth Framework Programme (Growth programme, grant number G5RT-CT-2002-05084). The contents of this report are the responsibility of the authors. This report content is based on information collected and supplied to Nanoforum in good faith by external sources believed to be accurate. No responsibility is assumed by Nanoforum for errors, inaccuracies or omissions. Care has been taken to include references to the original source for all information included in the report. Please notify the editor in case any reference is missing. This Nanoforum report is downloadable from the network Website at www.nanoforum.org About Nanoforum Nanoforum is a thematic network funded by the European Commission, aiming to promote and raise the standard of nanotechnology activities throughout Europe. Nanoforum comprises a consortium of leading European nanotechnology organisations led by the Institute of Nanotechnology (UK) and including VDI Technologiezentrum (Germany), CEA-LETI (France), Malsch TechnoValuation (Netherlands), METU (Turkey), Unipress (Poland), Sofia University (Bulgaria), Spinverse (Finland), BIT (Austria) and NanoNed (The Netherlands). Nanoforum is an information source for the European Community that unites disciplines and countries. Nanoforum provides a resource for business, research, government and financial institutions across Europe.

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The present report is a publication of Nanoforum, published online at www.nanoforum.org Series: Nanoforum General Reports:

• 1st Nanoforum General Report: “Nanotechnology helps solve the world’s energy problems”, first edition published in July 2003, updated in December 2003 and April 2004.

• 2nd Nanoforum General Report: “Nanotechnology in the New EU Member States and Candidate Countries; Who’s who and research priorities”, first edition published in July 2003, updated in November 2003 and September 2005.

• 3rd Nanoforum General Report: “Nanotechnology and its implications for the health of the EU citizen”, first edition published in December 2003.

• 4th Nanoforum General Report: “Benefits, Risks, Ethical, Legal and Social Aspects of Nanotechnology”, first edition published in June 2004, updated in October 2005.

• 5th Nanoforum General Report: “Education Catalogue for Higher Education in Nanotechnology”, published in March 2005.

• 6th Nanoforum General Report: “European Nanotechnology Infrastructure and Networks”, published in July 2005.

• 7th Nanoforum General Report: “European Support for Nanotechnology Small and Medium Sized Enterprises”, published in December 2005.

• 8th Nanoforum General Report: “Nanometrology”, published in July 2006.

Other more specific Nanoforum publications: “Nanotechnology in the EU – Bioanalytic and Biodiagnostic

Techniques”, published in September 2004. Nanoforum and European Commission: “Outcome of the Open

Consultation on the European Strategy for Nanotechnology”, published in December 2005.

“Funding and Support for International Nanotechnology Collaborations”, published in December 2005, updated in July 2006.

“Nanotechnology in Agriculture and Food”, published in April 2006. “Risk governance in nanotechnology”, published in September 2006. “Nanotechnology in Consumer Products”, published in October 2006. “Nanotechnology and Construction”, published in November 2006. “Human enhancement from different perspectives”, published in

November 2006. “Intellectual property in the nanotechnology economy”, published in

January 2007. “Education in the Field of Nanoscience”, published in January 2007.

Series Socio-Economic reports:

• “VC Investment opportunities for small innovative companies.” April 2003

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• “Socio-economic report on Nanotechnology and Smart Materials for Medical Devices”, December 2003.

• “SME participation in EU research programmes”, October 2004. Series background studies to policy seminars:

• “Nanotechnology in the Nordic Region”, July 2003. • “Nano-Scotland from a European perspective”, November 2003. • Report from the ‘Nano and the environment’ workshop, Brussels, 30

and 31 March, 2006, published in May 2006.

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Chapter 1 Executive summary and introduction This 9th Nanoforum General report presents a concise introduction and contribution to the expert debate on trends in nanomaterials and nanotechnologies for applications in the civil aeronautics and space sectors in Europe. We explicitly exclude any military R&D and applications, as this falls outside the mandate of Nanoforum. Our target audiences are twofold: non-experts of an academic level with a general interest in the potential of nanotechnology for aerospace applications, and experts involved in setting the strategic R&D agenda in this field. This chapter should be helpful to decision makers in the EU, national governments, and public and private R&D labs aiming to set priorities in R&D or funding programmes. Chapter 2 reviews current trends in materials R&D on some selected materials for applications in aeronautics and space. This chapter is written from the perspective of materials scientists and includes information on trends in materials and production processes. The focus is on Carbon Nanotube reinforced polymers, metallic materials and polymer nanocomposites. Carbon Nanotube reinforced polymers are investigated for aerospace applications because of their good strength to weight ratio, flame and vibration resistance, antistatic and electrical properties. Much research is still needed before real applications in aerospace can be expected. Nanometals are investigated for their hardness and suitability in hard coatings. For cost-effective production, these materials must find application by 2009 in sectors other than those of high value, such as aerospace. The new nanometal production technology Severe Plastic Deformation (SPD) promises higher strength, corrosion and wear resistance and other benefits of nanometals compared to other metals. However, this production technology must be developed further before it can be applied in industrial production. Relevant projects are ongoing. There are three relevant types of polymer nanocomposites: layered silicate (clay); nanofibre / carbon nanotube filled polymer composites; and high performance polymer nanocomposite resins. Layered silicate polymer nanocomposites are investigated for a wide range of applications including flame retardant panels and high performance components in aerospace. Carbon nanotube filled polymer composites are still in the research phase but are seen as promising for aerospace applications. Aerospace applications of high performance polymer nanocomposite resins need the successful incorporation of the nanoparticles in thermoset resins. This chapter may be most interesting for materials scientists or those who intend to apply nanomaterials in aerospace applications. Chapter 3 presents a review of the state of the art of nanotechnology for aeronautics applications and analysis of future trends. We limit ourselves to civil aviation and airplanes. Aircraft companies are investigating new

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materials for application in airplanes to accommodate the expected growth in passenger numbers of 5% per year for the coming 20 years and taking into account more stringent legislation including environmental, health and safety regulations. These trends impose the objective of developing lighter materials with equal or improved robustness as current materials used in aerospace (corrosion resistance, damage tolerance, ability to be repaired). Leading companies including Boeing, Airbus and British Aerospace are collaborating with universities and research centres on projects to develop nanotechnology for aerospace. Nanotechnology is currently not incorporated in aircraft, but is expected to enter the market in the coming years. The stringent safety requirements, conservative attitude in the industry and need for industrial scale production processes contribute to a longer time to market than in other sectors. Nanomaterials and nanoelectronics can be applied in airframes and components, coatings, engines, sensors, electrical and electronic components and hardware and other applications. They are being investigated for uptake in aircraft on a large scale. Foreseen benefits include cost reduction, reduced environmental burden and enhanced passenger comfort. Uptake of nanomaterials and nanoelectronics in aircraft may be slower than in other sectors, but there is clear interest from the industry. This chapter may be most interesting to researchers and policy makers in nanotechnology and in aeronautics research. Chapter 4 presents a review of the state of the art of nanotechnology for spacecraft applications and analysis of future trends. The space sector deals with all technologies needed for travelling outside the earth atmosphere. This includes satellites, rockets, international space station and planetary missions, science payloads and futuristic visions such as the space elevator. Two developments in space are driving technology developments. National ambitions to explore outer space drive the quest for more autonomous systems as well as better life support for astronauts. Commercial activities making use of space require cost and weight reduction. Technologies are also being developed for existing issues such as radiation protection, extreme and varying temperatures and improved engines. Nanotechnology can be applied in new materials, electronics and energy supply for future spacecraft. Nanomaterials are being investigated for their thermal, electrical and optical characteristics as well as strength and cost effectiveness. Research focuses on nanoparticles and carbon nanotubes for mixing into polymers and composites, and smart materials. Spacecraft electronics can benefit from the fast innovation in the electronics industry sector. Onboard electronics must in addition be radiation resistant, thus incorporating carbon nanotubes which are relatively radiation resistant, in electronics may be especially attractive for space applications. Space research is more focused on applied electronics such as sensors. A bottleneck for the uptake of nanomaterials and nanoelectronics in spacecraft is the need to develop efficient characterisation and modelling tools for testing the materials and devices. Efficient energy generation and storage is very

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important for rockets as well as other spacecraft. Nanotechnologies can improve the existing energy generation and storage technologies, including propellants, solar cells, fuel cells and hydrogen storage, and batteries. Life support is becoming more important due to longer manned missions and space tourism. Keeping the air breathable, maintaining a clean water supply, controlling temperature, air humidity and the health of the astronauts can benefit from nanotechnologies applied in gas storage, waste water treatment and sensors. These technologies are mainly developed for the electronics and medical sectors and adapted for application in space. Satellites can be used for scientific observation of the earth or universe and for communication. The main trend in research is the quest to build more integrated and smaller nano/pico satellites. Relevant nanotechnologies include carbon nanotube based sensors, nanosensors, nanoparticles for imaging instruments and quantum information. Futuristic visions include the space elevator based on a long cable spun from carbon nanotubes and space colonisation. Autonomous systems such as satellite swarms and nanorobotics may one day be used in exploring other planets. Nanotechnologies are attractive for the space sector as they enable a reduction in costs, novel space missions, testing of new technologies in space and futuristic visions. Applications are foreseen in 0-5, 5-10 and 10-15 years in space devices, subsystems and systems. This chapter may be most interesting for researchers and policy makers in nanotechnology and in the space sector. Chapter 5 summarises expressed needs for future R&D for nanomaterials and nanotechnologies for aeronautics and spacecraft. The focus is on gaps in current research and needs for technical performance of available materials and devices which are critical enablers of future aeronautic and space systems. On a general level, there is a need to educate sufficient numbers of qualified scientists and engineers to work in R&D for the aerospace sector in Europe. Another general issue is the lack of cooperation between companies and research organisations in aerospace and in nanotechnology. SMEs in the supply chain will have to implement performance enhancing practices. To identify technical needs for future aeronautics, the goals set by the advisory council for aeronautic research in Europe in their Strategic Research Agenda are taken as reference. These technical requirements address quality and affordability, environment, security, safety and air transport efficiency. Relevant on-board nanotechnologies can be applied in airframes; propulsion; aircraft avionics, systems and equipment. Nanotechnology may be applied in aircraft some twenty years after the technologies have been validated for airworthiness. New research needs for nanotechnology applications in space include nanomaterials for spacecraft structure and energy production and storage including solar cells, fuel cells, batteries and accumulators and capacitors. Other nanotechnology research needs are in data storage, processing and transmission; life support systems; and nanomaterials and thin films for

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spacecraft. Visionary applications of nanotechnology in space include molecular nanotechnology and electronics for space, the space elevator, nano and pico satellites, the gossamer spacecraft and space solar power. Choices of priorities in nanotechnology R&D for space must be based on the technological readiness and applicability. The R&D is expected to take a decade before being implemented in spacecraft. This chapter may be most interesting for decision makers on future research priorities in nanotechnology and in aerospace. Chapter 6 consists of an economic analysis of the European aerospace sectors. The European Commission’s Aerospace policy (STAR21, 2002) aims for a strong competitive position of Europe’s aerospace industry and for combined public and private funding for civil aeronautics of €100 billion by 2020. The major manufacturers for aviation are Airbus in Europe and Boeing in the US, with other important global players in Russia, Brazil, Canada and Ukraine. The global market for airline passenger traffic is expected to increase 5.3% per year until 2023. Airbus expects a need for 16,601 new passenger aircraft, in smaller aircraft in the EU market and larger ones in Asia Pacific. The expected market size is €1.48 trillion. Europe’s market size is expected to remain constant, the US will decline and Asia will increase its market share. The European Technology Platform ACARE states that the investment in R&D by the private sector in Europe is comparable to the US, while the European public funding is only 25% of US public funding. Keeping sufficient qualified human capital and industrial companies in Europe requires a coordinated effort by the EU and member states. They have developed a strategic research agenda to accomplish this. Space exploration and exploitation are seen as major goals for many countries. Budgets amount to billions of euros per year. The European Space Agency intends to use new systems, new architectures and to explore technologies to reinvent the design of space missions. The US aims for space exploration are in manned missions to the moon and Mars, and homeland security and defence. Russia still launches the most spacecraft, and intends to develop a new, reusable spacecraft and collaborate with the EU on satellite navigation and science and technology. China has put a person in space, and wants to send missions to the moon. It is negotiating with Russia and the EU about space collaborations. Japan and India also have space policies. Research in nanotechnology for aerospace applications has already led to 62 patented inventions in materials, surface treatment and coatings, engine components, batteries, propellants, and electronics. Of these patents, 23 are registered in the USA and 17 in European countries. SMEs provide services and additional expertise in R&D to major corporations. Several EU funded projects support SME’s in the aerospace sector. This chapter may be most interesting for industrialists and economic and innovation policymakers.

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Chapter 7 analyses the environment, health and safety aspects of nanotechnology for aerospace. The debate on these aspects of engineered nanomaterials specific for applications in the aerospace sector is only just emerging. General toxicology of engineered nanomaterials and occupational nanosafety issues are also applicable to the aerospace sector. These “nanorisk” research projects which are starting now must be complemented with specific life-cycle analyses and exposure scenarios for applications in aircraft and spacecraft. Potential benefits of nanotechnology in aerospace for the environment, health and safety are also being discussed. To enhance the likelihood of positive impacts, better implementation strategies must be developed. This chapter may be most interesting for risk assessment specialists and policymakers on nanoregulation. Chapter 8 analyses the ethical, legal and social aspects of nanotechnology for civilian aerospace. On the one hand, the current international treaties and national legislation governing the aeronautics and space sector impose boundaries on the nanoscience and nanotechnology research which can be done for aerospace applications. On the other hand, developments in aerospace and in nanoscience and nanotechnology enable new activities and systems which were not possible before. Small satellites in earth orbit can be applied in telecommunication and earth observation for peaceful as well as security applications. In the very long term, space exploration may also be enabled by miniaturisation and nanotechnology. The ethical, legal and social implications of unmanned air and spacecraft need to be discussed. However, the review of these issues in the framework of this report is very partial. Further research is needed which is not restricted to civilian applications, and also investigates the legislative framework for aeronautics. Education and outreach must include information and debate about ethical, legal and social aspects of nanotechnology in aerospace. This chapter may be most interesting for nanoscience & society experts and policymakers in nanoregulation and public dialogue.

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Table 1.1 summarising trends in the whole report. Level of integration 0-5 years 5-10 years >10 years Societal boundary conditions for nanotechnology in aerospace

Current treaties and regulations guide nanotechnology R&D (ch8)

More stringent regulations incl. EHS regulations require (nano) innovations in aeronautics (ch3)

Global & national aims: space exploration & exploitation (ch6)

Nanotoxicology and occupational nanosafety research ongoing (ch7)

Aircraft passenger numbers will increase by 5%/year until 2023 (ch3,6)

Impact of nanotechnology in aerospace on society

Need to start life cycle analysis & exposure scenarios for aerospace applications of nanomaterials (ch7)

Need action to stimulate EHS benefits of nanotechnology for aerospace (ch7)

Nanotechnology applications in aerospace will enable new activities and require changes in legislation (ch8)

Nanotechnology applications in aerospace will enable new activities and require changes in legislation (ch8)

Economic factors affecting nanotechnology uptake in aerospace

Space budgets amount to billions of euros per year (ch6)

European public and private aeronautic R&D funding €100 billion by 2020 (ch6, EU STAR21)

EU stimulates SMEs in space sector (ch6)

2023: 16,601 new aircraft needed, market size €1.48 trillion (ch6, Airbus)

Technical system Nano/picosatellites (ch4)

Russia: new reusable spacecraft (ch6)

ESA: new systems, architectures & technologies to reinvent design of space missions (ch6)

Satellite on chip, autonomous satellites swarm (ch4)

Aircraft weight half of current conventional (ch3, NASA 2001)

Space elevator, colonisation, autonomous nanorobot swarm (ch4)

Technical subsystem Black box using nanosensors, CNT based electronic noses; CNT based lab on a

2015: fuel cells for onboard aircraft systems (ch3, Boeing, ch4)

Quantum devices for information management (ch4)

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chip/biochip (ch4) Battery using

nanoelements, quantum dot solar cells, drug delivery, CNT based imaging instruments (ch4)

Material / component

2009: apply metallic materials in mass markets (ch2, Lux 2006)

Industrial scale Severe Plastic Deformation process for metallic nanomaterials? (ch2)

2020: over 163 million kg nanomaterials in composites, value $2 billion (ch2, Freedonia, 2006)

2006: 62 patented inventions of nanotech for aerospace (ch6)

Need for lighter, stronger materials for aeronautics (ch3)

2020: 40% of nanoclay/CNT polymer composites will be applied in aerospace (ch2, Freedonia, 2006)

Clay-polymer nanocomposites for flame retardant panels and high performance components in aerospace (ch2)

CNT filled polymer composites (ch2,4) CNT reinforcing coatings, CNT in transistors, CNT based memory, MRAM (ch4)

Smart materials, bio memory (ch4)

Nanoparticles reinforcing polymers and composites, nanoparticles in propellants (ch 4)

High performance polymer nanocomposite resins (ch2)

Smart textiles (ch4)

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Table of contents:

Nanotechnology in Aerospace............................................................. 2 Chapter 1 Executive summary and introduction .................................... 6 Chapter 2 – Nanomaterials in Aerospace............................................ 16

2.1 Introduction........................................................................... 16 2.2 Advancement of Nanotube-Reinforced Composites...................... 16 2.3. Nanostructured metals ........................................................... 17 2.4 The advancement of severe plastic deformation ......................... 18 2.5 The projects related to aircraft company business ...................... 19 2.6 Publications and Conferences ................................................... 20 2.7 Polymer Nanocomposites......................................................... 20

2.7.1 Introduction ..................................................................... 21 2.7.2 Definitions ....................................................................... 21 2.7.3 Classification .................................................................... 22 2.7.3.1 Layered silicate (clay) nanocomposites ............................. 22 2.7.3.2 Nanofibres/carbon nanotube in polymer nanocomposites .... 23 2.7.3.3 high-performance PNCs resins ......................................... 26

Chapter 3: Review of state of the art of technology and future trends in Aeronautics.................................................................................... 28

3.1. Airframe and components....................................................... 30 3.2. Coatings............................................................................... 34 3.3. Engines ................................................................................ 36 3.4. Sensors................................................................................ 37 3.5. Electrical/electronic components and hardware ......................... 38 3.6. Others ................................................................................. 39 3.7. Conclusion............................................................................ 39

Chapter 4 Review of state of the art of technology and future trends in Spacecraft ..................................................................................... 40

4.1 Introduction........................................................................... 40 4.2 Materials ............................................................................... 42

4.2.1. Nanoelements ................................................................. 43 4.2.1.1. Materials using nanoelements......................................... 45 4.2.2 Materials conclusion .......................................................... 49

4.3. Electronics............................................................................ 49 4.3.1 Carbon nanotubes for transistors ...................................... 50 4.3.2 Memories / Data storage................................................. 51 4.3.4 Electronics conclusion........................................................ 53

4.4. Energy generation and storage................................................ 54 4.4.1. Propellants...................................................................... 54 4.4.2. Solar cells ....................................................................... 55 4.4.3. Fuel cells ........................................................................ 56 4.4.4. Batteries......................................................................... 58 4.4.5 Energy conclusion ............................................................. 58

4.5. Life support .......................................................................... 59 4.5.1. Global life support............................................................ 59

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4.5.2. Medical systems .............................................................. 60 4.5.3. Textile ............................................................................ 63 4.5.4 Life support conclusion ...................................................... 63

4.6. Satellites / Science payloads................................................... 64 4.6.1. Satellite subsystems......................................................... 67 4.6.2. Science payloads ............................................................. 68 4.6.3 Satellites / Payloads conclusion: ......................................... 72

4.7. Futuristic visions ................................................................... 72 4.7.1. Space elevator................................................................. 73 4.7.2. Space colonisation ........................................................... 74 4.7.3. Autonomous systems ....................................................... 75 4.7.4 Futuristic visions conclusion ............................................... 77

4.8 Conclusion............................................................................. 77 Chapter 5: Summary of Needs in Aerospace Research......................... 80

5.1 Aeronautics ........................................................................... 80 5.1.2 Airframes......................................................................... 81 5.1.3 Propulsion........................................................................ 81 5.1.4 Aircraft avionics, systems and equipment............................. 82 5.1.5 Environment..................................................................... 83 5.1.6 Safety and Security........................................................... 84 5.1.7 Quality and affordability..................................................... 85 5.1.8 European Air Transport System .......................................... 86 5.1.9 Future concepts for Guidance & Control ............................... 86 5.1.10 Current Research ............................................................ 86 5.1.11 Aeronautics application in other industries.......................... 88 5.1.12 Funding and investment................................................... 89 5.1.13 Policy............................................................................. 89 5.1.14 Education and Training .................................................... 89 5.1.15 SME .............................................................................. 90 5.1.16 Conclusion ..................................................................... 90

5.2 Statement of needs for Research and Development in Space ....... 90 5.2.1 Introduction ..................................................................... 90 5.2.2 Nanomaterials for space craft structure ............................... 92 5.2.3 Energy Production and Storage........................................... 94 5.2.4 Data Storage, Processing and Transmission.......................... 95 5.2.5 Sensors ........................................................................... 98 5.2.6 Life support systems ......................................................... 99 5.2.7 Nanomaterials and thin films for spacecraft ........................ 100 5.2.8 Visionary Applications...................................................... 101 5.2.9 Conclusion ..................................................................... 103

Chapter 6: Economic Aspects ......................................................... 105 6.1 Introduction......................................................................... 105 6.2 Aviation............................................................................... 105

6.2.1 Global markets in the aviation industry.............................. 107 6.3 Space ................................................................................. 111 6.4 How can Nanotechnology Impact on these Strategies? .............. 114

6.4.1 Patenting of Nanotechnology Advances that have Applications in the Aerospace Industry ............................................................ 114

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6.5 Role of SMEs........................................................................ 118 6.6 Conclusions ......................................................................... 118

Chapter 7: Environment, Health and Safety Aspects.......................... 120 7.1 Introduction......................................................................... 120 7.2 EHS risks............................................................................. 121

7.2.1 Health risks.................................................................... 123 7.2.2 Safety risks .................................................................... 123

7.3 Environmental benefits.......................................................... 123 7.4 Health benefits..................................................................... 125 7.5 Safety benefits..................................................................... 125 7.6 EHS Regulation .................................................................... 125 7.7 Conclusion........................................................................... 127

Chapter 8: Ethical, Legal and Social Aspects .................................... 129 8.1 Introduction......................................................................... 129 8.2 Regulations.......................................................................... 130 8.3 Ethical, Legal and Social Aspects ............................................ 133 8.4 Conclusion........................................................................... 135

References................................................................................... 137

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Chapter 2 – Nanomaterials in Aerospace

2.1 Introduction

This chapter identifies some of the technical challenges and the key research efforts in the field of nanomaterials for aerospace applications. Specifically, it focuses on carbon nanotube-reinforced polymers and materials produced by severe plastic deformation (SPD). Selected European projects and world conferences related to aerospace are included. The state of the art of polymer nanocomposite research is also reviewed.

In the aerospace industry, there is a great need for new materials which exhibit improved mechanical properties. Materials possessing high strength at a reduced mass and size make lighter aircraft with lower fuel consumption. The development of new materials with tailored properties is a primary goal of today’s materials science and engineering.

However, the possibility of obtaining improved mechanical properties by the conventional methods of cold working, solution hardening, precipitation hardening, etc., has been almost exhausted. The current trend is to integrate intelligence and multifunctionality into the varied components of aerospace systems and vehicles.

The 6th EU Framework Project ‘NanoRoadSME (Nanomaterial Roadmap 2015)’ has published a report entitled “Overview on Promising Nanomaterials for Industrial Application”. This report identifies the following trends in materials for automotive and aerospace applications: lighter and stronger materials, transparent windshield, lacquer safety and polymer matrix composites. Also included in the report are the projected cost and market evolution of each material’s technology, the timelines for possible industrial applications, and a list of companies and institutes actively involved in aerospace nanomaterial R&D.

2.2 Advancement of Nanotube-Reinforced Composites

The extraordinary stiffness, higher than that of diamond (ten times higher than that of any other available material), high toughness, changeable conductivity and the specific tensile strength of carbon nanotubes (CNTs) makes them eminently suited as reinforcing elements in macroscopic composites.

With a potential high strength-to-weight ratio and multifunctionality, carbon nanotube reinforced polymer composites may provide a unique

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option for the aviation industry. Their use can enhance a material’s ability to resist vibration and fire (Nano letters, 2006, Nature Materials, 2005).

Minute amounts give polymers antistatic properties, while concentrations as low as 1% total weight trigger electrical conductivity. The intimate relationship between the electrical and mechanical properties of these composites enables them to exhibit smart capabilities (Chipara, 2005).

A recent review article identified four critical requirements for effective fibre reinforcement of composite materials: a large aspect ratio, transfer of interfacial stress, a good dispersion, and alignment (Advanced Materials, 2006). While carbon nanotubes typically have very high aspect ratios, their absolute lengths are still low, which makes them difficult to manipulate and process. Moreover, the high cost and relatively short lengths of CNTs combined with an inability to effectively disperse and align them within a host matrix, currently preclude the development of composite structures that could supplement or replace conventional aerospace components.

However, there are a number of research efforts underway that address these and other concerns. Investigators worldwide are in pursuit of advanced synthesis processes to facilitate large-scale production of CNTs of macroscopic lengths, while others are focusing on combining shorter CNTs into longer and more useable composite fibres.

Functionalisation and irradiation of polymer-embedded nanotubes and nanotube fibres also have been shown to enhance dispersion and strengthen nanotube-matrix interactions, allowing for further improvement of the mechanical properties of CNT-reinforced composites.

Despite these efforts, much additional R&D is still needed to realize the full potential and implementation of these advanced composites (Taczak, 2006).

2.3. Nanostructured metals

Nanostructured metals have nanosized grains, which gives them greater strength and hardness. Heralded as alternatives to toxic materials like chromium for coatings and for structural applications, their use can be hampered by their increased brittleness and complex processing requirements.

Nanostructured metals can provide very hard coatings that are resistant to corrosion, useful for applications including aerospace components, such as landing gear and construction equipment such as drill bits and bulldozer blades.

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Low volume, high margin applications for the aerospace and defence industries, and high-end sporting goods are largely driving the development of nanostructured materials. However, for real success there is a need to start establishing customers in other areas by 2009 (Lux, 2006).

2.4 The advancement of severe plastic deformation

The possibility of improving the properties of metallic materials by the conventional methods of cold working, solution hardening, precipitation hardening, etc., has been almost exhausted. According to the well known Hall-Petch relationship, the yield strength is a linear function of the inverse of the square root of grain diameter (d-1/2) which implies a 10 times higher grain boundary strengthening when the grain size is reduced by 2 orders of magnitude. One can expect that intensive grain refinement down to the nanometre scale will lead to a rapid increase in strength. Grain refinement down to the nanometre scale thus offers good prospects for a new generation of high strength materials.

To produce such high strength, nanocrystalline materials, the development of new processing methods is necessary. Nanomaterials can be produced following bottom-up methods (such as inert gas condensation, consolidation of nanopowders, electro deposition or crystallization from an amorphous state), but it is only possible to produce small items of such materials, usually with a diameter and length no greater than a few millimetres. Therefore, it is probable that only a top-down approach can offer good “technological” prospects. Such a concept consists in the transformation of metals or alloys possessing a conventional grain size into bulk materials with a submicron- or nanoscale structure by the application of severe plastic deformation (SPD). The advantages of the SPD methods are: (i) a 100% dense nanostructured material is obtained, (ii) conventional materials are used as precursors, (iii) there are no toxicological issues involving the use of nanopowders. Thus, research in this field has attracted the attention of numerous scientific groups throughout the world including representative European institutions.

With the growing experimental evidence, it can be concluded that for some cases SPD in processed materials may exhibit very high strength combined with acceptable ductility. In some cases superplastic behaviour was observed. Other papers reported increased high cycle fatigue life, enhanced charging capacity and diffusion rate of hydrogen, improved corrosion and wear resistance. Such excellent properties cannot be achieved using conventional fabrication techniques. SPD processed nanometals are thus prospective materials for many structural and functional applications in the aerospace industry.

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There is clearly a great potential for bulk nanostructured materials, particularly in the aerospace industry. However, there are some limitations to their wider use which result from the current restrictions on the cost and size of SPD processed elements. One of the routes to ease these restrictions is offered by a modification of existing SPD techniques. Another route aims at the development of new methods. Finally, it must be stated that to introduce products having a nanometal structure into the market, will need a major research and development effort in order to fully explore and understand the specific properties of SPD materials and to optimize the processing route for particular applications.

2.5 The projects related to aircraft company business

Airbus Industries and the MITRE Corporation’s Centre for Advanced Aviation System Development (CAASD) (O’Donnell) are focused on obtaining the highest performance, a ‘maintenance-free’ airframe and environmental friendliness. However, although nanotechnologies promise significant benefits for aerospace applications, mature and robust solutions are mandatory.

For this purpose, in order to meet future challenges and to incorporate worldwide best state-of the-art technological solutions, cooperation with external suppliers and strategic partners is essential.

For example, the Airbus Industry in Stade is interested in manufacturing some composite parts (vertical stabilisers, pressure bulk heads, etc.) for all types of aircraft.

The Value Improvement through a Virtual Aeronautical Collaborative Enterprise (VIVACE) consortium is a €70 Million European Project which is led by Airbus, and includes 50 partners, all of which are well recognised names in the aerospace and IT industries. The global aims of VIVACE are to reduce the time to market, an increased integration of the supply chain and substantial reduction of the operating costs.

The project entitled: “Nano-Structured and Reinforced Composite Materials” is being undertaken at Imperial College London (2006). This project pursues a range of approaches to nano-reinforcement of polymer composites, including CNT-reinforced polymer fibres, CNT-grafted carbon fibres, and CNT reinforced thermoset resins. The research also includes micromechanical modelling of CNT reinforced composites and feasibility studies into future exploitation routes. The project is collaboration between three departments within the College – Aeronautics, Chemistry, and Chemical Engineering. QinetiQ of Farnbourough in Hampshire, UK also collaborates in the project.

The project entitled: “Self-Healing Intermetallics (Metal, Polymer) Matrix Composites” is taking place at universities in the Netherlands to develop

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new concepts in design and to apply self-healing mechanisms in the context of intermetallic alloys and intermetallic-based composite materials.

Owing to increased efforts in the areas of materials and process development, design, manufacturing (scale-up), and certification of MMCs (Metal-matrix composites) a number of key applications are now a well established reality for aeronautical applications. A very obvious motivation in introducing MMCs into aeronautical systems is the optimal balance of specific strength and stiffness compared with other competing structural materials.

The possibility of integrating intermetallic phases, which exhibit self-healing properties, e.g., yield stress anomaly (YSA) or the formation of an oxygen diffusion barrier (OBD) into a (metal, polymer) matrix remains almost uncharted territory. However, it certainly constitutes a very fine engineering modelling system of potentially great relevance for aeronautical applications.

The INTAS project “Nanocomposite sliding bearings for air bleed valves” (NANOBLEBUS, 2005-2007) aims to develop new nanocomposite materials for the production of sliding bearing sleeves used in the (A380) AIRBUS aircraft air conditioning system.

2.6 Publications and Conferences

CNT-NET and NANOCOMP are two networks funded by the European Union that address the subject of nanotube and nanofibre polymer composites from different perspectives, though both aim to stimulate the understanding and application of such systems (Shaffer & Kinloch, 2004).

Cientifica, an international nanotechnology consulting firm, recently published a report entitled, “Nanotubes for the Composites Market.” This report addresses carbon nanotube applications for composites, if and when nanotubes will replace carbon fibre, and why carbon nanotubes still remain prohibitively expensive. Also included are a market analysis, a prospectus covering the years 2005 to 2010 and an extensive worldwide list of nanotube suppliers.

In 2003, the 1st annual Nano Materials for Aerospace Symposium was held in Corpus Christi, Texas. This conference series has since been renamed Nanomaterials for Defence Applications and the latest meeting was in Virginia Beach, Virginia, in May 2006. The next meeting will occur in May 2007 in San Diego, CA.

2.7 Polymer Nanocomposites

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2.7.1 Introduction The reinforcement of polymers (thermoplastics, thermosets, elastomers) using fillers, whether inorganic or organic, is common in the production of modern plastics. Polymer composites are strong, yet remarkably lightweight and so they are leading the field in aerospace applications. This is all down to the fact that researchers are always looking for ways to reduce the amount of fuel needed for flights and a key way of achieving that is by reducing the weight of the aircraft itself. Similarly, the amount of energy needed to propel an object into space means that spacecraft must be even stronger and lighter, plus the harsh and varied conditions they face will put even the best materials to the test. By 2020, more than 163 million kg of nanomaterials, valued at $2 billion, will be used to produce nanocomposites, with demands for nanotubes alone exceeding $1 billion (Freedonia Group, 2006). Advances will be fuelled by declining prices of nanomaterials and composites, as production levels increase and technical issues concerning dispersion of nano-additives in compounds are overcome. Over the near term, growth will be the fastest in higher-priced resins such as engineered plastics and thermoplastic elastomers as much of the initial demand will be in higher-end applications. Eventually, however, nanocomposites based on commodity plastics, such as polypropylene, polyethylene and PVC, will dominate the market. While nearly all of the current demand is in thermoplastic resins, nanocomposites based on thermosets will grow to over 20% of the market by 2020. Unsaturated polyester will become the primary thermoset used in nanocomposites, as nanomaterial additives will increasingly enhance or replace glass fibre-reinforced materials in a number of applications. Apart from packaging and motor vehicles, aircraft is a key market for nanoclay- and nanotube-polymer composites. It will remain important through the end of the next decade, accounting for nearly 40% of demand in 2020. Polymer nanocomposites are expected to penetrate a number of applications, driven by their improved barrier, strength and conductive properties, as well as reduced weight, possibility to increase production speed of parts and to replace higher-priced materials. 22-23rd of February, 2007 in San Antonio, Texas, USA, an international conference “The Future of Nanoplastics” has been organised. Up-to-date information on polymer materials (among them nanocomposites) for aerospace applications is currently provided by RAPRA.

2.7.2 Definitions Polymer nanocomposites - PNCs (or polymer nanostructured materials) represent an alternative to conventional-filled polymers or polymer blends. In contrast to the conventional systems, where the reinforcement is on the order of microns, PNCs take advantage from unique effects of the addition of nanometre-sized inorganic materials to a polymer matrix.

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These effects however, are driven not only by the small size but unusual shapes and aspect ratios (L/h > 300) of the additives and include extraordinarily high interfacial areas or highly aligned phases of the additive. Due to their efficiency, nanofillers can be used in small quantities (less than 5% by weight). The constituent inorganic additives can be applied in a form of particles, tubes and wires, two-dimensional platelets and porous materials. Their application brings improvements in mechanical strength and aging resistance, reduction of wear and flammability, barrier to diffusion, optical transparency, and unprecedented morphologies such as interpenetrating networks. However, from both a commercial and military perspective, the value of PNCs technology is not based solely on mechanical enhancements of the neat resin. Rather, it comes from providing value-added properties not present in the neat resin, without sacrificing the inherent processability and mechanical properties of the resin. Traditionally, blend or composite attempts at multifunctional materials require a trade-off between desired performance, mechanical properties, cost, and processability. Researchers developed two main PNCs fabrication methodologies: in-situ routes and exfoliation. Currently, researchers in industry, government, and academia worldwide are heavily investigating exfoliation of layered silicates, carbon nanofibres/nanotube-polymer nanocomposites, and high-performance PNCs resins (AFRL Horizons).

2.7.3 Classification In general, polymer nanocomposites fall into three categories, depending on the form of nanoparticles being used: layered silicate or nanofibres / carbon nanotube-polymer nanocomposites and high-performance PNCs resins.

2.7.3.1 Layered silicate (clay) nanocomposites These minerals considerably increase the mechanical and thermal properties of standard polymers, offering improvements over conventional composites in mechanical, tribological, thermal, electrical and barrier properties. Furthermore, they can significantly reduce flammability and maintain the transparency of a polymer matrix. Loading levels of 2-5% by weight result in mechanical properties similar to those found in conventional composites with 30-40% of reinforcing material. The attractive characteristics of layered silicate nanocomposites already suggest a variety of possible industrial applications for layered silicate (clay) nanocomposites, including flame retardant panels and high performance components for aerospace. The special properties of clay-polymer nanocomposites expand the use of resins and blends based on polyolefins, styrenics, polyamides or

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polyesters. Other PNCs are also based on thermosets, including epoxies, unsaturated polyesters and polyurethanes.

Fig. 2.1 Layered silicate nanocomposite (IMI, AFRL)

2.7.3.2 Nanofibres/carbon nanotube in polymer nanocomposites A literature search provides many examples of PNCs, demonstrating substantial improvements in mechanical and physical properties. However, the nanocomposite properties discussed are generally compared to unfilled and conventional-filled polymers, but are not compared to continuous fibre reinforced composites. Although PNCs may provide enhanced, multifunctional matrix resins, they should not be considered a potential one-for-one replacement for current state-of-the-art carbon-fibre reinforced composites. The key to any of fabrication processes is the engineering of the polymer-nanoparticle interface where researchers commonly use surfactants. These range from small molecules ionically associated with the nanoparticle surface for layered silicates to chemically bound small molecules or physi-absorbed polymers for nanotubes. These surface modifiers mediate interlayer interactions by effectively lowering the interfacial free energy. Furthermore, they may serve to catalyze interfacial interactions, initiate polymerizations, or serve as anchoring points for the matrix and thereby improve the strength of the interface between the polymer and inorganic. However, the choice of the optimal modifier is at best empirical to date. The following points are evident about nanotube / polymer composites (Moniruzzaman & Winey, 2006): The properties of nanotube / polymer composites depend on a multitude of factors that include the type (SWNT, DWNT, MWNT), chirality, purity, defect density, and dimensions (length and diameter) of the nanotubes, nanotube loading, dispersion state and alignment of nanotubes in the polymer matrix, and the interfacial adhesion between the nanotube and

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the polymer matrix. These factors should be taken into account when reporting, interpreting, and comparing results from nanotube / polymer composites. Functionalisation of nanotubes provides a convenient route to improve dispersion and modify interfacial properties that may in turn improve the properties of nanocomposites, especially mechanical properties. The significant progress in nanotube functionalisation chemistry in recent years ensures that this approach will become more prevalent. Quantifying nanotube dispersion in polymers (and solvents) is an inherently challenging problem because it involves a range of length scales, and thereby multiple experimental methods are required. Fortunately, new experimental methods are applied to the problem, such as a fluorescence method to non-destructively detect isolated SWNT in a polymer matrix. Nanotubes have clearly demonstrated their capability as conductive fillers in polymer nanocomposites. Further advances with respect to electrical conductivity in nanotube / polymer composites are likely if only (or predominantly) metallic nanotubes could be used in the nanocomposites. Two approaches are actively being pursued in SWNT materials: modify the synthetic route to preferentially produce metallic nanotubes and sort the existing nanotubes. The physical properties of nanotube /polymer composites can be interpreted in terms of nanotube networks, which are readily detected by electrical and rheological property measurements. The nanotube network provides electrical conduction pathways above the percolation threshold, where the percolation threshold depends on both concentration and nanotube alignment. The nanotube network also significantly increases the viscosity of the polymer and slows thermal degradation. In contrast, it remains a challenge to reduce the interfacial thermal resistance of these nanotube networks, so as to take advantage of the high thermal conductivity of individual nanotubes in a polymer composite system.

The shielding effectiveness and electrical conductivity of carbon fibre-reinforced epoxy composites were investigated both theoretically and experimentally. The effects of fibre orientation and total composite thickness on shielding effectiveness were examined by electrical measurements and theoretical modelling and the dominant mechanism of electromagnetic interference shielding identified as absorption (Abdalla et al, 2006). Unidirectional carbon fibre reinforced epoxy straps were also proposed as fatigue crack growth retarders for aircraft construction (Colavita et al, 2006). Nickel nanostrands were mixed or infused into Hysol 9396 aerospace epoxy resin and the mechanical and electrical properties of the nickel-containing epoxy resin investigated. The influence of nickel nanostrand loading level, mode of their incorporation into the epoxy resin and magnetic orientation on mechanical and electrical properties of the composite were examined (Burghardt et al, 2006). New panel material for use in bulkhead and structural flooring in aircraft, using glass reinforced polymer faced sheets with a foam core and a Kevlar

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ballistic resistant backing has been described. Panels infiltrated with a fire retardant resin, were evaluated for their fire resistance, toxicity in fires, mechanical strength and ballistic resistance according to National Institute of Justice and ASTM standards (Cohen et al, 2005). In orbit, satellites are exposed to significant thermal variations. To ensure reliable operation of their on-board systems and equipment, a thermal control of the spacecraft is necessary using cold, neutral or warm coatings. The Materials and Coatings Laboratory of the Thermal Control Services at CNES (Toulouse, France) has elaborated a cold coating version by using a polysiloxane deposit on a metal substrate (such as polished aluminium or vacuum deposited silver). In geostationary orbit, polysiloxane, which has a high electrical resistivity, can accumulate implanted charges that can give rise to electrostatic discharges and damage the neighbouring electronic systems. To prevent any electrostatic discharge problems in geostationary orbit, the resistivity of coatings should be reduced without altering their thermo-optical properties, in particular the low solar absorptivity and the high emissivity for cold coatings. Several methods have been studied, such as the incorporation of carbon nanotubes (CNT) and indium tin oxide (ITO) nanoparticles in the polysiloxane matrix, with the objective of attaining a high transparency, a high emissive, and an antistatic resin (Hidden et al, 2006). The effects of processing parameters (compression moulding) on the mechanical properties of carbon/polyetherketoneketone (PEKK) thermoplastic composite laminates have also been studied. SEM was used to observe the different microstructures arising from various processing conditions. Optimum properties for the laminates have been established. The range of parameters can serve as a guide to consolidate carbon/PEKK laminates for high performance aerospace applications (Salek et al, 2005). Conductive multifunctional polymer nanocomposite “NanoSphalt” is a carbon nanofibre and fibreglass composite material (www.ohionanosummit.net). The nanofibres bring an entirely new property to fibreglass and other polymer composites – the ability to conduct electricity – which opens the door for new applications for lightweight but strong materials that are inherently not conductive (a deflective “skin” could be applied to aircraft to prevent damage from a lightning strike). The material was demonstrated at the Society for the Advancement of Material and Process Engineering’s annual conference in May, 2004, when researches lit a 75-watt bulb by running current through the model bridge. Other potential applications are: electrically conductive adhesives, energy harvesting, structural components with improved electrical / thermal conductivity (such as aircraft engines that can burn hotter and thus more efficiently). Fabrication, processing, chemical and physical treatment of various forms of carbon may have direct-end uses or may be further continued in order to produce polymer nanocomposites for: low-wear resistance aircraft brakes, protective coatings for satellites, superior insulating materials capable of heat-storage and transfer, novel batteries etc. Researchers working for aircraft industry try to find a way to replace copper wiring with

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polymer wiring made with electrically conductive carbon nanofibres. According to information from a wiring company, a Boeing 747 has approximately 225 km of wire weighing approximately 1600 kg. Theoretically, replacing that wire with conductive polymer will bring the wiring weight alone down to well below approximately 454 kg, which will positively impact the range and fuel efficiency of the aircraft. Scientists from University of Dayton Research Institute (OH, USA) and Air Force Research Laboratory (AFRL) have developed plastic that after being deformed, can spring back into shape when heated. Mixing carbon nanotubes with polymers creates “shape-memory” polymers that respond to heat, electricity and infrared light (published in the February 2004 issue of Nature Materials). It is believed that shape-memory polymers will be used in practical applications within 5 years, e.g. in large structures that need to be packed for launch and unfurled later.

2.7.3.3 high-performance PNCs resins Many potential aircraft applications depend on successful incorporation of the nanoelements in thermoset resins. NanoSperse in Akron (OH, USA) is now in full production of nanomaterial-reinforced polymers that are lighter, stronger and more durable than other composite polymers – as well as being thermally and electrically conductive. Henkel KGaA of Germany has commercialised a range of low-viscosity, one-part benzoxazine resins for use in the manufacture of large fibre-reinforced plastic parts for aerospace applications. The resins are stable at ambient temperature, have a long pot-life, and are easy to process (High Performance Plastics, June 2006, 4). In the same place, BASF AG of Germany reported a variant of its "Basotect" heat-insulating and sound-absorbing melamine resin foam - "Basotect TG" - which is 30% lighter than standard Basotect, making it particularly suitable for the construction of parts for aircraft interiors (High Performance Plastics, June 2006, 3). It can be additionally shaped by heat (High Performance Plastics, May 2006, 1). 3M AF3070 FST" is a new halogen-free, low-density adhesive film from 3M, intended to assist aircraft interior manufacturers in cutting their production times, and also in meeting increasingly strict fire, smoke, and toxicity regulations (EUREKA, 2006). New silicone film adhesive, which combines low outgases properties required for space applications with consistent bond thickness, has been reported (Riegler et al, 2006). The new film adhesive is comparable to a low outgas liquid adhesive and is considered suitable for various applications common to satellite manufacturing. The feasibility of developing a sprayable Chromium-Free Permanent Primer (CFPP) coating system, which consists of a commercial chromium-free, functional conversion coat, an abrasion-resistant PU elastomer permanent primer layer containing a chromium-free corrosion inhibitor,

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which forms chemical bonds with the conversion coat and a conventional aircraft topcoat, has been demonstrated. This CFPP coating system exhibits higher abrasion resistance against plastic media blasting than the topcoat. It permits selective stripping of the topcoat without removal of the primer or conversion coating. The topcoat may be selectively stripped off when required and a fresh topcoat reapplied, making the aircraft ready to fly again (Kovar et al, 2006). Attempts were made to modify polybenzimidazole (PBI) by high-energy radiation and low-pressure plasma treatment to permit the preparation of composites with the same polymer. The PBI composites were prepared by using an ultra-high-temperature-resistant epoxy adhesive to join the two polymer sheets. The adhesive had a service temperature range of -260 to +370 ºC and was highly resistant to acids, alkalis, solvents, corrosives, radiation, and fire. Before preparing the composite, the surface of the PBI was ultrasonically cleaned in acetone and modified by high-energy radiation for 6 hrs in the pool of a nuclear reactor that produced a mixed field of thermal and epithermal neutrons, energetic electrons, and protons, and gamma-rays at a dose rate of 37 kGy/h. Alternatively, the polymer was subjected to low-pressure plasma treatment with a 13.56-MHz radio-frequency glow discharge for 120 s at 100 W power with nitrogen as the process gas. A considerable increase in the joint strength was observed when the polymer surface was modified by either process. A further significant increase in joint strength occurred when the polymer surface was initially modified by exposure to low-pressure plasma followed by exposure to high-energy radiation. To simulate conditions in space, the joints were exposed to cryogenic (-196 °C) and high temperatures (+300 °C) for 100 hrs. Joints exposed to these conditions retained about 95 % of their strength. Microscopic examination of fractured surfaces of the joints showed that the surface-modified polymer essentially failed cohesively within the adhesive (Bhowmik et al, 2006). Vibra-Tite from ND Industries (Loctite Corp.) is a unique threadlocking and sealing product. All threaded fasteners tend to loosen under vibration. Vibra-Tite is a solvent solution of acrylic polymers that is brushed onto the threads and dries within a few minutes. Because of its soft, pliable nature, it seems likely that Vibra-Tite is able to cold-flow to fill all the void spaces in a threaded assembly, and then be hard enough and have enough friction to prevent the slide slippage of the threads that causes loosening. Vibra-Tite does not adhere strongly to the fasteners, allowing adjustment of fasteners and reuse after disassembly. Vibra-Tite has been used on assembly screws on the treadmill on the International Space Station and other applications (Dunn, 2006).

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Chapter 3: Review of state of the art of technology and future trends in Aeronautics The global passenger traffic is expected to increase steadily over the next 20 years by an average growth rate of about 5%. Main reasons are GDP growth, increased globalisation, and population growth (see chapter 6). To satisfy these expectations aircraft companies are looking for new technologies. Main drivers are • increased safety • reduced emissions • reduced noise • increased capacity • increased range • enhanced payload • higher speed • lower operating and maintenance costs • better overall management of the aircraft and its use Most important for reaching these aims is the development of a new generation of lighter materials. The main objective is to reduce the weight of the airframe. In addition, the materials should be corrosion resistant, damage tolerant and repairable as often as necessary. The main driving force towards lighter materials is the fact that transport costs decrease by a factor of $300 per pound of reduced weight in commercial aircraft transport. This value is 100 times as high as it is in the automotive sector. Reduced weight leads to lower costs and better ecological compatibility due to reduced fuel consumption. On the other hand, the need for lighter materials is even stronger in space applications, so that the development of new materials is mainly driven by the space industry. (Plano, 2002) The most important properties addressed by aerospace materials are strength, stiffness, impact resistance, long lifetime, toughness, ductility and lightness. This affects not only the main aircraft body and blades but also polymer components used in the interior. In the aviation industry engine improvements are also under investigation, but to a smaller extent compared to space applications. There is also a need for new sensors and miniaturised electronic components, although these developments are mainly driven by other application fields such as the automotive or information and communication sector. The results obtained in these sectors can be transferred easily to aircraft when the technologies are ready for industrial use.

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Revolutionary new nanocomposites have the promise to be 100 times stronger than steel at only 1/6 of the weight, making aircraft more efficient and able to fly faster. Current R&D is looking at improved macroscopic materials using nanomaterial additives which show the same promising properties on the macroscale as on the nanoscale. In futuristic scenarios aircraft could weigh as little as half of a conventional aircraft manufactured with today's materials. Such novel materials would be extremely flexible allowing the wings to reshape instantly and remaining extremely resistant to damage at the same time. In addition, these materials would have “self-healing” functionality. The high strength-to-weight ratio of these nano-materials could enable new vehicle designs that can withstand crashes and protect the passengers against injury. (NASA, 2001) Nanotechnology can contribute especially to reducing operating costs through lightweight and strong structural materials with the resulting weight and energy savings. In addition, functionality and reliability can be enhanced by improved functional materials and sensors. Lightweight structural materials are the main focus for applications of nanomaterials in civil aviation. Application opportunities are much broader in astronautics. These are the reasons why the aeronautics industry is actively researching the exploitation possibilities of micro and nanotech. For example, the Boeing Company has formed an alliance with Ford and Northwestern University to conduct nanotechnology research on projects of mutual interest and potential benefit to the companies' current and future products. (Boeing, 2005) Airbus is following its airframe philosophy which focuses on highest performance, the ‘maintenance-free’ airframe and environmental friendliness. Researchers at the Corporate Research Centre (CRC) in Ottobrunn and Suresnes are working in projects to use nanotechnology for this airframe philosophy. (EADS, 2007) British Aerospace has also begun to build up a basic nanotechnology capability. (Pritchard, 2004) Although nanotechnology seems to be promising for the aeronautics industry and breakthroughs are expected within the next few years, there are no nanotechnology applications in current Airbus aircraft (Oger, 2006) and this can also be assumed for Boeing aircraft. The main reason for this is the need for mature and robust solutions in aerospace applications. The aeronautics business remains extremely conservative and risk averse, making it difficult for nanotech applications to be integrated into new products. This is even more prominent for civil aircraft makers. Carrying passengers puts extreme demands on the

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qualification process of new technologies. The material has not only to prove its supremacy, but also its durability, whereby the physical properties are maintained under extreme conditions and on a long-term basis. In addition, a production process suitable for an industrial scale and a reasonable price/performance ratio is mandatory. (Oger, 2006; NanoroadSME) Although the requirements of the aerospace sector are a driving force for improvements in nanomaterials, the sector will stay a niche market for nanotechnology applications because of the small numbers of aircraft and the associated cost intensive development. In the following sections, the aspects of nanotechnology applications in the airframe, as coatings, for the engine, new sensors, and in the electrical system are discussed in more detail. Please note that, as described above, the following descriptions and examples are possibilities, none have yet been realized in civil aviation.

3.1. Airframe and components The drivers are for lighter, stronger and safer aircraft. According to a study of Lockheed (cited in Bader & Stumpp, 2006) it is not sufficient to reduce the density of a material. When reducing the weight of an element by 10% it is necessary to reduce its density by 10%, but simultaneously to enhance its strength by 35%, its stiffness by 50% and its damage tolerance by 100%

Current aircraft are composed of different materials. Besides conventional metals like steel the use of lighter metals such as titanium, magnesium and aluminium has strongly increased in the past. Higher potential for lighter structures have the use of fibre-metal composites like glare (a laminate of aluminium and glass fibres) and fibre-reinforced polymers. Recently, the increasing use of fibre-reinforced polymers in civil aircraft, e.g. the Airbus A380, has lead to a competitive advantage for the European aerospace industry. Mainly carbon fibres with diameters of a few micrometres are used for reinforcing. Fibre-reinforced polymers have the potential to reduce weight by up to 30% compared with aluminium parts and 50% compared with steel structures. In current aircraft of around 20% by weight of reinforced polymers are used, in the Airbus A380 this value will be enhanced to 25%, for the Airbus A400M fibre-reinforced blades are planned also with an increase of the polymer amount to 30%. Boeing’s concept for the new 787 Dreamliner includes an amount of more than 50% polymers measured by weight and much more than 50% by volume.

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A further improvement can be expected by substituting micrometre fibres in these composites by fibres in the nanometre range. Estimations are made that aluminium, reinforced with carbon nanotubes, can lead to a weight reduction of 60-70% compared with current fibre-reinforced polymers.

Advantages of nanomaterials are: • ultra high strength to weight ratio • improved hardness, wear resistance and resilience • thermal shock, fatigue and creep resistance • enhanced anti-microbial activity • multi-functional materials can reduce weight by reducing the

number of components Nanomaterials can enhance the properties of almost every material used in aircraft building. Fibre-reinforced polymers • Carbon Nanotubes (CNT): Hollow tubes of one (SWCNT, single walled

carbon nanotubes) or more (MWCNT, multi walled carbon nanotubes) layer(s) of graphite. The feasible reduction of the weight of aircraft components using composite materials reinforced with carbon nanotubes (CNT) can be as large as 60-70% compared to existing carbon fibre reinforced polymers (Fig.3.1).

Figure 3.1. Nanotube-Reinforced Polymer (CNTFRP) and Nanotube-

Reinforced Aluminium (CNT/Al) Composites compared to an advanced carbon fibre reinforced polymer (IM7 CFRP) composite (Boehm)

The major hurdles preventing a broader use of CNTs (not only in the aerospace sector) are the 10,000-fold increase in price compared to standard fibres and the lack of an appropriate industrial-scale production method. Technical problems include a lack of methods to achieve spatial alignment of CNTs, good adhesion to the polymer matrix and achieving a high loading rate.

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• The addition of nanoparticles (e.g. clay-like mineral montmorillonite) to synthetic resin is being studied to improve material strength. (EADS, 2007)

• Carbon-fibre reinforced polymers have a greater potential as a lightweight design than aluminium alloys, but suffer from delamination under load. The use of SiO2 nanoparticles leads to an improvement of 64% in tensile modulus, 25% more strength and 90% more impact resistance. (Bader, 2006)

Metals • Properties of metals are governed by the Hall-Petch relationship – as

grain size decreases, strength increases. Nanocrystalline materials are characterized by significant increases in yield strength, ultimate tensile strength, and hardness. For example, the fatigue lifetime can be increased by 200-300 % by using nanomaterials with a significant reduction of grain size in comparison with conventional materials.

• Nanostructured metals, particularly aluminium and titanium alloys can

improve the mechanical properties and enhance corrosion resistance. • Metals can be strengthened by ceramic fibres such as silicon carbide,

aluminium oxide or aluminium nitride. Advantages of these so-called MMC (Metal matrix composites) are a high thermal stability, a low density, high strength, high thermal conductivity, and a controllable thermal expansion. MMC have the potential to substitute magnesium and aluminium parts in the future.

Ceramics • Nanophase ceramics show an enhanced ductility and strength, and a

reduced sinter temperature. These materials can be used as thermal and oxidation protection for fibre-reinforced construction materials.

Composites

• Glare –a laminate made of aluminium and glass fibres – is as strong as aluminium but lighter and corrosion-resistant. However, it is much more expensive. The bonding between the metallic sheets and fibres can be enhanced by nanoparticles. (Nanovic)

Applications

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Applications where nanomaterials can contribute to aircraft construction are mainly in the airframe structure but also in the interior to a minor degree:

• The airframe is the main target for the use of nanomaterials, aiming at a weight reduction and therefore decreased fuel consumption and costs because of the strength of nanomaterials as described above.

• Another reason for using stronger materials is to enhance passenger comfort. For example, the cabins of airliners are pressurized to avoid the need for oxygen masks, but the onboard air is still much thinner than on the ground — typically the cabin atmosphere is equivalent to an altitude of 8,000ft. Keeping the cabin pressure at ground level, the aircraft’ aluminium bodies would have to be much thicker, making them prohibitively heavy. The new Boeing 787 will be built from a stronger carbon fibre composite, so it can allow a higher onboard pressure, equivalent to being outside at 6,000ft altitude. It is expected that as a result passengers will be far less tired. As mentioned above, nanomaterials could give rise to even stronger composite materials than those made with traditional carbon fibres, and could allow onboard pressure to be increased further. (Robbins, 2006)

• Substituting stronger material of the same weight can increase the impact resistance of aircraft skin material.

• Visionary ideas include fault tolerant and self-healing materials. It has been shown that nanoparticles dispersed throughout a material can migrate to cracks, potentially giving rise to self-healing composites (if sufficient migration occurs to seal cracks). For example experiments have been undertaken with spherical particles of about five nanometres underneath silicon oxide. With the right coating, the nanoparticles automatically migrate toward cracks in the silicon oxide. The Max-Planck-Institut für Eisenforschung is working on filled nanocapsules in zinc coatings for self-healing on cut-edges. Although these examples are not focused on aircraft applications, the results should be transferable. (Physorg, 2006)

• With regards to structural materials, nanotechnologies might enable further improvements or tailoring (e.g. gradients) of mechanical properties well beyond more conservative chemical or metallurgical approaches.

• Aircraft safety and security is also being increased through the use of new materials in the interior. One example is the development of bullet proof materials for sensitive parts, e. g. the cockpit door. High strength and lightweight composite laminates (incorporating carbon nanotubes in a variety of resins) are being investigated for use in ballistic protection and novel damping materials.

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• An important aspect for the interior of an aircraft is the need for fire retardant materials. The aim is to meet the stringent specifications demanded of materials used in aircraft interiors more cheaply and effectively than with the costly specialised polymers currently used. It has been shown that the introduction of nanoparticle additives to 5 % can lead to a huge reduction in fire risk. On the other hand nanoparticles can also act as fire accelerant, so a detailed analysis of nanoparticles used in aircraft is necessary. (FhG-IFAM, 2004)

• The Boeing 787 concept not only includes a higher cabin pressure but special filters to maintain a higher air quality. Filtration systems are on the market, which use nanoscale silver particles to eliminate undesirable odours and kill airborne health threats. It has been shown that such nanofilters kill 99.7% of influenza viruses. Up to 98% of odours were eliminated and another nano-filter eliminated all noxious volatile organic compounds. (AzoNano, 2004)

3.2. Coatings The trend is to substitute metals by reinforced polymers, which can be supported by nanomaterials. In addition to the use of nanomaterials for improving material properties of structural materials, metals can also been made more durable by applying nanostructured coatings. One example is the development of coatings for landing gear as a replacement for environmentally problematic chrome coatings. (Integran) The main target for nanocoatings is the protection of metals against corrosion, but other applications are also under discussion.

• For example, magnesium – which is one third lighter than aluminium and 80% lighter than steel – has been used increasingly in the past, but magnesium alloys are strongly susceptible to corrosion. The application of durable anodic or conversion coatings typically provide protection against such effects. Anodic coatings are tougher, harder and have better wear properties than conversion coatings, but their cost is too high for mass production. Chromate-based conversion coatings are cheaper, but the hexavalent chromium involved is both carcinogenic and a hazardous air pollutant, so that a viable alternative is urgently needed. The EU-funded NANOMAG project aims to provide an alternative by developing clean and environment-friendly nanocomposite coatings based on silicon oxide thin films that will be more economical while also offering superior resistance to corrosion and abrasion. (NANOMAG, 2003; Plano, 2002)

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Other anticorrosive materials used in aviation, are nanoscale boron oxide (Shuihu, 2003) and nano-crystalline cobalt-phosphorous coatings. (TPC, 2005)

• For repairing corrosion damage, carbon nanotube filled resins are under development. (Nanovic)

• Additional coating applications are more durable paints allowing aircraft to be repainted on a less regular basis, insulator coatings for heat and chemicals, and bio-nanomaterial coatings to keep airplane surfaces clean and free of micro-organisms.

• High performance nanocomposites of polymers, metals and ceramics, can be used for tribological coatings of aircraft platforms operated at higher temperatures. Nanocrystalline cobalt-phosphorous coatings are also being developed to provide superior sliding wear resistance and a lower friction coefficient.

• Specific surface properties could be designed in order to open new functionalities, as for instance self-cleaning or self-healing properties.

• Each single de-icing procedure of an aircraft can cost of up to 10,000 € (3sat, 2001). In principle it should be possible to remove ice from the aircraft body by an electrical current flowing through a thin conductive layer. This technique is currently under investigation for removal of dew and ice from automotive headlights (Hella, 2006).

• Scratch-resistant nanocrystalline coatings are already available on the automotive market. Research is underway for their use in aircraft windows.

• Anti-bacterial coatings using nanoscale silver are available in the clothing industry, refrigerators, and washing machines. Their use is now being investigated for aircraft cabins.

• Hard compound nano ceramic films are being investigated for the protection of propeller-blade surfaces.

• Nanocomposite polyurethane paints and fluorocarbon paints have been patented for use in aircraft. These paints should show greater durability than current paints.

• Nano paint (nano graphite, nano Teflon, nano talc powder) has also been patented for reducing friction of ship and aircraft surfaces (allowing faster speeds to be achieved). The advantages should be a very high lubricating and self-lubricating performance. (Qinghai, 2002)

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3.3. Engines Engines are still fuelled by hydrocarbons. Fuel combustion has been reduced in the past by aerodynamic improvements, by weight reduction and by more fuel-efficient engines and systems. However, the cost of aviation fuel is still a major part of airplane operating costs and further improvements in the efficiency of aircraft engines are required.

Improvements in aircraft engine efficiency can be reached by materials which allow higher operating temperatures, lower engine weights, higher pressures and increased rotor operating stresses.

• The application of high temperature nanoscale materials to aircraft engines may lead to an increase of the thrust-to-weight ratio of up to 50 percent and fuel savings of 25 percent for conventional engines.

• Nanomaterials are being applied as coatings on aircraft engine blades. Research is ongoing to manipulate the properties of the coatings down to the molecular level making them adhere more firmly to the surface of the metal blade and allowing the engines to run hotter.

• Nano-phase ceramics are being tested for use as thermal barrier coatings (TBC). Improved TBC protective coatings have wide application in aircraft engines, aero-structures, turbine engines, and chemical processing. The coating system consists of an outer layer that is chemically resistant, deposited on an underlying strain-resistant layer that can deform without cracking. Both layers are made of perovskite oxide ceramic layers. If successful, higher fuel efficiency can be reached due to longer lasting TBCs that do not peel off. (Navy, 2006)

• The enhanced creep, fatigue and sulphidation resistance of grain boundary engineered components is expected to significantly increase the time between engine overhaul/refurbishment.

Because of the high surface area, nanoparticles can act as very efficient catalysts, even for liquid and solid aerospace engine fuels. Fuels used at present can be improved by the addition of nano-sized energetic particles, which allow a higher combustion temperature, faster energy release rates, a shortened ignition delay, shortened burn times resulting in more complete combustion, a greater flexibility in designing new energetic fuel/propellants, replacing inert or low-energy gellants, and a rapid energy release.

• Aluminium nanoparticles are used with liquid jet and rocket fuel to increase the propulsion energy.

• Iron oxide nanoparticles can act as a catalyst for solid propellants.

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• Nano-sized energetic metals and boron particles possess desirable combustion properties such as a high combustion temperature and fast energy release rates. (Kuo, 2003)

A comprehensive understanding of the important characteristics of nano-sized particles to reach a desirable performance and ease of processing is still not available. There is still much to learn about the correlation between physical and chemical properties and measured combustion performance.

Aircraft turbine engines are very flexible in the kind of fuel that they can burn (Valentine, 2006). Cleaner and alternative fuels may help in reducing harmful emissions. Examples under discussion are hydrogen or cryogenic fuels. Problems are a suitable industrial production technique of hydrogen and suitable storage technologies. Nanomaterials are being widely investigated for their ability to store hydrogen and other gases and liquids because of their high surface-to-volume ratio.

A more revolutionary vision is the use of electrically powered propellers. High-density energy-storage technologies are needed to make this a reality. The vision is based on superconducting energy-storage systems. Advances in nanotechnology could enable superconductive materials to eventually be manufactured at a cost that could justify their application in airliner propulsion. (Valentine, 2006)

3.4. Sensors In addition to chemical and optical sensors, further sensors are needed in aircraft for measurements of velocity, acceleration, position, temperature, and flow properties. • The conductivity of wires with diameter of a few nanometres is very

sensitive to small changes in electrochemical potential. Because of this, they can be used as very sensitive sensors for different gases. Nanosensors can be used for the early detection of fires in the cargo compartment of aircraft. The sensors are based on nanoparticles of metal oxides. Similar sensors can be used for the detection of biological and chemical toxins.

• Gyroscopes are used to track an airplane’s position. Microscopic structures are now being built into chips that perform the same function at far less weight and space. It could be imagined that nanostructures can lead to further reductions in weight and space. Nanocrystal films of iron-germanium can work as magnetic sensitive material for Hall elements for the measurement of angles and elongations.

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• The enhanced use of composite materials leads to the need for a structural health monitoring system, because traditional methods for testing metallic structures, like eddy current testing, cannot be used for insulating materials. For identifying damage within advanced composite materials, a network of carbon nanotubes or other nanowires can be used, which detects damages by a reduction of the network conductivity. Airbus for example is exploring piezoelectric paint made of a lead-zirconate-titanate nanopowder; however this is still at a laboratory stage. This paint could work as a very precise sensor for information about vibrations, defects or impacts on an aircraft surface.

• Advanced concepts using networks of interoperable micro and nanotechnology sensors for accurate event detection and identification, and for long term monitoring applications are discussed for future aircraft/spacecraft health monitoring systems. In this context systems for miniaturized power sources and wireless communication are also required. (CANEUS, 2004)

3.5. Electrical/electronic components and hardware Nanoelectronic systems are being developed for the Information and Communication sector. The results can be used also for applications in aircraft. Again, the aviation industry is not the main driver and applications in astronautics are much more ambitious because of stronger weight constrictions and a harder radiation environment. • The main driver in the aviation sector is an improved comfort for

passengers. For entertainment systems, improved flat screens and miniaturized and energy-saving data storage systems would be helpful. For example, flat screens utilising carbon nanotubes have been developed, which have lower energy consumption, a broader viewing angle and a lighter display compared with LCD displays.

• Integrated nano-electronic systems will allow the opening of “the office

and home in the sky”. • Weight savings could not only be reached by savings in the aircraft

frame but also by replacing heavy copper wires in aircraft by nanotube-improved plastic wires.

• Nanotube-enhanced conductive plastics can be used for electrostatic

dissipation in electronic devices and electromagnetic-wave shielding. • A research project, led by the Boeing Research and Technology Centre

in Madrid is aimed at exploring the use of fuel cell technology for future aerospace applications and for providing auxiliary power - for things

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such as air conditioning and lighting on its aircraft by 2015. The application of fuel cells has the potential to save up to 1% of jet fuel, which is a large value considering that one Boeing 777 uses about half a million kilograms of fuel every year.

3.6. Others • For hydraulic uses, better lubricants and safer nano-fluids are being

developed.

• For a reduction of process times of composites, new technologies are making use of microwaves to decrease the time needed for curing. Ceramic nanoparticles are included in fibre composites, with the aim of increasing strength and surface quality.

• In the longer term, active noise control techniques may benefit from new knowledge on micro and nanotechnologies and could allow aircraft noise to be reduced further. (ACARE, 2004)

• The windows in the Boeing 787 will not have blinds, but are made from electro chromic glass, which dims at the touch of a button.

• In the ceiling, the colour and brightness of hundreds of LEDs can be adjusted to give a sense of daylight, or a starry night sky. The aim of these lighting effects is to adjust the body clock to the time of day at the destination. (Robbins, 2006). OLEDs also allow new lighting and display devices for aircraft cabins. Further advantages are cost and weight savings and the opening of new application fields. (Diehl, 2005)

3.7. Conclusion To conclude, nanomaterials and nanoelectronics are being investigated for uptake in aircraft on a large scale. Foreseen benefits include cost reduction, reduced environmental burden and enhanced passenger comfort. Uptake of nanomaterials and nanoelectronics in aircraft may be slower than in other sectors, but there is clear interest from the industry.

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Chapter 4 Review of state of the art of technology and future trends in Spacecraft

4.1 Introduction The space sector deals with all the technologies associated with travel outside the earth atmosphere. Different types of spacecrafts exist to achieve specific goals in space exploration. Spacecrafts are also developed for both military and civilian applications. This section will cover civilian applications. The spacecrafts have been classified as: A rocket is a vehicle that obtains the thrust from the ejection of fast moving fluid of a rocket engine. Other than military applications, rockets are usually used to launch satellites or other payloads.

A shuttle is also a vehicle used to transport humans into space. A shuttle can be used to transport humans from the earth to an orbital space station or can be a manned mission where astronauts have to live in the shuttle.

A space station is an artificial structure designed for humans living in outer space. So far only low earth orbit (LEO) stations are implemented, also known as orbital stations.

A satellite is an unmanned spacecraft used for several scientific applications such as earth observation and planetary exploration. The satellite is also used for commercial applications such as communication and GPS.

Non-orbital spacecrafts called ‘probes’ are used for deep exploration of the universe. The importance of the space sector can be emphasised by the number of spacecrafts launched. In the period from 1957 till 2005, 6376 spacecraft have been launched at an average of 133 per year. There has been a decrease in the number of spacecrafts launched in the recent years with

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78 launched in 2005. Of the 6376 launches, 56.8% were military spacecrafts and 43.2% were civilian. 245 manned missions have been launched in this period. 1674 communication or weather satellites were also launched1. The remaining spacecrafts launches have been exploration missions. The space sector has been a strategic field for all the industrial nations. Space exploration is the oldest human dream and the present national space programs are very ambitious (e.g. Mars manned flights, extra solar system exploration2). As spaceflights become common, commercial applications are expected to present colossal potential opportunity for communication, GPS and space tourism companies. The following factors are considered to be pushing new technology development in space-

• The ambition of national space programs to enhance their space knowledge such as that of NASA to push human frontiers to the moon and beyond by longer exploration. This goal will require the development of autonomous spacecraft and in the case of manned mission consider technical developments to sustain life in space. Energy generation and storage sub systems, life support, health management knowledge have to be developed to meet the challenges of harsh environment in space.

• The development of commercial space applications will be faced with the problem of decreasing costs. As costs are considered proportional to weight, research will be required on commercial application based on decreasing both structure and payloads weights by the use of lighter materials and integrated systems such as Nano and Pico satellites.

Technological improvements can bring solutions to achieve those objectives. But new technologies are also being developed to face traditional space constraints –

• Facing high levels of radiation with suitable materials and electronics.

• Facing extreme temperatures and temperature variation (e.g. between the extreme cold of Mars, Titan or Pluto exploration and extreme heat of atmosphere re-entry)

• Facing mechanical constraints of launching by suitable engines and structures.

As nanotechnologies cover all the scientific fields implicated in spacecraft enhancements (materials, electronics, energy), studying them for

1 The spacecraft encyclopedia, http://www.sciencepresse.qc.ca/clafleur/spacecrafts-index.html 2 NASA strategic plan, http://www.nasa.gov/pdf/142303main_2006_NASA_Strategic_Plan_sm.pdf

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spacecraft applications makes sense in order to understand tomorrow’s spacecraft. Nanotechnology is the development at the atomic, molecular or macromolecular levels, in the length scale of approximately 1 - 100 nanometre range, to provide a fundamental understanding of phenomena and materials at the nanoscale and to create and use structures, devices and systems that have novel properties and functions because of their small and/or intermediate size3. The objective of this chapter is to describe nanotechnologies state of the art for spacecraft applications and to analyse future trends in the coming years. As nanotechnologies are still an emerging field, their use is very limited in space but after analysing space agencies research, publications and reports it appears that several advanced researches are focused on nanotechnologies for short-term applications (expected by 2008). As the different technologies developed can find applications in various missions (commercial / scientific) and on various spacecraft (lighter materials are important for satellites as well as for rockets), the analysis of the use of nanotechnologies in spacecraft field will be done by technology: - The three first parts will describe innovation that could find applications in all the spacecraft such as nanotechnologies for materials, electronics and energy. - The fourth part outlines manned flights and the potential applications of nanotechnologies for on-board life support management. - The fifth part describes satellites and science payloads and the potential of nanotechnologies in making them more efficient. - And final part is a review of the potential of nanotechnologies for futuristic visions like the space elevator.

4.2 Materials Most of the progress in nanotechnology has happened due to the discovery of many novel nanostructured materials and the subsequent characterisation of their electronic, electromechanical, electrochemical, mechanical, chemical, optical and magnetic properties for a variety of applications. These new properties represent an important interest in spacecraft applications because they address the design constraints in achieving the space goals.

• New mechanical properties can bring solutions to mechanical constraints of launching.

• New optical properties can increase radiation protection of space structures.

3 NSF definition, http://www.nsf.gov/crssprgm/nano/reports/omb_nifty50.jsp

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• New thermal properties can solve the problem of extreme temperature variation, not only for the structure but also for components, because at that level the wall of temperature is a very stringent factor.

• New electronic properties can allow building materials with integrated sensors (e.g. to detect materials cracks) or materials for electronic components. Several new sensors such as infrared sensors, gas and pollutants sensors can also be created.

• Finally materials nano structured can allow the construction of lighter structure and the development of nanocomposites.

Nanoscale engineered materials built with basic nanoelements such as nanoparticles, nanotubes, or with nanotextured, nanoporous 3D specific network can present interesting characteristics for spacecraft applications. The nanomaterials with new properties may be used in spacecraft (rockets, shuttle, satellites) and most of the applications described here concern structural materials.

4.2.1. Nanoelements The nanomaterials considered are in fact nanoelements such as nanoparticles or nanotubes incorporated into different kind of materials (polymer, composites, coating). That’s why a rapid description of the two main elements found in nanomaterials for space applications seems important. Nanoparticles Nanoparticles were the first discovered nanoelement and so their engineered processes are the most controlled. They can be used in several devices (as bulk or surface) for materials or electronics. They bring new properties to existing materials e.g. creation of specific optical properties with the addition of TiO2 nanoparticles. According to the control of their engineering, nanoparticles are already used in mass production materials like in automotive industry. Indeed, the tire industry has been using SiO2 nanoparticles in order to improve mechanical and thermal properties for a few years. Due to their high mechanical strength and resistance against heat and radiation, nanoparticle reinforced polymers, have potential applications in various components in space as lightweight structural materials, housings of solid-propellant rockets, as heat protection material, electrical isolations or fire protection applications. The early applications are already emerging

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in the space sector. In a SBIR project of NASA, nano-crystalline aluminium alloys were developed for space applications by the company DWA Aluminium Composites in co-operation with different US-American aerospace companies. This development aims to facilitate formability of materials through super plasticity generated by reducing the melting points and sintering temperatures to 30% (VDI Technology centre, 2003). Carbon nanotubes A carbon nanotube is a sort of carbon nanofibre. Carbon nanofibres are cylindrical nanostructures with graphene layers arranged as stacked cones, cups or plates. Carbon nanofibres with graphene layers wrapped into perfect cylinders are called carbon nanotubes. The carbon nanotube is the emblematic element of nanotechnologies because it is the most promising. Due to their unusual properties (elasticity, stiffness: about 1 terapascal, compared with about 10 gigapascal for conventional carbon fibre and 1.2 gigapascal for high-carbon steel), carbon nanotubes possess numerous application potentials in space, among other things within the ranges of space structures, thermal control devices, sensor technology, electronics, gas storage and biomedicine. A substantial part of the nanotechnology programme of the main space agencies (NASA, Aerospace Corporation4, ESA) is based on the development and application of carbon nanotubes based material improvements. In particular there is a huge potential for mass savings in space structures, which represents one of the main goal of futures spacecraft. Another further advantage of carbon nanotubes based materials is the possibility of creating monitored materials. According to the electrical properties of carbon nanotubes, the changes of the mechanical properties of the material can be indicated through changes of the electrical resistance and so possible damages could in principle be easily detected by simply monitoring the electric conductance of the material (VDI Technology Centre, 2003). Despite the exceptional value for spacecraft technology, the related structural applications of multifunctional nanotubes are to be expected rather in a medium term time horizon due to their high price and problems with the scalability of production processes. Indeed nanotubes and other structural materials discussed above are not yet being produced in large enough quantities to be cost effective for bulk applications (the

4 Aerospace Corporation is an independent US research centre for United States Air Force and the National Reconnaissance Office. It also has links with NASA, Jet Propulsion Laboratory, Air Force laboratories and California State

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average price is about $500 per gram and the average quantity production is about 100g per day). The second problem is concerning the transfer of the molecular properties to macroscopic materials are still unsolved, e.g. the dispersion of carbon nanotubes but also of any other kind of nano charge (more specifically when they are hydrophobic) in composite matrices or spinning of carbon nanotubes to macroscopic fibres. Another problem with the production of carbon nanotubes composites, e.g. reinforced polymers, is the alignment and the adhesion of the carbon nanotubes in the matrix. Carbon nanotubes tend naturally to agglomerate, so that the loading rate of carbon nanotubes is limited to a little weight percentage and problems of viscosity appear at high loading rate. But carbon nanotubes have the potential to revolutionize several space technologies. NASA has numerous research programmes based on an optimization of the carbon nanotubes production process and also on the functionalisation of those nanotubes to integrate them in components. A partnership between NASA and Idaho Space Material (ISM) (NASA, 2006) will allow NASA to benefit the high rate carbon nanotubes production (50g per hour) to develop next generation metals, composites, polymers and ceramics.

4.2.1.1. Materials using nanoelements

4.2.1.1.1. Polymers A polymer is an assembly of large molecules consisting of repeating structural units, or monomers, connected by covalent chemical bonds. Nanoparticles can be introduced in polymer to improve their electrical, thermal or mechanical properties. According to VDI, suitable nanoparticles such as silicates (in particular montmorillonite clay), POSS (Polyhedral Oligomeric SileSquioxanes) are under consideration. Epoxide, nylon, polyphenole or polyimide can be used as polymer matrix. The properties of composites that can be significantly improved are thermal and flame resistance, moisture and chemical resistance, decrease permeability, charge, dissipation and conductivity. Nanoparticle reinforced polymers is being developed by NASA through the SBIR program. NASA has conducted the initial qualification tests of nanoparticles reinforced polymers for space application.

4.2.1.1.2. Composites Composite materials are being produced by mixing nanotubes, nanowires, nanoparticles, fullerenes in polymer, carbon, ceramic, or metal matrices. Such composite materials can provide significant enhancement in the

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thermal conductivity, directional anisotropy, radiation absorption, and structural reinforcement capabilities. Major reductions in the overall system mass are possible with the use of nanostructured thermal protection and radiation structure materials. Nanoparticles and nanopowders as reinforcing composites: Thermomechanical properties, fracture toughness, fracture toughness and formability can be improved by using nanoscale ceramics. The use of nanopowders of oxide nanopowders Si3N4, SiC, TiCN and non-oxide nanopowders Al2O3, SiO2 can reduce the sintering temperature and the consolidation time of ceramic material. Nanostructured ceramic composites can provide thermal and oxidation protection for construction material. High strength transparent bulk ceramics for applications as external surfaces and skins for spacecrafts and window is also under development. (VDI, 2003) Ceramic fibres reinforced metals can replace magnesium and aluminium in different structure. Material such as silicium carbide, aluminium oxide or aluminium nitride can be potentially used in spacecrafts. As has been reported, the strength of metal matrix composites could be increased up to 25% through nanostructuring and beyond that, super plasticity and a better resistance against material fatigue can be obtained in comparison to conventional metal matrix composites (VDI, 2003). Different research activities can be noticed in the frame of the SBIR programme of NASA, CANEUS concept paper and Aerospace Corporation activities. Further development of nanocomposites will be to make them tuneable, adaptive, self-healing and stress smart sensing systems. These materials will optimize considerably space travel by increasing functionalities in spacecraft systems and vehicles while reducing mass, size and power consumption. Carbon nanotubes / nanofibres in polymer: Most of the research on composites is based on the incorporation of carbon nanotubes into polymer matrix. NASA investigates carbon nanotubes integration in polymer in its laboratory TIIMS5. Research aims at purifying and functionalizing carbon nanotubes to enable new nanotube polymeric and ceramic composites that have electrically conductive, switchable molecular properties, including nanoshells (spherical core of a particular compound surrounded by a shell with a thickness of a few nanometres).

5 Texas Institute for Intelligent Bio-Nano Materials and Structures for Aerospace Vehicles: http://tiims.tamu.edu/research/nanomat.html

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Aerospace Corporation shows that cyanate ester trimers interact strongly with the surface of the single walled carbon nanotubes. Experiments have shown that when carbon nanotubes are fully dispersed in cyanate-ester resin, at concentrations of only 0.5 percent by weight, the modulus of the cured polycyanurate matrix is approximately doubled. This nanoreinforced resin can improve the resin-dominated properties such as shear strength of carbon fibre polycyanurate composites used in space hardware for stiff, lightweight structures. Carbon nanotubes thermal characteristics have also been tested to create new polymer properties. Experiences show that the insertion of nanotubes into the polymer matrices increases the thermal expansion coefficient of the material by 40 to 60 percent above glass transition temperature. This also enhances the thermal diffusion coefficient by about 30 percent (CANEUS, 2002). These characteristics of the composite, as opposed to the bare polymer matrices, are expected to be useful during the processing steps above glass transition temperature. The mechanical strength and stiffness characteristics of the polymer matrices are also found to increase by about 30 to 50 percent on mixing of 5 to 10 percent of nanotubes at room temperature. Enhancing thermal properties can be useful to protect structure of space extreme temperatures. Another research axis is the introduction of carbon nanofibre in carbon fibre reinforced plastics (CFRP). Mechanical and electrical properties of the CFRP are enhanced proving their efficiency in ultra lightweight load-bearing structures for harsh environmental conditions. Carbon nanofibre doped epoxy mixtures are used as a matrix material for the preparation of unidirectional CFRP. The mechanical characterization of the doped CFRP showed remarkable increase in the fracture energy of the laminates and also higher elastic and storage modulus in comparison with the non-doped CFRP. CANEUS is also investigating this field since 2004 with possible applications in 2007 in the frame of the project “Nanofibre Composite Materials for Load Bearing Structural applications”. The use of carbon nanofibre as nano-sensors for the damage detection within the matrix material of the CFRP is investigated. Its application is non-destructive damage detection in CFRP during mechanical loading that is a key parameter in space structure (Kostopoulos et al., 2005). Investigations are also made in the frame of a CANEUS project to build smart composites. A variety of micro-nanotechnologies-based sensors and actuators are embedded within these composites, creating multi-functional, “smart” materials. Numerous potential applications exist for such multi-functional structures or failure monitoring.

4.2.1.1.3 Coatings

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Coatings are used in spacecraft as structure protector or to enhance some properties of the material structure. Nanotechnologies allow the building of a lot of new coatings like smart coatings or with attractive new properties like hardwearing, thermal electrics isolating, optical properties. Most of the research on coatings is currently focused on the enhancement of electrical and thermal properties of existing structures. Conductive nanostructures could be used as dopes within the plasma sprayed white ceramic optical coatings. Nanostructures have the unique property of being small enough not to significantly impact optical properties in small concentrations (<1%). Thus, a percolate network of conductive nanostructures such as carbon nanotubes or conductive oxide nanowires can be incorporated into the coatings to improve conductivity. Transparent films of carbon nanotubes can also be used as a conductive coating over the ceramic coating to mitigate charging effects e.g. on the heat shield (Kao, 2006). Electrical conductivity of thermal blankets used on most spacecraft surface is a key point of a rocket structure because it prevents the build-up of electrostatic charges that could lead to potentially harmful discharges. The conducting indium-tin-oxide coatings typically used on blankets can crack and oxidize which reduces their conductivity and can create electrostatics charges. That’s why a transparent polymer blend with sufficient bulk conductivity and environmental stability to mitigate surface charging on satellites was developed by Aerospace Corporation. The material polyaniline or polyimide blend could eliminate hundreds of straps used to ground the conductive front surface of the blankets to the spacecraft. They now investigate the use of fluorinated polyaniline in the fluorinated host material polyimide conducting to create polyaniline nanofibres in order to improve optical transmittance. The use of carbon nanotubes as coating can also enhance thermal conductance of metal-metal contacts by increasing the number of contact points, using a high density of nanometre-sized contacts. This task can be accomplished by coating one of the interfaces with multiwalled carbon nanotubes. When pressed against a solid material, many of the multiwalled carbon nanotubes make contact to the material, and the number of contact points is increased dramatically that generates thermal conductance improvements over both metal-metal contact (Sample, 2005).

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4.2.2 Materials conclusion Nanoscale materials represent a major stake for spacecraft because of the opportunity they bring to build new structures with specific thermal, electrical, optical characteristics, stronger and cheaper structure. Major space agencies are engaged in research concerning nanomaterials with new properties and some of them can nearly find applications. The following table summarizes the different nano applications for materials in space under study:

Technology Characteristic Interest6 Perspective Nanoparticles reinforcing polymers

Improve thermal, flame, resistance; decrease permeability, charge dissipation

++ Short term (in test)

Nanoparticles reinforcing composites

Improve thermo mechanical properties

+ Short term

Carbon nanotubes reinforcing composites

Improve thermo mechanical properties; radiations resistant

+++

Middle term

Carbon nanotubes reinforcing coatings

Improve thermo mechanical properties; allow creation of electric properties like failure detector

+++ Middle term

Smart materials Integration of electronic component to create new functions

++ Long term

Notice: research on carbon nanotubes integration seems the most promising but carbon nanotubes manufacturing and integration into an existing structure is still not totally controlled. This research will find applications in the longer term than nanoparticles integration. Finally, one of the key factors of futures applications of nanostructured materials for spacecraft will be the elaboration of efficient characterisation and modelling tools. Before any material can be specified for a space application it must endure rigorous testing and analysis to determine optimal processing conditions and ensure reliable performance and security in the hostile space environment. This is all the more true with nanoscale materials because of their small size and specific characteristics. Secure modelling processes and rigorous tests ensure crew security in the case of manned flights and decrease the financial risks of a failure in space (Kao, 2006).

4.3. Electronics Electronics is everywhere on a spacecraft. It controls all the vital systems of the vehicle (orbit, attitude determination, communication between the

6 +: normal ; ++: strong interest ; +++ : very strong interest

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different parts of the vehicle, energy transformation) and all the science payloads. The electronics industrial sector is a very innovative sector with a huge market potential and so the study of nanotechnologies incorporation into electronics devices represents a real stake for its actors. Indeed nanotechnologies promise enhancement of actual electronics devices properties reducing their size. Thus nanotechnologies applications for spacecraft electronics are essentially spin off from ground electronics sector because they pursue the same goals: decreasing price, increasing performances. And nanotechnologies show promises to achieve these goals by the use amongst others of carbon nanotubes. Nevertheless it is important to note that nanotechnologies in spite of their prefix “nano” don’t represent a huge potential for miniaturization. Big advances were made by the implementation of MEMS in several sub-systems and even though NEMS are in development they are not very relevant for the mass saving in big spacecraft. The only specific constraints of spacecraft that can influence the development of space specific nanotechnologies for electronics, is the exposure to highs rates of radiation. For this specific aspect the best technologic answer is carbon nanotubes that show natural high radiation resistance properties. Finally an important aspect of nanoelectronics for spacecraft as well as for nanomaterials will be modelling and characterisation of electronics devices. It will be useful to detect and anticipate failures due to space harsh conditions. It is all the more important as electronics devices use nanotechnologies because some characteristics they engender are not foreseeable.

4.3.1 Carbon nanotubes for transistors Carbon nanotubes have potential to become the base of almost electronics devices for spacecraft. Not only do they present exceptional conductive characteristics but they also have a non-negligible advantage for space use: their radiation resistance. A recent study of Prof. Kwanwoo Shin at Sogang University showed that: First, electronics device became more radiation tolerant when their

dimensions are reduced. Secondly, proton irradiations have no effects on the electrical

properties of carbon nanotubes based field effect transistor. Experiences were made with carbon nanotubes based field effect transistors exposed to 10-35 MeV proton beams with a fluency of 4.1010 – 4.1012 cm-2 that is comparable to the space environment. None of the

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devices that were fabricated for the experiment exhibited any significantly altered electrical changes before and after proton irradiation (Hong et al., 2006). But electronics devices containing only carbon nanotubes are difficult to build and cost effective. Moreover the quality control for the carbon nanotubes fabrication and the large contact resistance are two major issues that will remain problematic in the coming years. So the current most advanced researches concern hybrid Si approaches in merging carbon nanotubes based devices and structures with traditional silicon-based technology.

4.3.2 Memories / Data storage With the increasing number of on-board analysis systems coupled with the lengthening of space flight, memories have to increase their storage density decreasing mass memory. They also have to face space constraints like others electronics components i.e. extremes temperatures, radiations, mechanical constraints. “Nanotechnologies offer potential in the development of new non volatile working memories for computer systems, which will compete in the future with conventional memory chips like DRAM.” (VDI, 2003) Even expected dimensions of dynamic random-access memory (DRAM) are to be 45 nm by the year 2010 and 18 nm by 2018 (Ives et al., 2005) a range of concurrent technologies are in development “like Millipede (micromechanical device with an array of nanoscale read/write/erase tips based on scanning probe technology developed by IBM),” (VDI, 2003) ferroelectric (FRAM memory based on the ferroelectricity of certain crystals), biological memories, carbon nanotubes based memory and magneto electronic (MRAM) storage technologies. The three lasts represent the main potential applications for spacecraft. Biological memory Memories can be realized by making use of biological molecules (proteins, DNA). Bacteriorhodopsin (bR) is one of the molecules intensively examined for memory applications. At present efforts are made on genetic mutations of bR in order to stabilize individual configurations of the protein for increasing the data stability. Porphyrin is another molecule that can be used as memory. Zettacore Company is currently

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developing this technology. Experiments were also made with data storage on diamonds with Fluorine and Hydrogen atoms on its surface. This structure increases data quantity stored by 107. MRAM This magneto electronic storage technology presents several advantages for space application such as low energy consumption, inherent radiation resistance and suitability for high temperature application. (VDI, 2003) The use of spintronics in this field represents conception advantages and potential size decreasing. NRAM NRAM is carbon nanotubes based memory, high-density non-volatile Random Access Memory. NRAM has the potential to serve as universal memory replacing all existing forms of memory, such as DRAM, SRAM and flash memory. Nantero is developing this technology and announce in 2006 the routine production of carbon nanotubes for their memory applications7. Even if applications are expected in a middle-term carbon nanotubes based memory represent a huge potential of spacecraft applications because of their space radiations resistance.

4.3.3 Nanocharacterisation Impacts of defects on electronics devices geometries are always critical and the effect at the nanoscale is amplified and more difficult to detect with respect to manufacturability and reliability of these devices. New and innovative uses of advanced analytical techniques are needed that allow imaging, visualization, and detailed examination of every part of the features of interest at the nanoscale. That’s why The Aerospace Corporation created an innovative tool for failure analysis at the nanoscale. This NANO-3DI technique is a special FIB milling technique that can remove material in slices less than 2 nm thick using a standard ion beam roughly 30 nm in diameter. This innovation involves using the change of SEM image contrast and brightness caused by removal of surface carbonaceous deposit as an end point. Thus, the process of cutting and imaging can be repeated at nanoscale increments until the entire 7 See: http://www.nantero.com/pdf/Press_Release_11_06%20.pdf

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structure containing the features of interest is physically deconstructed. It can then be digitally reconstructed from the images taken after each cut (Ives et al., 2005).

Figure 4.1 : NANO-3D, Aerospace Corporation

http://www.aero.org/publications/crosslink/fall2005/03.html

A complementary approach is to prevent geometrical defects by performing simulation software.

4.3.4 Electronics conclusion Nanotechnologies in electronics components are not yet available for space missions even if they promise several applications especially in facing space radiation. As electronics is not the most current strategic aspect of space researches evolutions in nanotechnologies applications for spacecraft will mainly depend of progress made in the terrestrial electronics sector. The following table summarize the different nano applications for electronics in space under study:

Technology Characteristic Interest Perspective Carbon nanotubes for transistors

Space harsh conditions resistance (radiations)

+++ Middle term

Carbon nanotubes based memory

Space harsh conditions resistance (radiations), data storage increase

++ Middle term

MRAM Space harsh conditions resistance (radiations), data storage increase

++

Middle term

Biological memory Space harsh conditions resistance (radiations), data storage increase

+ Long term

Space research is more focused on applied electronics like various sensors that are developed in their own parts. Finally modelling and characterisation is the most active sector of space research in electronics because it represents a relevant stake to pursue the “zero failure” objective of main space missions.

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4.4. Energy generation and storage Spacecraft electrical power subsystem (EPS) typically provides four basic functions: power source, energy storage, power distribution and power regulation and control. The energy problematic is common to all the spacecraft. Rockets and shuttle need huge propulsion energy for launching using propellants; and satellites need adapted propulsion systems smaller with high energy conversion rate. All spacecraft also need efficient energy storage and conversion systems during flights for their orbiting and their other on board subsystems. This subsystem is a key component for current space stakes because smaller energetic systems, with better outputs can allow spacecraft to be more autonomous and so to stay in space for farther missions. Autonomy improvement is also very important in the case of emergencies situations and can be determinant to save a mission. Weight and size decrease with efficiency increase to avoid self heating of electrical power subsystem also make cheaper vehicles. Nanotechnologies applications in the range of electrical power and energy storage can improve batteries and fuel cells as well as photosensitive materials for high-efficient solar cells. Nanotechnologies can also be used to optimize energy generation boosting current propellants or for electric propulsion where they can be used as cold cathode to emit electron to neutralize flux of charged particles.

4.4.1. Propellants Propellants are typically a power source essential for rockets or shuttles. As propulsion subsystem is an energy liberation component, its characteristics are the need of a huge energy generation in a very short time that implies optimized energy storage and a high discharge rate. Nanotechnologies can be used to enhance current propellants essentially with the introduction of nanoparticles. Propellants usually used for space launching are ammonium per chlorate (NH4ClO4). The American Institute for Aeronautics and Astronautics as well as SNPE8 are currently exploring ways to improve those using nanoparticles of Aluminium. The most common formulation is aluminium nanoparticles mixed with molybdenum trioxide (MoO3) or bismuth trioxide (Bi2O3). The aluminium particles sizes range between 60 and 120 nm and experimentally measured combustion wave speeds varied between 420 and 460 m/s. Combustion wave speeds in excess of 1km/s with an under

8 SNPE is a chemical group specialised in explosives, energetic materials. http://www.snpe.com/uk/index.asp

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pressure of several hundreds atmosphere. Results indicate that burn rate increased with decreasing particle size. Recent advances in particle synthesis technology have allowed aluminium nanoparticles to be produced in commercial quantities. Thus, the issues of volume production, economics and quality control have reached a level of maturation such that the companies are now offering standard product. At the same time significant progress has been made toward understanding of the unique combustion processes of nanoaluminium and its various formulations such as Metastable Intermolecular Composites (MIC also called superthermite or nanothermite; it refers to an important subset of nanoenergetics). Others research is turned to ion thrusters like Boron Argon or Xenon. But they are still expensive and versatile which limit their use. Aluminium powder has been used as an additive to propellant and explosives for decades; that is why nanoparticles of aluminium appears to be a promising alternative to traditional aluminium powder. It is more and more envisaged for mars return mission to use carbon dioxide (most abundant component in Mars atmosphere) as an oxidizer for metal nanoparticles (Al).

4.4.2. Solar cells Solar cells appear to be one of the most promising energy production systems. Technology is quite well known but progress has to be made in the range of energy conversion and durability of the collectors under space conditions (radiation, heat and corrosion resistance). The use of nanomaterials is expected to significantly increase the efficiency of solar cells. Anti-reflective or self-cleaning coatings and collectors can also improve the efficiency of converting solar energy to electric power. (VDI, 2003) Researchers from Georgia Tech are working on ways to mimicking lotus self-cleaning coatings. With NASA they are developing a way to use carbon nanotubes bundles to create the surface bumps needed to prevent dust accumulation on the surface of photovoltaic cells that can decrease the energy conversion rate (Toon, 2006). At present the most efficient solar cells for space applications are based on III/V-semiconductors such as GaAs and InP and have a conversion efficiency that can reach 40% with triple junction cells. Conversion efficiencies of over 50% may be possible with such compound semiconductor solar cells (Aroutiounian et al., 2001). The conversion efficiency of solar cells may be improved by using semiconductor quantum dots. (VDI, 2003) The principle is to incorporate a layer (or layers of different sizes) of quantum dots that absorb in a region outside that of the usual

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photovoltaic device. Theoretically studies have predicted a two-fold improvement in efficiency over conventional device structures (Luque and Martí, 1997). This method of device improvement relies upon the physics of the quantum mechanical "particle in a box". Each nanocrystalline dot behaves as a potential well with energy levels that are quantized and inversely related to the size of the well. By modifying the size of the particle, the absorption energy of the dot can be tuned to a region where it will be complementary to the existing cell properties (NASA, 2002). Although the quantum mechanical dots contribute to cell output by providing an intermediate band, they do not require current matching. In this respect, quantum mechanical dot devices represent an alternative to multi-junction devices. As the quantum dots synthesis process is still not well controlled, the problems of quantum dots integration in solar cells are both the synthesis of quantum dots, their integration in an exogenous structure and the potential toxicity they represent during their manufacturing.

Figure 4.2 : Intermediate-band gap solar cell, NASA Glenn research centre

http://powerweb.grc.nasa.gov/pvsee/programs/thinfilm/tfg_nano.html

Organic solar cells can be potentially used in spacecrafts. The advantage of organic solar cells is the low cost of manufacturing as compared to conventional solar cells. The main disadvantage at this stage is the low efficiency of the device. Research on different types of organic solar cells including the Graetzel cell continues. (VDI, 2003) The only constraint of solar cell is the necessity of sun exposure to generate energy. It implies increasing research in efficient capacitors to store energy that can be released during a night phase. Capacitors like “nanocaps” could be realized by metallic nano-electrodes with ultra thin pseudo capacity or nanoporous carbon aerogels.

4.4.3. Fuel cells “Fuel cells represent an efficient method for chemical energy conversion and possess substantial application potential in space and moreover re-usable spacecraft due to their clean operation and their compactness.” (VDI, 2003) Nanotechnologies offer different possibilities to increase the conversion efficiencies of fuel cells, in particular within the ranges of

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catalysts, membranes and hydrogen storage, which in many cases is critical for the employment of fuel cell technology in space. Direct methanol fuel cells (DMFC) are one platform for generating energy. DMFC used a catalyst to convert methanol fuel to hydrogen. The poisoning of the catalyst by carbon monoxide is one of the main obstacles. This can be improved by the use of metallic nanoparticles or ceramic nanopowders. Fuel storage is also considered to be a problem in implementing fuel cells (VDI, 2003). The other type of fuel cell is hydrogen fuel cells. They provide higher power density and double conversion efficiency compared to DMFC. The critical problem with hydrogen fuel cells is hydrogen storage that prevents the use of hydrogen fuel cells power sources. Different nanomaterials were tested for hydrogen storage due to their increased active surface area but their energy storage is still inferior to that of carbon nanotubes. Indeed due to their hollow tubular nature, carbon nanotubes have a relatively good hydrogen retention rate (4-5% under very low temperature < 100°K) that is why several space agencies (American Institute of Aeronautics and Aerospace, NASA) investigated the use of carbon nanotubes to enhance current hydrogen storage system. Carbon nanotubes can also be used as anode materials, solid polymer electrolyte additive, active cathode material, bipolar plate interconnect in both hydrogen and direct methanol fuel cells. The use of carbon nanotubes allows facing the high price of platinum and also the problem of radiation degradation. But several problems appear with the creation of this kind of materials like with securing bulk amounts of small-diameter nanotubes. Moreover carbon nanotubes didn’t appear as cost relevant as it promised. That’s why various alternatives are studied in laboratories. Another hollow tubular structure, BCN (Boron Carbon Nitride nanotubes) shows promise because of its possibility for tuning nanostructures electrical properties by B/N concentration variation. But tube diameter and helicity are currently difficult to control and so manufacturing problems still exist. Scientists from NIST (National Institute of Standards and Technology) and Turkey’s Bilkent University predict that a well-known, inexpensive molecule: Ethylene could become the future of H2 storage. Their calculations show that titanium atoms attached to an ethylene molecule can drastically increase H2 storage to reach 14 percent of the weight of the titanium-ethylene complex (Durgun et al., 2006). As the U.S. Department of Energy specified that about 7-10 percent by weight storage should be sufficient for commercial viability for both ground and space transportation applications titanium ethylene can be an easy inexpensive solution for H2 storage.

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4.4.4. Batteries Space power systems used high performance batteries such as lithium ion or nickel metal hydride accumulators for powering devices. Nickel hydrogen or nickel metal hydride batteries are essentially used in small sized elements like for extra vehicular activity (EVA) suit devices and experiments. That is why powerful and miniaturized batteries are needed to improve portative tools autonomy. Ultracaps (kind of battery where electric energy is directly stored as positive or negative charge without any reaction on the electrode surfaces) with mechanical storage with kinetic wheel are also developed for pulsed and power driven applications and are planned for Space or Lunar station. The lifetime and efficiency of charging and discharging cycles in these batteries is critically dependent on storage and/or intercalation properties of the anode material. Nanostructured materials offer improvements power density and durability by controlling the charge diffusion and the oxidation state on a nanoscale level (Khullar et al., 2004 cited in VDI, 2003). Carbon nanotubes and fullerenes therefore provide an alternative to current anode fabrication technology with graphitic carbon. Cathode material can be built with carbon aerogels, carbon nanotubes, vanadium oxide or LiCoO2-particles and anode with Sn/Sb oxides. Carbon nanotube anodic layers around metal cathodes, such as Cu, are currently investigated as well as Li and K intercalation in single-wall carbon nanotube bundles and/or multiwall nanotubes. Other experiments report increasing energy density with MnO2 or poly (o-anisidine) (POAS), a polyaniline derivative, with nanomaterials TiO2 as cathode. A significant improvement in both the current Ni/H and Li/C battery technologies with respect to the current storing capacity and discharging efficiency is expected. In lithium ion batteries, nanoparticles of cobalt nickel and ferric oxides in the electrode material (Poizot et al., 2000) can increase reversible charge capacity by 600%. The increasing miniaturization of electronic components requires flexible batteries that can be integrated into circuits. Thin film batteries (in particular Li ion batteries), whose dimensions and power density can be adapted to the respective chip components, offer numerous advantages for space applications. (VDI, 2003)

4.4.5 Energy conclusion Various types of energy generation and storage already exist. Nanotechnologies have the potential to improve their achievements, reducing their size and so their costs. Those applications are explored for both ground and space sectors but space research is more focused on

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those topics because energy is a key point for future spacecraft according to the increasing need of autonomy. The following table summarize the different nano applications for energy in space under study:

Technology Characteristic Interest Perspective Nanoparticles into propellants

Improve their efficiency, decrease volume needed

++ Short term

Quantum Dots reinforcing solar cells

Improve energy conversion rate +++ Middle term

Nanoparticles for fuel cells electrolytes

Improve fuel cells efficiency ++

Short term

Nanotubes for H2 storage (essentially Carbon nanotubes) for fuel cells

Improve H2 storage rate and in the case of carbon nanotubes is radiations resistant

+++ Middle term

Nanoelement for battery Improve existing battery efficiency

+ Short-Middle term*

*Notice: It depends of the nanoelement used, carbon nanotubes integration is more a middle term vision because of the difficulties for its manufacturing.

4.5. Life support Life support is becoming a key research axis in space sciences. With the development of longer manned mission and space tourism, monitoring the life on the International Space Station or in shuttles is a real challenge. There are numerous applications of nanotechnology within life support. The important life support tasks have been summarised by VDI as oxygen supply, pressure monitoring, ventilation, heat absorption and rejection, waste water treatment, monitoring of water quality, CO2 removal, hygiene, air cleaning and filtration, control of air quality and humidity, health monitoring, filtering, avoiding moistures, decontaminating. According to NASA, nanotechnologies can find potential application in gas storage, wastewater treatment and sensors. (VDI, 2003)

4.5.1. Global life support As long travel mission for human far exploration are seriously engaged, enhancing on board life management become a necessity. Nanotechnologies can bring technological solutions to astronauts’ daily problems. Gas sensors: The electronic nose based on gas sensors is used for monitoring air quality and to detect fire warning. Nanotechnology is expected to improve the selectivity of these gas sensors. Various types of metal oxide and ceramic nanopowders can be used to improve the performance of electrochemical sensors. (VDI, 2003)

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NASA researches are focused on the topic of miniaturized sensors. Researchers from NASA’s jet propulsion laboratory developed a nanocarpet. This unique structure is a carpet of self assembling carbon nanotubes that can be used for trapping microscopic particles or micro organisms (e.g. inorganic particles, pollen, bacteria, spores). Its function is first trapping microscopic particles for scientific analysis (Noca et al., 2004). But another function of the nanocarpet can be cleansing. University of Pittsburgh researchers enhance nanocarpet to create one that not only traps particles but also kills bacteria and others pathogens. Unlike other nanotubes structures, these tubes display sensitivity to different agents by changing colour and can be trained to kill bacteria, such as E. coli, with just a jab to its cell membrane. Indeed a particular nanocarpet combines a quaternary ammonium salt group, known for its ability to disrupt cell membranes and cause cell death, with a hydrocarbon diacetylene, which can change colours when appropriately formulated. The resulting molecule would have the desired properties of both biosensor and biocide (Russell et al., 2004). Nanomix, a company devoted to the build of nanosensors, has recently demonstrated efficiency and selectivity of electronics noses base on carbon nanotubes in the frame of a SBIR phase II program (Star et al., 2006). They integrate multiple sensor elements consisting of isolated networks of single walled carbon nanotubes decorated with metal nanoparticles (for chemical selectivity). Efficiency was proved for H2, CH4, CO and H2S. Water cleaning: Pollutants and germs can be effectively removed from water using Nano-membranes. The advantage of Nano-membrane is reduced pore blockage as compared to conventional membranes. Argonide is developing nano-porous ceramic filter membranes for the sterilization of treated water in a NASA SBIR project. (VDI, 2003)

4.5.2. Medical systems With the development of deep space living flights, enhancing medical system is becoming a key point of longer manned mission. As critical risks for astronauts, the following should be mentioned among other things:

Figure 4.3 : Nanomix sensor

http://pubs.acs.org/cgi-bin/article.cgi/jpcbfk/2006/110/i42/pdf/jp064371z.pdf

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bone, muscle, performance loss, heart and blood circulation problems, distortion of the sense of balance, of the immune system, radiation damages, insufficient methods for on-board medical therapy and diagnostics (Stilwell, 2001). Another key point is the miniaturization of medical devices in order to adapt them to space transport. Substantial progress was made in this field by the conception of MEMS based medical devices. Nanotechnologies will not decrease significantly their size but can bring new functionalities that can gather various functions in a same device like with lab-on-a-chip systems. Numerous research programs of NASA focus on life sciences in co-operation with other federal institutions (e.g. NIH) or industrial partners. (VDI, 2003) They aim to apply nanotechnologies to achieving space medical systems. The main objectives include minimal invasive, efficient and mobile detection systems, methods of early diagnosis in particular of cancer, bio molecular imaging, miniaturized diagnostics and autonomous therapy. Applications of nanotechnologies can be identified in: - Miniaturized analytical devices for medical diagnostics like lab-on-a-chip-systems that allow complex analysis sequences by individual controllable micro valves and channels. UCLA has developed in partnership with NASA a lab-on-a-chip for blood testing that can allow direct on board tests (Amudson, 2006). To produce that kind of device, the most promising method is the Fountain Pen Nanolithography. A CANEUS project is currently working on the future of this technique integrating micro fluidics with nano-fabrication, thus combining both top-down and bottom-up paradigms. This technique seems to be the most promising method of large scale nanoelectronics production that will be necessary for its routine use in manned mission. - Nanoparticles use for the detection of molecules (proteins, DNA) like gold nanoparticles, semiconductor nano-crystals (quantum dots) or also magnetic nanoparticles. - Oligonucleotide biochips (e.g. for gene analysis) that allows simultaneous detection of different analytes, high speed analyses, as well as small and compact test kits. In this field NASA is developing “Ultra

sensitive Label-Free Electronic Biochips Based on Carbon Nanotube Nanoelectrode Arrays” that allow fast detection of gene mutation which is the major causes for the development of cancer and genetic diseases and also the main risk of radiation exposure. This biochip is build on a basis of multi walled carbon nanotubes array used to collect electrochemical signals associated with the target bio molecules, which are specifically bonded to the

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Figure 4.4 : NASA biochip

http://www.nasa.gov/centers/ames/research/technology-onepagers/ultrasensitive_biochip.html

molecular probes covalently attached to the end of the multi walled carbon nanotubes. The probe molecules could be designed as specific biomarkers such as nucleic acids or proteins (NASA, 2006).

-

Drug delivery realized in principle from nanoscale cage molecules (e.g. liposomes, fullerenes or other cage molecules such as dendrimers) or by coupling with nanoparticles. The most advanced devices are miniaturized testers for bio molecules and diagnostics. Applications for nanoparticles or drug delivery seem to be expected in a longer term like for ground applications. With the help of nanotechnological therapy procedures a distinct progress in the autonomous self-diagnostics and medication of astronauts is expected in the future that is an important prerequisite for the realization of long manned space missions outside of the earth orbit. During a manned Mars mission, which is considered as a long term objective both for NASA and ESA, there would be no possibility of external medical supply of the astronauts for a period of up to three years, apart from capabilities of telemedicine which will be developed until then. A CANEUS project is also under development on this topic: “Astronaut health monitoring”. This 3 years project goal is building a new generation of miniaturized biomedical devices for astronauts for 2009. The sensor-on-a-chip for human health monitoring developed in the frame of this project consists of fully integrated microelectronics, micro fluidics and bio functionalized sensors on a single chip format using Polypyrrole bio functionalized electrodes. Polypyrrole is a selective conducting polymer adapted to detect glucose, cholesterol and a host of other blood molecules as well as volatile liquids and gases for environmental sensing. NASA is also preparing in-vivo test for a nanosensor to monitor space radiation exposure (Flinn, 2005). It is a molecule size sensor, built using dendrimers, which could be placed inside the cells of astronauts to warn of health impacts from space radiation. Researchers group set out to develop biosensors for real-time monitoring of radiation-induced biologic effects in space. They sought to develop cellular biosensors based on dendrite polymers, using nanoscale polymer structures less than 20 nm in diameter as the basis for the biosensors. To make use of this nanotechnology, an astronaut would inject a clear fluid, placed with nanoparticles, into his bloodstream before a space mission. During flight, he would put a small device shaped like a hearing aid into his ear. This device would use a tiny laser to count glowing cells as they flow through capillaries in the eardrum. A wireless link would relay the data to the spaceship’s main computer for processing. This scenario is at least 5-10 years away;

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however most of the important research is being conducted in the laboratory. The researchers are trying to fix nanoparticles on lymphocytes and the answer can be induced by detection of suicides enzymes produced by the cell when it is irradiated.

4.5.3. Textile Nanotechnologies can also be developed to improve astronauts comfort and protection with textile innovations by creating space clothes more efficient and more adapted to harsh space conditions. Various textile technologies are under development not only for astronauts but they can find applications in spacecraft. Sensatex, a developer of integrated smart textile systems, has announced in 2006 the beta launch of its Smart Shirt System. The system makes it possible to remotely monitor a wearer's movement, heart rate, and respiration rate in real-time through a conductive fibre grid that is seamlessly knit into the material of the fully washable shirt. Early research for the Smart Shirt System was funded by the DARPA9 and the Technical Support Working Group. This kind of device combines nanotechnologies enhancement for textile and improvement of health self monitoring. The same is possible by addition of core shell nanoparticles. They improve electrical, magnetic, optical properties and so can serve as diagnostic coating for astronauts’ suits. Others nanoparticles can be used to improve space textiles functions like silver nanoparticles that can provide antibacterial and anti fungal functions (nanoroadSME, 2006). Other developed products like Nano-Tex Coolest Comfort fabric or klimeo fabric can be used for space applications because of the new properties they provide: prevent moisture apparition, regulate internal temperature according to the external one. It appears more like comfort applications for astronauts but can become a critical point in the case of long manned mission.

4.5.4 Life support conclusion As enhancement of life management in space is a key topic of the future years, several space studies are focused on it. They take advantage of the electronics and medical researches achievements and fit them for space applications. That is why the most advanced devices for life management containing nanotechnologies are sensors for gas detection or other medical applications. The following table summarize the different nano applications for life management in space under study: 9 US Defense Advanced Research Projects Agency

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Technology Characteristic Interest Perspective Nanocarpet Particles detection, space

radiation resistant +++ Short term

Carbon nanotubes in gas sensors

Improve their sensibility; harsh space conditions resistant

+++ Short term

Carbon nanotubes in Lab on a chip / Biochip

Improve their sensibility; harsh space conditions resistant

+++

Short term

Drug delivery Enhance health management +++ Middle term Smart textile More adapted to space conditions,

health monitoring ++ Middle term

4.6. Satellites / Science payloads Satellites are very small-unmanned spacecraft, which were first designed for scientific analysis (observation / particles detection of earth, other planets, universe) and for several years have been used for commercial applications such as communication or GPS. Others functions of satellites take place in military applications but this field will not be treated. To achieve their missions, satellites are equipped by science payloads that are functional devices allowing scientific analysis, data collection and transmission. Technological needs will be different according to the function of the satellite. Scientific satellites are launched by national or international space agencies to enhance the knowledge about space. It includes various missions like earth observation; planet, universe exploration and so have various functions like observation; atmosphere, planet surface particles collect and analysis (bio, chemical or physical properties detection). In the case of non-orbital mission one speaks more about probes. The needs identified for this kind of missions are for one part development of more autonomous systems in order to increase missions’ duration and on the other hand the miniaturization of satellites to decrease their weight and so decreasing launching costs. As probes are often used for deep space exploration (e.g. asteroid belt) problems of miniaturization and autonomy are all the more important. Companies that use the potential of satellites for business have launched commercial satellites. The two main commercial applications for satellites are: communication (e.g. cell phones, TV) and GPS. The need identified for commercial applications is clearly costs reduction and for that mass and size saving. Thus the evident technological trend for satellites is miniaturization (even if there are some exceptions like in telecommunication where certain

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satellites can reach several tons). Since the launch of Sputnik in 1957 (84 kg), satellites weights have decreased to reach a ten kg for current satellites in orbit. Researches are currently focused on the nano and pico satellite development. Prefix used to qualify those satellites doesn’t express the size of the satellite itself but a class of weight (1 to 10 kg for nanosatellite, 0.1 to 1 kg for picosatellite). They most express an average range of size components. The ultimate goal of satellite miniaturization is the construction of a satellite-on-a-chip which represents the idea of a completely functional satellite built as a monolithic integrated circuit. Expected dimensions are: 216 cm² total design space, less than 5mm thick, lass than 100g mass, 100 mW peak power (Barnhart et al., 2005). In addition to the economic potential of nano/pico satellites represent, miniaturized launches can also be very useful for technological improvements and testing of new nanotechnologies. Aerospace is not a very innovative sector in the sense where space launches are very expensive and failure zero is needed. A co-founder of CANEUS, Thomas George said “technologies flying in space are 10 years behind what is state of the art terrestrially” (CANEUS, 2002). So the use of well-known technologies is safer in the same time for astronauts in the case of manned missions and for space agencies budgets. But the revolutionary potential of nano/pico satellites to make small, light and cheap satellites can change the use of emerging technologies like nanotechnologies in spacecraft. If satellites are cheaper, quantity launched can be increased at equal costs. It means that some of them can be lost without serious financial consequences. So space agencies can consider the use of their satellites not only for space mission but also for nanotechnologies testers in order to improve both their space and technological knowledge. Thus, nanotechnologies development follows a kind of virtuous spiral due to satellites potential:

Thus within the main space agencies program, industries are involved in the satellite miniaturization race which includes a part of enhancement in

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the on board nanotechnologies integration. Several examples can be quoted: The NPS CANEUS program goal is to transform satellite from a prohibitive tool to a consumer good and consider launch of a satellite including advanced nanotechnologies for 2009 in those components: Thermal management control, power management, attitude and station-keeping, communications and control, data management, autonomous navigation (in 2011), coordinated formation flying (in 2011) (Delft University of Technology and Systematic, 2005)

Target Costs for Satellite Classes Show 100x improvement! Target Costs ($ million) Satellite

Group Mass

(including fuel)

Manufacturing Launch Insurance Total Cost

Large Sat

>10,000 kg $154.0 M $100.0M $62.0 M $316 M

Nano Sat

1-10 kg $3.0M $0.2M $0.8M $4.0M

Pico Sat 0.1-1 kg $1.5M $0.1M $0.4M $2.0M

Target Costs for Satellite Classes Show 100x improvement! Target Costs ($ million) Satellite

Group Mass

(including fuel)

Manufacturing Launch Insurance Total Cost

Large Sat

>10,000 kg $154.0 M $100.0M $62.0 M $316 M

Nano Sat

1-10 kg $3.0M $0.2M $0.8M $4.0M

Pico Sat 0.1-1 kg $1.5M $0.1M $0.4M $2.0M

Figure 4.5 : CANEUS

http://www.csba.nu/activities/recap/060509/caneus.nps.pdf

NASA has several missions already including micro technologies on nano or picosatellite (e.g. OPAL mission, ST5). They are also implicated in test research program called Space Test Program (SPT) to test various new technologies directly on board satellites (e.g. TECH SAT 21). To achieve the goal of on board testing, several engineering schools build satellite programs for their students. By this way student improve their spacecraft knowledge and space agencies can take this opportunity to test their new technologies like nanotechnologies in space conditions (e.g. Delphi C3, Delft University of Technology and Systematic, 2005 and Star shine 3 Satellite10) Thus, nanotechnologies will not revolutionize the miniaturization process because MEMS technologies have already allowed significant weight reductions. On the other hand they can bring solutions for various satellites stakes:

• Improve satellites autonomy for deep space mission using technologies developed in the part dedicated to energy.

• Optimise structure and function of various payloads that will be described in this part.

10 See: http://ilrs.gsfc.nasa.gov/cgi-bin/satellite_missions/select.cgi?order=&sat_code=STA3&sat_name=Starshine-3&tab_id=general

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So satellite miniaturization has the potential to accelerate introduction of advanced nanotechnologies not only in satellites but also in all the spacecraft.

4.6.1. Satellite subsystems Satellites are divided in various subsystems; the mains are summarized here: Electrical power subsystem: As satellites are often autonomous spacecraft, electrical power subsystem is a strategic point for them. All the nanotechnologies potentialities in this field were described in the part dedicated to energy. We can note that power wires are developed by Rice University under a NASA contract. Data handling subsystem: The data handling subsystem is basically the on-board computer for the satellite, responsible for several jobs. It receives, validates, decodes and distributes commands from the ground, payloads or other subsystem. It also gathers processes and formats spacecraft housekeeping and mission data for downlink or use on board. This sub-system implies both use of advanced software and hardware. Nanotechnologies applications for electronics can contribute to the protection against space radiations but another nanotechnology application could enhance data handling performances. Even if it is a long-term application, several advances were made in the field of quantum computing. These include building two- and three-quit quantum computers capable of some simple arithmetic and data sorting. Large technical issues must still be resolved. (VDI, 2003) The main potential advantage quantum computing represent is still its potential to secure data transmission by efficient information encoding. Attitude and orbit determination / control subsystem: Attitude determination subsystem (ADCS) and orbit control subsystem (OCS) function is to keep the spacecraft pointed in a desired direction to meet mission requirement. Tools used in those subsystems (e.g. a gyroscope) have to be more efficient and secure and on the other hand have to be as light as possible. Nanotechnological developments relevant to this area include both detectors to monitor spacecraft dynamics and devices to control those dynamics. The detectors can include optical detectors (e.g. micro nanotechnologies star mappers), magnetometers (to determine attitude with respect to the geomagnetic field) and MEMS-based sensors to determine the rate of angular motion (NASA, 2001).

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Propulsion subsystem: Because non-ideal forces can make a satellite move from its trajectory, propulsion subsystem is needed to mitigate this effect. Several studies were conducted to study the feasibility of miniaturized propulsion subsystems. Today only MEMS or micro propulsion effort (this technology embeds discreet amounts of propellant in an array of sealed capsules on a silicon substrate (Barnhart et al., 2005)) were achieved but a CANEUS project is currently focused on research for low mass, high energy density storage systems and micro-nanotechnology based batteries for providing adapted solutions of miniaturized propulsion system according to the kind of space mission.

4.6.2. Science payloads Science payloads are anything that a spacecraft carries beyond what is required for its operation during flight. This includes the instruments for analysis (sensors, imaging tools) in the case of scientific mission and the communication instruments in the case of commercial satellites. Even if there are several different payloads according to their mission, three main kinds of payloads have been identified:

• Sensors • Imaging instruments • Communication systems

4.6.2.1. Sensors Sensors will use electronics technologies developed in part 2.2.2 of the present report according to their functions. They can be used to detect biological components (e.g. bacteria), chemical components (e.g. planet atmosphere composition), or physical components. Various technologies are being developed to make sensors based on nanotechnologies such as quantum dots, nanocrystals to enable wavelength-selective emission, carbon nanotubes, nanophotonic waveguide potentially suitable for interconnections needed to build “photonic chips” (Aerospace America, 2005). The geometric factor of a detector sets the number of particles it will collect and thus the instrument’s ability to count statistically significant numbers of particles. In this case sensor miniaturisation will reduce this ability and thus may compromise measurements. So the limiting factor of sensor miniaturization is to measure a critical flux and sensor size can be reduced only where it does not compromise measurements at that level (Aerospace America, 2005).

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Sensors can be used to detect energetic particles specific for space (solar protons, radiation belt electrons, auroral electrons). A nanosensor based on niobium nitride was built by a team of Delft University of Technology and Netherlands Institute for Space Research (SRON) to detect terahertz frequencies. Terahertz frequencies are contained in cosmic radiation and so can be used to have more information about the birth of star systems and planets. First tests on earth atmosphere are planned for 2008. Sensors can also be used to detect bio molecules on the principle of ground lab-on-a-chip. Researchers from NASA’s Marshall Space Flight Centre are working on the adaptation of ground lab-on-a-chip for space mission and more especially for Mars exploration. This array will be used for the identification of genes, DNA, bio molecules that can found on the Mars surface (NASA, 2004). The most advanced structure containing nanosensors is “black box” developed by NASA in collaboration with Aerospace Corporation. This black box containing nanosensors will be attached to a main spacecraft and will separate from it when it re-enters the Earth's atmosphere. Nanosensors are used to gather data such as temperature or pressure about flights vehicles re-entering earth atmosphere to validate thermal protection systems for human missions. It can improve reliability and safety of crewed vehicles and aid in planetary exploration, to help reduce the hazards of re-entering debris. The NASA black box or Re-entry Break-up Recorder (REBR) weights about 1 kilogram. A prototype test was envisaged for summer 2006 aboard an expendable Delta II rocket but as the rocket was not launched the prototype was not tested. Moreover NASA has plan to rapidly use nanosensors systematically in mission to Mars and the moon, if everything goes fine, routine use of nanosensors is planned for around 2025. Nanosensors would be packed into small spheres to be used with the Crew Exploration Vehicle (CEV), NASA's future replacement for the shuttle. This CEV will be shown in a demonstration flights by 2008 and manned flights are expected for 2014 (NASA, 2005). This black box flight, expected soon, represents a big step in nanotechnologies application for aerospace. Even if some nano applications in energy or materials are very soon available, it is considered as the real first nano object used in spacecraft.

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Figure 4.6 : REBR, the Aerospace Corporation

http://www.nasa.gov/centers/ames/multimedia/images/2005/blackbox.html

4.6.2.2. Imaging instruments Imaging instruments include cameras, spectrometers, altimeters, photometers for both visible, infrared, ultra violet, radars (to collect information of the inside of the planet). Concerning instruments themselves, no nanotechnologies applications have been identified except the possibility to introduce carbon nanotubes based electronics in instruments. For example, a carbon nanotube based X-ray diffraction spectrometer has been developed and would be ready for NASA Mars missions 2009-2010 in order to study rocks and soil. Except this future application, some imaging instruments can be used to identify space components at the nanoscale like scanning probe microscopes and secondary ion mass spectrometers that have a resolution to the nanometre.

4.6.2.3. Communication Nanotechnologies can contribute to the enhancement of data handling, communication intra satellite; inter satellite, between earth and spacecraft. Even if power data transmission will be different according to the distance to transfer and the kind of mission, technologies developed find applications in all the communication structure. A communication system is often made by an antenna to receive and/or emit data. This latter can be build with carbon nanotubes as it investigates by NASA for antenna at optical frequencies. MEMS-based phased-array antennae are also investigated. In the long-term these could prove important because

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of the critical need for real-time data downlink to support some kind of missions such as the space weather satellite (Kraft, 2005). New metamaterials for antenna arrays are also planned. Carbon nanotubes can also be used as mass saving for microwaves amplifier. Long distance transmissions are based on microwaves but traditional microwaves amplifier are heavy (1 kg). As a kilogram payload roughly costs € 15 000 on a satellite, the need of payload weight saving is a priority for satellite competitiveness. The current microwaves amplifier used in space are based on “hot cathode” technology. A team of researchers from Cambridge University showed that a “cold cathode” is possible using carbon nanotubes that can directly generates electrons at microwaves with an economy in weight and size of almost 50% (Teo et al., 2005) The communication system is made up of a transmission data system using most of the time optical data communication that include nano optoelectronics diffractive optical elements, optoelectronic transducers and photonic components. Optical satellite telecommunication can be enabled by the application of nanostructured optoelectronic components. These include e.g. quantum well or quantum dot lasers and photonic crystals. Photonic crystals are a further example of nano-optoelectronic components with application potential in optical data communication. Two-dimensional structures can be routinely manufactured with high precision. At present, intensified efforts are made for the development of three-dimensional photonic crystals. Three-dimensional photonic crystals would open up new possibilities in optical data communication (light could be guided and branched to arbitrary directions) and offer in principle the potential for the realization of purely optical circuits (optical computing). Infrared sensors offer an alternative way of making optical data communication. The infrared sensors can benefit from the use of quantum wells, quantum wires or quantum dots through miniaturisation and improved band gap selection. The centre for space microelectronics technology at NASA is developing GaAs quantum well infrared sensors (VDI, 2003). However nanoscale infrared sensors are not available as yet. Quantum technology, developed since 2000 at the NASA Glenn Research Centre could also solve the ongoing problem of how to communicate with, or otherwise extract information from, a nanoscale electromechanical systems (NEMS) device. This technology will be used in the future to develop optical communications protocols and components applicable for nanorobots. Quantum information may potentially enable a strong safe information encoding.

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Finally it is important to notice that not only traditional optical data transmission are improved by nanotechnologies but also nanotechnologies allow the building of materials with innovative properties that can play a role in data handling. As an example aerospace scientist continued to explore the use of nanoscale glass ceramic that enhances internal communication via photonics.

4.6.3 Satellites / Payloads conclusion: The most spectacular scientific improvements in the satellites and payloads topic are the progress made to build more integrated smaller devices. This topic has identified the main activities in nano and pico satellites. The following table summarize the different nano applications for satellites and science payloads in space under study:

Technology Characteristic Interest Perspective Carbon nanotubes based sensors

Sensor sensibility improvement; harsh space conditions resistance

+++ Short term

Black box using nanosensors

First nanointegrated object for space. Small device integrating several sensors resisting to harsh space conditions

+++ Very short term

(available)

Nanoelements for imaging instruments

Improve their efficiency, harsh space conditions resistant

+

Middle term

Quantum information Enhance security of information +++ Long term

4.7. Futuristic visions If in the near future applications of nanotechnology seem possible for traditional missions, their applications have a huge potential to achieve some very old human dreams. Indeed as flying was considered as science fiction two centuries ago, some space dreams that currently appear like science fiction may be achieved one day and surely with the help of nanotechnologies. To promote scientific researches for space futuristic vision like space elevator or space colonisation, NASA has an institute devoted to those questions: the NASA Institute for Advanced Concepts (NIAC11) has the mission is to promote forward-looking research on radical space technologies that will take between 10 to 40 years to come to fruition. ESA also explores what can be space future with a collaborative project called Ariadna12.

11 See: http://www.niac.usra.edu/ 12 See: http://www.esa.int/gsp/ACT/ariadna/index.htm

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4.7.1. Space elevator In the most basic description the space elevator is a 37,786 km cable that would stretch into space from a floating platform in the equatorial Pacific Ocean. Satellites or other payloads would be loaded onto climbers which would ascend the paper-thin cable by squeezing it between sets of electrically driven rollers or electromagnetic forces13 14. Even if it looks like a science fiction objective, scientists are seriously thinking of its implementation because of the big advantages it represents. The current problems space scientists encounter with traditional launching pad are:

• The huge energy consumption needed to launch a spatial object • The weight constraints that it generates • The associated risks (fire, rocket destabilization)

Thus the main advantages that a space elevator could allow are –

• The weight is not a problem anymore, therefore the number of payloads onboard is no longer restricted

• Launches are definitely cheaper

All of this could call into question the current advanced technologies because of the weight and price constraints that would be partly removed. Thus a researcher from Los Alamos National Laboratory, Bradley Edwards, has been credited with giving the most rigorous thought to the components and technical breakthroughs that would be needed to build a space elevator (Aerospace America, 2006). The main conclusions of his research are that the main components in the construction of a space elevator will be carbon nanotubes. Though the technology is not going to be ready for this application soon. There has been some promising research performed by Yuntian Theodore Zhu, who built a 4cm nanotube. The challenge remains in constructing a cable that is 37, 786 km. Another important aspect is the cable security. Some smarts materials could be used to address this security challenge. The use of nanoscale sensors could be made for detecting damage. Such smart materials do not exist but research should be further conducted on it. Another constraint is the management of the power supply to launch a satellite or a rocket with the elevator. A potential solution may be by using light sensitive cells. Laser light may be projected on gallium arsenide receptors that transform it to electrical energy providing propulsion. 13 See: http://www.isr.us/Downloads/niac_pdf/contents.html 14 See: http://science.nasa.gov/headlines/y2000/ast07sep_1.htm

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In order to address the technical barriers that scientists are facing with, the NASA organizes a design contest every year to address these space challenges. There are two parts to the challenge, the beam power and tether15. There have been other concerns voiced such as terrorist attacks, hacking risks and other environmental catastrophes it could bring. There has also been concern about sharing the costs and risks internationally.

4.7.2. Space colonisation These are exciting times for human space exploration with several countries contemplating and planning manned missions to “Moon, Mars and beyond.” Indeed, space agencies such as NASA, ESA, JAXA and the Chinese Space Agency are planning a series of robotic and manned missions that could culminate in the establishment of permanent habitats on the Moon and possibly Mars. With these ambitious goals in mind, there have been large-scale efforts to design new crew vehicles, as well as powerful boosters and habitats to facilitate interplanetary human spaceflights. Nanotechnologies can find several applications for those requirements such as facing the huge constraint of space radiation with the use of carbon nanotubes for living structures. They can be incorporated into structures, electronics to allow sustainable constructions or in inhabitants’ suits to enhance human protection and health management. But the main problem they will have to confront is the need for improved monitoring of the human body. Humans on such missions would have to confront microgravity, weak magnetic fields, ionizing radiation and other cosmic hazards. Space agencies are involved in program dedicated to enhance space life monitoring e.g., NASA invested 10M$ in 2006 in a program called “NASA’s Bioastronautics Roadmap”. The main problem will be to monitor astronauts’ health: several devices are in development as it is described in part 4 but the long term effects of radiation are very difficult to control.

But one of the projects of NIAC is the use of bio-nanotechnologies to build molecular machines / bio nano robot to create a sort of "second skin" for astronauts to wear under their spacesuits that would use bio-nanotech to sense and respond to radiation

15 See: http://exploration.nasa.gov/centennialchallenge/cc_index.html

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penetrating the suit, and to quickly seal over any cuts or punctures (NASA, 2005).

Figure 7 : Bio/Nano robot, NASA Institute for Advanced Concept

http://science.nasa.gov/headlines/y2005/27jul_nanotech.htm

However, even if those developments are expected in a quite long term, the International Space Station can already serve as a test bed for conducting research that will benefit long-range space exploration.

4.7.3. Autonomous systems The ultimate goal pursued by spacecraft researchers is the building of a complete autonomous system able to make its own analysis, store and send the data, to communicate with other systems, capable of self repairing. It can be spacecraft like satellites as well as advanced robots. Satellites Swarm To achieve autonomous goal, researches are focused on satellites systems called cluster of satellite or swarms. As the main stakes of this kind of formation are secure communication and autonomy (energy generation, storage), researches are being conducted in sparse aperture signal processing, micro propulsion, formation flying, collaborative control, spatial ionosphere effects, MEMS/NEMS and software intelligence. Launch of formation satellites has already done to test and improve those technologies:

o TechSat 21, launched in 2003 is a flight experience of three micro satellites to experimental concepts for clusters very low costs, lightweight satellites in close formation.

o Space technology 5 (ST5) consists of three 20 kg satellites that will demonstrate the feasibility of 100 or more sparsely distributed nano satellite to make spatial and environment measurements. Satellites are highly integrated with miniaturized electronics, extendable booms and antenna, subsystems for communication and attitude control, miniaturized thrusters and instrumentation.

o Orbital Express (OE) is a project sponsored by DARPA. It contains an Autonomous Transporter and Robotic Orbiter (ASTRO) which is an on orbit servicing vehicle designed for spacecraft diagnostic, repairs and restocking (CANEUS, 2002).

76 Figure 4.8 : NASA TET walker

http://gsfctechnology.gsfc.nasa.gov/Featured.html

Nanotechnologies can serve for the components quoted previously and more generally for:

• Size and weight decrease of the structure by advanced materials using nanotechnologies (part 1)

• Advanced electronics devices (part 2) • Lighter and more powerful energy system (part 3) • Advanced communication devices because with the increase of

communication between the different satellites, information safety has to be maintained (e.g. quantum information)

Nanorobotics A nanorobot could be defined as a robotic system capable of motion and steering in a complex environment, collecting surface chemical / biological samples or data, and communicating with the carrier spacecraft and the earth control station. It is the most complex of all the systems conceptualized so far, because they may include the integration of all the above technologies plus extremely well-developed motors, sensors, and steering systems to operate in extreme or rough environmental conditions. As research on component materials, devices, and applications is already in progress in laboratories, it is possible to envisage nanorobots in the quite near future. The advantage in space exploration will be to carry hundreds or thousands of such robots on each mission and to explore vast areas of a remote planet in each mission. To confirm this trend, NASA is currently working on a project called ANTS (Autonomous NanoTechnology Swarm) which is 12 tetrahedrons (a pyramid with 3 sides and a base) made of 26 struts (thin, extendable, metal rods) for Mars exploration application containing nanotechnologies like advanced nanosensors. Unlike the current wheeled rovers, it will be autonomous, so it will not require instruction from a whole team of scientists to complete a simple task. It will recognize obstacles and figure out how to get around them. It has a huge advantage over wheeled rovers because it does not require flat ground to operate properly. A robot called "TETwalker" was tested in 2005 to join the NASA swarm project. Traditional motors were replaced with Micro- and Nano-Electro-Mechanical Systems. The struts was replaced with metal tape or carbon nanotubes that not only reduce the size of the robots, but also greatly increase the number that can be packed into a rocket because tape and nanotube struts

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are fully retractable, allowing the pyramid to shrink to the point where all its nodes touch. All systems are being designed to adapt and evolve in response to the environment. These miniature TETwalkers, when joined together in "swarms," will have great advantages over current systems. The swarm has abundant flexibility so it can change its shape to accomplish highly diverse goals. This is the NASA first step to completely autonomous robots.

4.7.4 Futuristic visions conclusion Al those perspectives are in a long-term future and will may not be the most appropriate in this future. Nanotechnologies already find a lot of applications in futuristic vision because of the new technical opportunities they offer but with the enhancement of “nanoresearch” in the following years we can imagine that they will be the key for the achievement of those “science fiction” projects.

4.8 Conclusion Since 1957 and the launch of the first spacecraft, the space sector has known several technological enhancements allowing more and more scientific explorations and the development of commercial applications. Nanotechnology is an emerging field that just begin to find applications in ground devices. So it explains why nanotechnologies for space applications are more a perspective than a reality. Some nano applications can be considered as short term perspective (e.g. nanosensors) and other are more visionary (e.g. molecular electronics). But what is sure is that space agencies, and companies are engaged in the development of nano applications for spacecraft because they are convinced that those emerging technologies have the potential to:

• Help them to face space constraints, reducing costs • Allow serious technological improvements necessary for the

development of novel space missions (manned mission to Mars) • Create breakthroughs that can revolutionize space sector by making

it more innovative than it is currently by the possibility to test new technologies in space conditions and by reaching futuristic visions like the space elevator.

So to summarize potential nano applications in the space sector in a chronological vision, the following scheme shows several applications developed in space laboratory according to their potential time to market. It is important to note that most of those applications are middle or long-

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term vision and so are dependants of the technological improvements in all the sectors concerned by nanotechnologies. Another key aspect will be the priority that will be given by space agencies to those technological improvements. Nanotechnologies have the potential to enhance spacecraft, improving space knowledge and have also the potential to be improved by the space sector. But nanotechnology development is a long process and in some cases priority can be given to the development of new space missions integrating well-known technologies to the detriment of a focus on new technologies. This choice is more strategic than scientific and is available for both sciences and commercial applications. Summary of the main nanotechnologies applications for spacecraft according to their time to market

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Short term

0-5 years

Middle term

5-10 years

Long term

10-15 years

SpaceSystems

Space sub-systems

Spacedevices

Nanoparticles reinforcing polymers

Nanoparticles reinforcing composites

CNT reinforcing composites

CNT reinforcing coatings

Smart materials

CNT in transistors

CNT based memory

Bio memory

MRAMNanoparticles in

propellants

Smart textile

Battery using nanoelements

Fuel cells using nanoelements

Quantum Dots solar cells

CNT based electronics noses

Black box using nanosensors

CNT based lab on a chip / biochip

Drug delivery

CNT based imaging instruments

Quantum devices for information management

Nano/pico satellites Satellite on a chip

Autonomous satellites swarm

Autonomous nanorobots swarm

Space colonization

Space elevator

Short term

0-5 years

Middle term

5-10 years

Long term

10-15 years

SpaceSystems

Space sub-systems

Spacedevices

Nanoparticles reinforcing polymers

Nanoparticles reinforcing composites

CNT reinforcing composites

CNT reinforcing coatings

Smart materials

CNT in transistors

CNT based memory

Bio memory

MRAMNanoparticles in

propellants

Smart textile

Battery using nanoelements

Fuel cells using nanoelements

Quantum Dots solar cells

CNT based electronics noses

Black box using nanosensors

CNT based lab on a chip / biochip

Drug delivery

CNT based imaging instruments

Quantum devices for information management

Nano/pico satellites Satellite on a chip

Autonomous satellites swarm

Autonomous nanorobots swarm

Space colonization

Space elevator

Legend:

Materials

Electronics

Energy

Living suport

Science payloads

Futuristic vision

Materials

Electronics

Energy

Living suport

Science payloads

Futuristic vision This figure is inspired by VDI Technology Centre report “Applications of Nanotechnology in Space Developments and Systems”. It summarizes the main nanotechnologies applications for spacecraft on a time to market scale. This summary is only conclusions of what was said in this report and under the only valuation of the author.

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Chapter 5: Summary of Needs in Aerospace Research

5.1 Aeronautics Aeronautics is a thriving sector in Europe with two million people employed in manufacturing, operations and airports. The Advisory council for aeronautical research in Europe has set a strategic agenda for research that addresses important issues such as environmental pollution, safety, security, quality and affordability, and an efficient air traffic management system. The need in aeronautics research objectives has changed from a generation ago from being higher, further and faster to aircraft that are more affordable to travel in, safer and cleaner for the environment and quieter for residents around airfields. The creation of a new framework that assist organisations to work more effectively in achieving industrial priorities is one of the goals for supporting the growth of the industry. New standards of quality and effectiveness have been identified as goals to accomplish in order to make European aerospace more competitive. The maximum value from funds has been envisaged by facilitation of a European national and private research programs. The educational policies should be framed to ensure adequate scientists, engineers and other skill sets are available for the aeronautics sector (ACARE4Europe, 2004-1). Figure 5.1: Goals for European Aeronautics set by the Advisory Council for aeronautical research in Europe

Goals for European Aeronautics

Safety - Five fold reduction in average accident

rate for global operators - Reducing impact of human error - Higher standard of training for aircraft

operators, maintenance and air traffic operations

Quality and Affordability - Reducing Travel Charges - Increasing passenger choice - Transforming Air Freight Services - Creation of a competitive supply

chain that reduces time to market by half

Environment - Reduction in fuel consumption and

CO2 emissions by 50% - Reduction in perceived noise by 50% - Reduction in NOx emission by 80% - Reduction in environmental impact of

the manufacture, maintenance and disposal of aircraft and related products.

Air Transport Efficiency - Enabling the Air Transport system to

accommodate 3 times more aircraft movement by 2020 compared with 2000

- Reduction in time spent by short haul passenger to 15 minutes and long haul to 30 minutes

- Enabling 99% flights to arrive and depart within 15 minutes of departure time in all weather conditions.

Security - Zero successful hijacks

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5.1.2 Airframes Nanoscience and Nanotechnology provide a new method for solving old problems. New solutions can be harnessed from the disruptive technology for application in the aeronautics sector. Nanotechnology could prove effective in dealing with unsteady aerodynamics problem such as drag reduction using electromagnetic technologies. Morphing airframes have been regarded as emerging technology for aircraft providing a structure that would also reduce drag and vibration control thereby improving aircraft performance (University of Bristol). Research is needed in alternative lift mechanisms to derive lift by design of novel aero- structures using nanomaterials. Plasma generating arcs reduce the turbulence in engines thereby reducing the noise generated by aircraft.5 Another technology assisting the development of ultra green air transport system is the high-lift engine airframe. The solutions in aero structures are expected to bring benefits for green air transportation by using lightweight materials and processes for the airframe (ACARE4Europe, 2004-2). Nanotechnology surface application research would lead to friction reduction thereby reducing the environmental impact. Research in nanomaterials such as carbon nanotube composites for weight reduction and reduced fuel consumption is also expected to make air transport highly cost efficient. Low environmental impact materials and manufacturing techniques for the airframe, engine and other equipment is expected to reduce the environmental impact. Research in the use of non-toxic material with enhanced functionality such as non-inflammability is would also contribute to the environmental objective. Composite materials such as Metal RubberTM are reported to be non-toxic with applications in aircraft structures (Nanosonic, 2004). The use of green coolant for manufacturing is another environmentally friendly measure that is being encouraged. Noise reduction using MEMS devices for active control of noise is considered important for residents living around airports. Noise shielding through developing the right configuration and acoustic panels require further development. Enhancement in acoustic measurement and testing technology has been envisaged to meet customer needs (ACARE4Europe, 2004-2).

5.1.3 Propulsion High temperature materials and coatings for compressors, combustors and turbine are considered as key to enhancing engine performance thereby reducing the environmental impact. Development is further required in ultra-high temperature alloys for aircraft engines. Silicon carbide sensors are used for monitoring aeronautical propulsion systems

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are being researched (Ohio Aerospace Institute, 2005). Lightweight architecture and materials for engine rotors and structure have also been considered an important requirement in aircraft engine design. Another key development required is the design of components with reduced thermo mechanical distortion and effective sealing for turbo machinery for an environmentally friendly air transport system. New combustion solutions are to be considered for the existing configuration that may reduce the emission produced by conventional engine. New nacelle design development is needed for air breathing propulsion that is expected to reduce the environmental impact. Thrust reverser technologies for weight reduction are also being developed as a key technology for achieving environmental objectives (ACARE4Europe, 2004-2). Alternative propulsion designs for future aircraft are being conceptualized. Utilizing new forms of energy are being considered such as solar power, nuclear energy, hydrogen from the sea, beam energy devices using laser or microwaves and ground powered energy forms. (Covered in section 5.2) The search for a novel solution leading to a more sustainable energy consumption that is affordable, practical and complimentary fossil fuel is underway.

5.1.4 Aircraft avionics, systems and equipment Enhanced airborne display development in the cockpit for routing and traffic monitoring is expected to make the transportation system highly efficient providing customers with high value addition. Research and development in warning systems such as missile attack sensors and missile defence are expected to provide enhanced security for air travel. Development in sensor integration for detection using laser, radar and infrared is expected to help achieve the security goals. Enhanced communication systems with high performance air-ground data link would improve the air traffic management and highly customer oriented air traffic system. Camera and sensor technology research based on optics, optronics, lasers for detection, data fusion and signal processing for pattern recognition would make the new aircraft ultra secure. (Covered in section 5.2) Development of smart maintenance systems for condition monitoring of airframes and structures are expected to increase the interval for servicing thereby making the air transportation systems more cost effective. Coating and improved sealing solutions need to be developed to increase the lifetime of aircraft thereby making them more cost effective and environmentally friendly. Increase re-uses of systems, components and new repair methods have been identified to make aircraft more cost effective. New materials should be considered for a maintenance free

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system that is expected to drive down costs significantly (ACARE4Europe, 2004-2). Emerging technologies such as application of fuel cells for on board electrical energy generation during cruise and on ground should be developed further for implementation achieving cost efficient and environmental goals. In order to accomplish environmental goals the development of oil free systems and replacement of polluting hydraulic fluid with more electrical technologies (for e.g. braking system) in hydraulic power generation should be under further consideration. Development of enhanced fire protection system by use of fire retardant material is considered as an important goal in achieving an ultra secure transport system (ACARE4Europe, 2004-2).

5.1.5 Environment The impact of carbon dioxide and Nox emissions from the aircraft has added significantly to the greenhouse gas effect. In addition particulate emissions such as water vapour and soot have also added to the impact that affects the physical and chemical properties of the atmosphere. The change in the atmospheric chemistry is complex and not understood very well. Strategies for combating climate change have been suggested such as combining routes of large aircraft, lower cruise speed, encouraging short haul flights, reducing taxi time and eliminating circling. Further research in the new low drag wing-body blended aircraft design is expected reduce carbon dioxide emissions by 50%.

Goal Research Challenge Environment

Drag reduction through conventional and novel shapes Fuel additives Noise reduction New Propulsion concepts Emission reduction Environmentally friendly production, maintenance and disposal Better aircraft/engine integration

Table 5.1: Relating environmental goals and research challenges

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Research in other strategies such as reduction in emission by reducing fuel burning has been proposed by aerodynamic improvements, weight reduction and efficient engine. Development of laminar flow design is needed for aerodynamics though innovation is required to reduce the complexity. Development of designs in more adaptive structures would reduce the need for additional control surfaces, engines with reduced complexity and weight thereby reducing the fuel consumption. Nox control remains a main problem that is not addressed even by reducing carbon dioxide emissions by improving thermal efficiencies. The Nox emissions are dependent on the take off weight and range of the aircraft. New combustion technology and injection systems should be developed to achieve an 80% reduction in Nox. Research in lean combustion should be considered in order to meet the goals. Alternative fuels such as liquid hydrogen, bio fuels, synthetic fuels and liquefied natural gas are should be considered for further development (ACARE4Europe, 2004-2). Noise produced by aircraft is another problem that is being addressed by better design of aircraft. Research in low noise component design, landing gear faring and acoustic panels should be further developed. New engine designs such as the ultra high by pass ratio, geared fan and contra fan have been developed to reduce noise but complete elimination cannot be achieved without a radically new design. Micro-nanotechnologies are expected to provide novel concepts to reduce the noise in the aircraft. The environmental impact is reduced by design of vehicles that take into consideration all factors from manufacturing to the end of the life cycle disposal. The need for measuring techniques for boundary layer, acoustic measurement under cryogenic condition and combustion are required for improved aircraft design.

5.1.6 Safety and Security Post 9/11 the security of the aircraft and passengers is considered of paramount importance. The use of biometric controls for pilot identification, development of non-lethal devices for terrorist neutralization, enhanced video monitoring of passengers are some measure to be further considered. Protection against electromagnetic threats and secure communication data link are essential for the aircraft. Automatic collision detection and deviation from flight plan are important technology solutions to be considered and implemented. Protection against missile attacks on passenger aircraft should be developed, using heat signature reduction while providing detection and jamming facilities. Development of on-board explosive detection systems equipped with high sensitivity sensors and alarm systems, are expected to deliver higher standards of security for aircraft (ACARE4Europe, 2004-2).

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Goal Research Challenge

Safety

Flight hazard protection Advanced avionics Probability and risk analysis Computational methods Human error checking systems

Table 5.2: Relating Goal and Research Challenge for Safety and Security

5.1.7 Quality and affordability Improving the quality of the flying and the flight experience has been an important driver. The research challenges that relate to the quality and affordability have been stated in the table 5.3 below. Strategic Goal Research Challenge

Quality and Affordability

Permanent trend Monitoring Flexible cabin Environments Passenger services Anticipatory maintenance Systems Integrated avionics Air Transport management related airborne Systems Novel materials and structural concepts Lead-time reductions Integrated design manufacturing and maintenance systems Advanced design methods System validation through modelling and simulation Concurrent engineering

Table 5.3: Research needs from Strategic Quality and Affordability goals translating to research challenges

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5.1.8 European Air Transport System Europe is aiming to integrate the air transport system by improving management of air transportation. The table below gives the overview of some of the associated research challenges in Table 5.4. Strategic Goal Research Challenge

European Air Transport System

Innovative ATM operational concepts Advanced, intelligent and integrated ATM ground, airborne and space systems Rotorcraft integration in ATM systems High-density traffic systems capability in all weather conditions Airport capacity and advanced management Increased use of airspace capacity

Table 5.4: Relating European Air Transport System relation with Research Challenges

5.1.9 Future concepts for Guidance & Control Enhanced avionics and automation have been envisaged for future aircraft where computers manage the entire flight from landing to takeoff. Enhancement in the computing power with the application of nanotechnology to transistors is expected to greatly enhance centralized and dispersed operations. Improvements in computing power are also expected to bring benefits to robotics leading to the development of independent robots controlling specific tasks.

5.1.10 Current Research The research can be broadly divided into 5 themes in the nanotechnology sector: structure and materials, application needs and requirements, systems and sub systems, reliability and packaging, missions and collaborations.

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a. Structures and Materials Carbon nanotubes are one of the most important nanomaterials being developed for aerospace applications. Studies are being conducted in the use of carbon nanotubes for aerospace applications by University of Rome and INFN- Laboratori Nazionali de Frascati. Other research in carbon nanotube for space applications is being conducted at NASA investigating multifunctional characteristics of embedded structures with carbon nanotube yarn. University of Minnesota has been investigating layer-by-layer self-assembly of carbon nanotube patterns and interconnections. Minnesota State University has been evaluating the shear properties of polymer nanocomposites (Caneus, 2006). Damping properties and dynamics of nanoparticles for reinforced damping material are being researched by NAS of Belarus. Molecular dynamics modelling of thermal conductivity of engineering fluids and its enhancement by inclusion of nanoparticles is being studied by the National Institute of Technology. The Boeing Company is investigating the enhancement of conductivity in composite materials using nanotechnology (Caneus, 2006). b. Application needs and requirements ASRC aerospace and NASA have jointly collaborated to investigate the application of sensors in space vehicles. Airbus has investigated the requirements for airframe enhancement using nanotechnologies (Caneus, 2006). c. Systems and sub-systems There is a significant amount of work being done in MEMS for aerospace applications. MEMS based one-shot electro thermal switches for system reconfiguration is being developed by LAAS- CNRS. Monolithic silicon based micro thrusters for orbital and altitude control, are fabricated using the MEMS technology by Carlo Gavvachi Space and CNR IMM. Novel surface-micro machined micro mirrors for optical MEMS beam manipulators are being investigated by University of Toronto for aerospace applications. Kyushu University in Japan is studying the contemporary technology and applications of the MEMS rocket. The Northwestern Polytechnic University is investigating the use of MEMS in aerodynamic flow control. Politecnico di Milano has been researching MEMS integrated electro-fluid-elastic modelling for aerospace applications. Presens has been studying silicon MEMS pressure sensors for aerospace applications. Design and fabrication of Non-powered MEMS trajectory sensors are being developed by CEA, DAM and CNAM in France. The Tokyo University of Science is involved in developing application of MEMS technology to a Light wave antenna for communication in space and aeronautics. Colibrys have developed standard MEMS capacitive accelerometer for harsh

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environments. Swedish Space Corporation in collaboration with Nanospace AB is developing MEMS based components and sub-systems for space propulsion. EADS CCR is developing a MEMS sensor to design a life consumption monitoring system for electronics (Caneus, 2006). CNES is conducting research in spacecraft control and command. The EADS micropak project is developing a novel modular system for packaging integrated Microsystems for future applications. The National research council in Canada has been researching micro fibre optical sensor interrogation systems for aerospace applications. Thermo elastic damping in vibrating beam accelerometers has been studied using a finite element approach by University of Liege and ONERA. The Surrey Space centre has been researching satellite on a chip development for future distributed space missions. LAAS-CNRS has been investigating the development of optical micro resonators used for stabilisation and miniaturisation of high spectral purity microwave sources for space applications. Design and performance of quartz inertia micro sensors has been investigated by ONERA. Nanosensors for gas detection in space and ground applications are being developed by ASRC aerospace. New technologies for a space launcher telemetry system are being developed by Astrium Space Transportation. Bio Inspired micro driller for future planetary exploration is being researched by ESA and University of Surrey. The fabrication and performance testing of miniature electro thermal thrusters using microwave-excited micro plasmas has been developed by Kyoto University (Caneus, 2006). d. Packaging and reliability testing Magma Space technology is involved with developing, manufacturing and verifying micro-electro mechanical louvers. CNES and Nova MEMS are involved in hermiticity assessment of MEMS packaging –leak rate measurements based on Infrared spectroscopy. EADS is developing high temperature MEMS pressure sensors including reusable packaging for rocket engine application. EADS in collaboration with Albert Ludwig University is also developing low maintenance MEMS packaging for rotor blade integration. Design of packaged RF MEMS switching on alumina substrate is being developed by Xlim. MEMS reliability studies such as accurate measurement of beam stiffness using nanoindentation techniques.

5.1.11 Aeronautics application in other industries Novel solution developed for aerospace applications has benefited other industries as well. The example are aerodynamic design of cars, disc braking for cars and trains and anti-lock braking system, software systems for displays, composite materials, materials for artificial limbs,

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thermal imaging camera’s for rescue and police work and advanced business project management.

5.1.12 Funding and investment Aerospace and aviation is considered an important sector for Europe. The benefits from the sector are creation of 3 million jobs and 2.6% of the GDP to the individual member states. Indirect benefits through lifestyle and the way business is being done has been estimated to be 10% of the GDP. Reviewing the research needs ACARE has recommended an increase in funding by 65% over a 20-year period that is being invested currently. The investment is in accordance with the Barcelona European Council aims that would need to be met by public and private sources in a ratio of two-third private and one third public (ACARE4Europe, 2004-1). Contrasting the initiative to the American effort where 87% of the known airliners are being built. It has been estimated that public funding in US is three times that of the European Union and its member states. The annual turnover and number of people employer in US in this sector is more than twice of that by EU. Similarly the amount of US export in the aerospace sector is also known to be twice of the European Union (ACARE4Europe, 2004-1).

5.1.13 Policy The new investment in research and development programme would become successful only when organisation would conduct their research in Europe thereby retaining their bases. In addition 50,000 additional human resources would be required to fulfil the need to research goals. Measure to increase the production of research output is required as opposed to importing the research outputs.

5.1.14 Education and Training Employment in all aspects from manufacturing to air traffic control is at 3 million at the moment and set to rise to 5-7 million by 2020. A skills shortage is expected in the aerospace sector partly due to demographics and reduced attractiveness of the aerospace sector. A multi-disciplinary approach to training with excellent communication skills, open mindedness and cultural awareness is required. With the falling level of graduates taking up science and technology education, the demand for specialists with good fundamental knowledge of aerospace is set to rise. Another trend observed with graduating students is the fall in the number of students being recruited by the technology supply chain. There has

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been an alignment between courses offered at Universities and aerospace employers needs. A strong need to develop a permanent forum for dialogue between Universities and aerospace companies has also been voiced to ensure appropriateness and quality of education provided. The need for a pan European accreditation has also been beginning with a voluntary system in the aeronautical discipline has been made.

5.1.15 SME The supply chain orientation is so that large companies play a central role in integration. With the increased global competition, these companies have been presented with a choice of suppliers across the world putting the pressure on the small and medium size businesses in the supply chain. The SME business in the supply chain would need to implement global best business practices and leverage industrial alliances to become more competitive. This would require development of lean practices that improve the performance of the SME.

5.1.16 Conclusion Aeronautics and aviation is an important sector for the European industry. The identification, development and implementation of nano-scale technologies in aeronautics would increase the global competitiveness of this industry. Greater research is required in the development nanotechnologies for aeronautic applications. There is also an imminent need to increase communication between research communities in aeronautics research and nanotechnology research. The implementation of emerging technologies in aeronautics lags a decade or in some cases even more. Therefore it maybe reasonably expected that the implementation of present nanotechnology would take another 20 years after the concepts and components have been thoroughly validated for airworthiness.

5.2 Statement of needs for Research and Development in Space

5.2.1 Introduction The exploration of the vastness of space has driven the active development of space programmes in various countries. An exhaustive survey of 384 organizations in Europe, North America and Asia has revealed that 74% of research is being conducted in research institutions (illustrated in figure 1). The technological development has also spurred activity that has been beneficial for terrestrial applications as well.

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Research in the space industry is being driven by a desire to reduce the mass and volume of payload lifted into space. Reduction in the size and energy consumption of electronics on board for data processing and control systems is another important driver for research. A significant research goal is to increase the autonomy of spacecraft by improving altitude and orbit control, health monitoring and payload monitoring. Financial investment will determine the development of lightweight and energy saving satellites, rockets, and infrastructure for space stations. The need to reduce costs is further pushing commercial off the shelf technology into space applications. The development of space programmes has also driven scientific discovery such as micro gravity research and commercial applications such as satellite communication. Enhanced services such as GPS, GIS and communications are expected from these commercial satellites placed in orbit. Improved spin off products enabled by nanotechnology are also expected for terrestrial applications.

Figure 5.2: Nanotechnology Research around the world. Adapted from the presentation of Nanotechnology in future space mission by Miland Pimpprikar et al. presented at ESA- ESTEC 2003. The barriers to the implementation of nanotechnology research and development range from economics factors to the readiness of the concept. The high research and development costs associated with applications in energy, electronics and nanobiotechnology solutions may hinder development in the long-term future. The solutions developed for terrestrial applications in nanotechnology are more likely to be adapted for space in Europe as compared to the US. Other barriers to implementation of research are likely to be extreme conditions in space such as high radiation, temperature changes and high cyclic loading of structure in take off and re-entry, and the lack of communication between communities involved in space and nanotechnology research. This is expected to slow implementation of research in Europe. This summary of research needs has been compiled by reviewing the problems and challenges faced by various nanotechnology applications in

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space. The various technology solutions are at different stages such as fundamental or basic research, applied research, proof of concept and validation. Each of these research needs or concepts is considered of some strategic importance to the space objectives.

5.2.2 Nanomaterials for space craft structure Space research has been driven by the goal to reduce the lift-off mass of spacecraft, and improving safety and flexibility of space missions. Reduction of costs is also an important parameter for space missions. Nanomaterials research could contribute to the successful achievement of these goals. New research is required in light nanocomposite materials, thermal control elements, miniaturized cooling loops and heat exchangers. Carbon nanotubes (CNTs) offer a distinct advantage as lightweight materials and are regarded as one of the core materials in bringing nanotechnology benefits to space. Other properties such as changes in mechanical properties that can be detected by changes in electrical resistance make them excellent candidates for sensors (Zweck & Luther, 2003). Production issues have limited the use of CNTs in reinforced polymers. These include: development large-scale production methods (www.nanocompositech.com), uniform dispersion of CNTs in the matrix of the composite material, alignment and adhesion of carbon nanotubes in reinforced polymers (www.space.com), and production of CNTs of a uniform size and in high volume (Science Daily, 2005). The integration of nanoparticles into components such as airframes has to be researched further before the excellent mechanical and heat resistance properties of CNTs can be put to useful application. CNT yarns could be potentially used for weaving larger fibres that may have applications in electromagnetic shielding, design impact resistance space stations or astronaut suits. However further research is required to develop macroscopic components that may translate into applications (Zweck & Luther, 2003). Applications based on CNTs are expected only in the long term. Nanoparticles such as silicates (montmorillonite) and POSS (polyhedral oligomeric silsesquioxane) are also being considered for reinforcing polymers. Further research is required for the successful demonstration of their reinforcing properties. Metal matrix composites have excellent properties such as high heat resistance, strength, thermal conductivity, thermal expansion and low density. Materials such as metals reinforced with ceramic fibres such as silicium carbide, aluminium oxide and aluminium nitride are being examined for application in various airframe structures of spacecraft.

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However such materials require further research into their thermo mechanical properties before application as heat shields. Nanocrystalline metals and their alloys such as that of aluminium also offer excellent thermo mechanical properties. This is dependent on the nanostructure of the material that can be controlled using nanopowders. With further research they may replace titanium components in liquid rocket engines, as they are light and less prone to embrittlement by hydrogen (Zweck & Luther, 2003). Nanostructured ceramic composites, such as carbon fibres coated with boron nitride, act as a thermal and oxidative protection for construction material. Proof of concept studies are required in the application of these nanostructured materials as sensors, optoelectronic components and space structures. Space missions have to endure extreme conditions including dramatic temperature changes. Therefore thermal protection is a very important area. Enhanced thermal protection for spacecraft can increase re-usability of the vehicles thereby reducing costs. Ceramic fibre composites offer excellent thermal barriers for components such as nozzles and rocket combustion chambers or as heat shields used in re-entry. NASA is considering nanostructured ceramics such as silicon carbide for exceptional heat and radiation resistance properties (AZoNano, 2005). Research is needed in controlling the grain growth of ceramics during the sintering process that would improve the density and thereby the firmness of spacecraft components (Zweck & Luther, 2003). Electronic equipment in space crafts is sensitive to large variations in temperature, affecting communications, information processing and control of the space craft. Nanomaterials such as diamond-like carbon have a high thermal conductivity (4 times that of copper) and have been used for thermal monitoring in nanosatellites. Diamond-like carbon also provides corrosion resistance to oxygen over a wide range of temperatures. Further applied research is required in application of diamond- like-carbon as corrosion resistance. One of the most promising areas of research are MEMS structures where their friction, stiction and wear properties make them an excellent candidates for use in moving mechanical assemblies (Milne, 2003). Magnetic fluids are currently used as sealing and damping media, however they could be utilized for thermal protection of control systems for miniaturized electronic components or as self-lubricating bearing for micro mechanical components. Further research is required in utilizing the viscous, electrical and thermal properties of magnetic fluids for thermal control for miniature electronics.

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5.2.3 Energy Production and Storage Nanomaterials, thin films and membranes with nanometre dimensions are applicable in a range of energy generation and storage devices such as fuel cells, solar cells, super capacitors and batteries. This section will examine the technical challenges that need to be overcome before these technologies can be used in spacecraft. a. Solar cells Nanomaterials have tremendous potential for increasing the efficiency of solar cells. Areas that require research include anti-reflective coating and collectors. At present research is focused on III-V semiconductors such as gallium arsenide and indium phosphide. Basic research is required in engineering the band-gap of these solar cells so that longer wavelengths of light can be converted to electrons thereby increasing efficiency. Quantum dot solar cells have also been considered as an alternative solution. However, the optimum material combinations need further exploration for example from the III-V semiconductors or combinations of silicon/germanium, silicon/beryllium or tellurium/selenium. Organic dye-based, or Graetzel, solar cells are also the subject of much research due to a low manufacturing cost. The main disadvantage of such dye-based solar cells is the low conversion efficiency (10% maximum efficiency in experimental systems). Research on the nanoporous layer of titanium dioxide and novel dye molecules is aimed at increasing this efficiency (Institute of Nanotechnology, 2006). b. Fuel cells Fuel cells combine hydrogen (fuel) and oxygen (from air) to produce water and an electric current. Fuel cells are considered as an alternative to batteries in space applications. Nanotechnology research in this sector is focused on improving efficiencies by enhancing the performance of catalysts, membranes and hydrogen storage. Fuel cells with the exception of direct methanol fuel cells require hydrogen. Methanol is easier to store, however, direct methanol fuel cells face the problem of carbon monoxide poisoning of the catalysts, and overcoming this is the focus of much current research. Other areas that require further development include the proton exchange membrane, to enhance proton transfer and therefore efficiency. Solid oxide fuel cells operate at a much higher temperature and are more efficient; however they require ceramics that are stable at high temperatures. Current research on ceramic nanopowders such as yttrium stabilised zirconium aims to improve their ionic conductivity and thermal stability for high temperature solid oxide fuel cells.

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Hydrogen storage has been considered one of the most critical problems in the successful implementation of fuel cells. Increased research is needed to investigate the role of nanocrystalline metal hydrides such as magnesium nickel alloys for high temperature storage and lanthanum nickel alloys for low temperature storage. High absorption capacity has been reported for carbon nanotubes; however the results were not reproducible. Further research is required to have reproducible results in hydrogen storage with carbon nanotubes or alkali metal doped graphite. c. Batteries and Accumulators Lithium ion batteries and nickel metal hydride accumulators have been implemented within the power supply of space systems. The performance of these batteries can be improved further by using nanostructured materials. Materials that are being developed include carbon aerogels, carbon nanotubes, and vanadium oxide for cathodes and tin/antimony for anodes. Further research is required to produce higher power density and durability by controlled charge diffusion and oxidation state on a nanoscale level. With the increasing miniaturisation of electronics, the development of thin film batteries is seen as an important step. Thin film batteries can also be integrated with thin film solar cells. Research and development would be required in thin film deposition techniques for development of such devices. d. Capacitors Super capacitors, also known as nanocaps, are expected to increase power density significantly. The use of carbon nanotubes as electrode in nanocaps increases the surface area leading to a boost in the charge. One of the main issues is integrating super capacitors with highly dense circuitry for microchips. This implementation of this technology is expected to be another 6 – 8 years away (Space daily). Research at present is being conducted in using self-assembled electrically charged polymer layers as electrolyte. Alternative materials such as carbon aerogels are also being investigated for electrodes due to their large internal surface area, controlled pore distribution and pore diameter (Pröbstle et al, 2002). Other electrode materials that need further research are nanoscale spinel structures such as magnesium aluminates. Increasing the electrical conductivity is being investigated through the incorporation of nanoparticles of, for example, alkali metals.

5.2.4 Data Storage, Processing and Transmission Data processing and systems control are an important area for spacecraft. Nanotechnology applications can enable highly integrated avionics,

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wireless data communication and state of the art sensors. There is research being conducted at NASA for data processing and communication systems that need minimum energy. The research is also being conducted in highly integrated nanodevices to be used in miniaturized space systems. One area that has been highlighted for new research is a quantum device for applications in ultra sensitive detection, analysis and communication. a. Electronics There is a range of nanotechnology applications in electronics for spacecraft, including: amplifiers, diodes, silicon circuits, micro mechanical and micro fluidic systems. Research needs for some of these applications have been elaborated. High electron mobility transistors (HEMT) and heterojunction bipolar transistors (HBT) are nanotechnology enabled high-speed electronic components. With a high signal to noise ratio these transistors are used in microwave receivers and transmitters for radar and communication systems. Research is required in wide band gap semiconductors such as silicon carbide and gallium nitride that will form the basis of future transistors. These materials offer features such as high power density, increased operating voltage, smaller component size and higher efficiency leading to lower cooling requirements. Further development would be required in integrating of such systems into miniaturization of satellites. Tunnelling components such as the resonant tunnelling diodes (RTD) use fast quantum mechanical tunnelling. RTDs are used in high frequency oscillators, optoelectronic switches and photo detectors that have applications in digital electronics for satellite communication. The first logical circuits have been developed but more research is required in their production and processing. The problem faced in RTD production is ensuring the geometry of components on which the property depends. Research is also required into the selection of materials as silicon or silicon-germanium alloys are expected to integrate well with current silicon circuits. Several technical problems need to be solved for RTD to become more practical. Anti-static coatings made from a dispersion of carbon nanotubes in polymer matrix, are transparent and allow high electrical conductivity. They have applications in space structures and electrode material for solar cells, and are expected to be in use earlier than other applications. At the moment the focus is in providing a proof of concept and validation in spacecraft. Magnetic nanocomposite materials are made up of nanoscale magnetic crystals in an amorphous or crystalline matrix, such as that of polymer or silicates. Soft magnetic nanomaterials are used in transformers and

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inductors, whereas hard magnetic nanomaterials are used in energy storage, data storage and sensors. Such nanocomposites have the advantage of high sensitivity to changes in magnetic field and a wide operating temperature range (Wincheski & Namkung, 2000). Research and development is required using these properties in energy saving antennas, inductors, sensors and data memories for various space applications. Magneto electronic sensors and memory chips are based on the magnetic resistance effect (Magneto Resistance) that occurs in magnetic multilayer systems. Such sensors and memory chips are consist of ultra-thin layers of metals and insulators up to 1 nm thick. With further research they could be developed as sensors for measuring position, acceleration, and rotation. A problem that needs to be addressed is the limited operating temperature range for space applications. b. Optical Transmission Nanotechnology applications for optical space components include X-rays mirrors, high resolution optics, highly integrated CCD, plastic optics, and laser systems. Lateral nanostructures can be used in improving optical data communication by enhancing the performance of diffractive optical elements, optoelectronic transducers, and photonic components. Research in optoelectronics enabled by nanostructures can lead the way for diffractive optics. Further areas include quantum wells, quantum dot lasers, and photonic crystals. Research is also needed for nanostructures that can be used for applications such as optical satellite telecommunication, infrared sensors, and high resolution CCD. Improvements are also needed in optical wireless data links for inter-satellite communication. Such optical inter-satellite links have been demonstrated by ESA on the ARTEMIS mission. Quantum dots provide the freedom to cover the entire spectrum from ultraviolet to infrared and production methods are now well characterised. However for quantum dot lasers to be realized in space applications, it will require specification of the laser, integration into spacecraft sub-systems and qualification. Photonic crystals can also be used for optical data communication. Research is required in three-dimensional crystals that will open up new possibilities for optical data communication, potentially leading to purely optical circuits. However, significant basic research is required for photonic transistors before they can be put to practical use.16 Photonic crystals are expected to be used in optical satellite communication. For space applications, high precision processing is essential for components such as those used in optical satellite communication or for earth observation and astronomy. High costs of manufacturing equipment

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and low throughput rates, is a limiting factor for such applications. X-ray mirrors (composed of a thin single mirror and mirror foil with a nested design) play an important role in astronomy. Further research and development is required in the ultra precision finishing of surface figuring of coil substrates of X-ray mirrors (Zweck & Luther, 2003). c. Data Storage for spacecraft Nanotechnology enabled solutions for data storage systems under consideration are based on thermo mechanical, optical or holographic principles. The millipede memory being developed by IBM is a micro mechanical device that reads, writes and erases data using the scanning probe technique. The features of this technology are the low voltage consumption, high storage capacity (1 Terabit / sq in) with application in mobile devices and space. Basic research is being undertaken to prove the feasibility of the concept. Another area that has been highlighted for further research is the use of 3 dimensional arrays of quantum dots in optical data memory (Zweck & Luther, 2003). Ferroelectric RAM (FRAM) and Magneto electronic RAM (MRAM) are nanotechnology enabled memory chips that are non-volatile and are being considered as replacements for DRAM. MRAM uses the principle of magneto electronics and is also considered as a replacement for CMOS based memory. However, further demonstration of this is required. FRAM can retain data for over 10 years, but material fatigue is a considerable disadvantage. Though FRAMs are commercially manufactured and used in Smart Cards, further research and development is necessary if the technology is to be applied in space. The advantage over DRAM is a reduced time lag and energy dissipation. MRAM is considered better than other non-volatile memories (EEPROM, Flash and FRAM) for aerospace applications due to its low energy consumption, radiation resistance and high temperature operating range. However, it still requires validation for space applications. Silicon on insulator (SOI) and phase change memories (PC RAM) are also considered as alternatives.

5.2.5 Sensors Sensors play an essential role in monitoring the health of astronauts and control systems of the spacecraft. Sensors are used to accomplish a wide variety of functions in space. Nanomaterials are expected to enhance the functionality of these sensors. Gas sensors are used for detecting hydrogen leaks in rockets, measuring oxygen in the upper atmosphere and monitoring air quality in manned space flight. The different gas sensors used for space applications are Schottky diodes based on silicon carbide, resistive sensors based on

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polymer films and electrochemical sensors based on tin oxide. Further research is required in integrating electrochemical sensors with CMOS circuits. Research is also needed on nanopowders used as coatings on sensors for improved sensitivity and robustness. Schottky diodes are used for detecting hydrogen or hydrocarbons under extreme conditions. The absorption of gas molecules on the surface of the diode produces a change in the electrical conductivity. Research is required in validating the use of Schottky diodes and increasing the sensitivity. Space applications of sensors may have terrestrial applications, especially in the automotive industry. Sun sensors based on nanoporous silicon are expected to benefit from nanomaterials research. Research is required in decreasing quantum losses and improving quantum yields of the nanoporous silicon. Further research is also required in integrating the sun sensors into spacecraft such as satellites. Infra-red (IR) sensors are used for satellite-based observation of the earth, research of the atmosphere, astronomy, navigation and optical data communication. Research is required in improvement of sensors based on quantum wells, quantum wires and quantum dot nanostructures. Quantum well IR sensors have been developed based on gallium arsenide fabricated using molecular beam epitaxy. Research is required in realizing these sensors for long wave infrared radiation. NASA is working in collaboration with University of Michigan- Ann Harbor to develop nanosensors based on nanoparticles that will monitor the effect of radiation in space. One of the main problems faced on long flight-manned mission is that of radiation from space. Although the spacecraft shield will protect the craft, on 6 month long mission to mars the most advanced heat shield will may not be able to protect the astronauts. Therefore research is being undertaken to monitor, prevent and treat these effects (AIAA, 2005).

5.2.6 Life support systems NASA is researching bio-inspired, adaptable and self-healing systems for extended missions. Bimolecular nanotechnology is another area in which NASA is actively developing a biological-geological-chemical laboratory for life detection and science. Research is also ongoing in the area of nanoscale sensing, assessment and therapeutic delivery for medical autonomy. Nanotechnology may potentially offer solutions for supporting life functions such as oxygen and nitrogen storage, pressure monitoring, ventilation, reducing weight of heat exchangers by using nanomaterials,

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waste water treatment using regenerative membranes, monitoring of water quality by using electronic nose sensors, carbon dioxide removal, hygiene, air cleaning and filtration, control of air quality and humidity.10 Further research is required in developing nanomaterials, by conducting basic research in the above mentioned areas for space travel. Areas which will be important (particularly for the planned long duration manned spaceflights to other planets) are the development of sensors capable of measuring physiological parameters such as bone density, blood chemistry, disease or radiation load. This will also require more effective lab-on-a-chip systems where both the measuring and analysis unit are combined, and which allow the concurrent and rapid analysis of different analytes. Drug delivery, including autonomous self-medication, via several routes (such as inhalation) is another important area of research for long-duration space flights.

5.2.7 Nanomaterials and thin films for spacecraft Nanomaterials and thin films have applications in various areas of space. Nanostructured layer have applications in heat insulation of rockets. NASA research has envisaged the creation of high strength to mass ratio material that can be used for aerospace and space vehicles. Material research is also required in materials with programmable optical, thermal, mechanical and other properties. Research has also been envisaged for embedded sensing to ensure reliability and safety. Aerogels are made up of a highly porous three-dimensional network of nanoparticles such as silicates. They have a high internal surface area and low density, and have applications in electrode materials for capacitors or batteries, and thermal isolation. Although they have been used in the Mars Rover and NASA Stardust missions, they require further development to improve characteristics such as brittleness and mechanical stability (Zweck & Luther, 2003). Solid films developed at a nanoscale are important for space as friction and reducing layers. The tribological properties such as relative hardness, fatigue resistance, type and strength of chemical bonds determine the development of MEMS components. Intermediate layers such as lubricants, coverage layers, and friction partners behave differently in high vacuum space than terrestrial conditions (Zweck & Luther, 2003). Material selection for solid lubricants and mechanical protection such as chalcogenide, chalcogenide composites, carbides and nitrides as well as carbon material are taken into consideration for research. Research is needed in applications such as low friction and lubricant free bearings, coolers for liquid hydrogen and thermal control layer for nanosatellites.

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Thermal protection layers are used in the re-entry to act as heat shields and for thermally insulating the rocket engines. The heat insulating layer of rocket engines are required to be temperature stable, strain tolerant and have high adhesion strength. Research is needed in manufacturing processes such as pulse laser deposition that ensures high precision and reproducibility. Other applications where thin film technology can be usefully applied are – large telescopes, mirrors and antennas. Feasibility studies are required in visionary applications such as solar sails for interplanetary spacecraft and extremely light solar generators for solar powered satellites. Research is also need in intelligent multi-functional structures that can be used for active control.

5.2.8 Visionary Applications Visionary applications are, at most, at the basic research stage, and require several technological solutions before they can be reliably applied in space. a. Molecular Nanotechnology and electronics for space NASA is aiming to develop structures and systems that can adapt, evolve, heal and replicate in response to changes in the environment. Intelligent sensing requires research in areas that combine novel material properties such as optical, thermal and mechanical. Biomimetic material development is required to realize enhanced functionalities such as self-organization, self-healing and self-replication. An approach inspired by bottom-up nanobiotechnology may provide a novel solution. Artificial self-replicating systems are considered to be in their infancy, and it is essential that they are developed with rigorous fail-safes to ensure safe application. For example, a bio-inspired approach based on viruses and bacteria could pose a hazard to human health. One of the main challenges for the bio-inspired approach is the extreme environment of space where there are high temperatures, high radiation, vacuum and high pressures. Organic molecules such as benzene have potential in future nanoelectronic circuits, as they can act as building blocks. However, robust, molecular connections are among the main problems to be solved before molecular computing at femto second can become a reality. Problems in synthesizing such molecules have also been reported. Finally, further research is required to improve the level of current obtained from molecular electronic devices (Globus, 1999).

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b. Space Elevator The Space Elevator is a novel concept that has been proposed to transport mass into space from the earth using a cable or ribbon. However, such a system would require research and development of an extremely high strength-to-weight ratio material. Carbon nanotubes have been proposed as a suitable material as they has the right strength to weight ratio.12 The desired strength for a space elevator is 62 GPa with carbon nanotubes having a stiffness (Youngs modulus = 1 TPa and tensile strength = 200 GPa). Research is further required in spinning of composite fibres (carbon nanotube reinforced) that will be able to stand the extreme stresses of the earths atmosphere, turbulence in weather, corrosion, and vibrations created by the flowing winds. Among other solutions needed are tether technology for the cable, a suitable propulsion technique (potentially electromagnetic propulsion), and development of supporting infrastructure before this concept can be turned into reality (NASA, 2000).

c. Nano and Pico satellites Constellations and swarms of miniaturized satellites and probes have been envisaged such as the nanosatellite (1- 10 kg), picosatellite (0.1- 1 kg) and the satellite on a chip (less than 100g) concept. The increased integration of nanotechnology is expected to lead towards satellite on a chip. Nanotechnology can play an important role in reducing the weight, size and power consumption of smaller satellites. Micromachined devices can provide improved integration in propulsion, communication, navigation and energy generation. Research is required in areas such as high strength nanocomposite plastics and biomimetic structures to reduce weight. Further development is required of smart components with built in sensing capabilities and load monitoring. Research has to be achieved in adaptive structures with skins for improved thermal control. There is also a need for improved propellants such as those based on nano-dispersed aluminium. One of the main research challenges for the constellation of nanosatellites is the information systems that will require very high processing speeds and nanoelectronics may be able to provide solutions. Monitoring the health and safety of the constellation has been regarded as another major challenge for such nanosatellite systems, and here nanosensors can play a very important role (Johnson et al, 1999). Nanotechnologies that have potential application in nanosatellites but require further integration studies are sensors (magnetic, infrared and solar) based on optical fibres or MEMS, and the development of dedicated integrated circuits for communication systems (Torres et al, 1996). For picosatellites technical breakthrough is required in areas such as micro-fuel cells, micro-thrusters and nuclear-batteries (Simonis & Schilthuizen, 2006).

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d. Gossamer Spacecraft Gossamer Spacecraft have been envisaged to be very large, light and self-unfolding with integrated subsystems. The development of such a light and foldable structure requires an airframe inspired by nature and an energy generation system such as those based on thin film solar cells. Alternative fuel-less propulsion research needs be conducted in laser and microwave propelled sails, such as that by NASA JPL (2000). Research would also be required in thin film technology that can be used to develop phased array antennas for communication, and in integrating other equipment such as telescopes and mirrors for detecting planets outside the solar system on unmanned missions (Zweck & Luther, 2003).

e. Space Solar Power NASA and several academic institutions in the United States are considering the development of a concept called “Space Solar Power” to mitigate greenhouse gas emissions. The programme envisages the deployment of large space solar power satellites in geosynchronous orbits to potentially delivering 10-100 TW of energy to world markets. Energy would be transferred by means of high power density microwave. To realise this vision would require intensive research in multi-band gap solar cells with high efficiency and low cost of production, and development of solid state devices for wireless power transmission. Among other problems that need to be solved are the development of optical concentrators, radiation resistance thin film material, and the multi-functional integration of sub-systems (Mankins, 2003). Such concepts are also beginning to be considered in Europe and Japan. The high prohibitive cost of space transportation, however, is a major barrier. The time frame of implementation of this concept is estimated to be more than 25 years (Zweck & Luther, 2003).

5.2.9 Conclusion The research and development of nanotechnology applications has to be based on the level of technology readiness and contribution to space objectives. Other important criteria for assessing deployment are the market potential for terrestrial applications, economic benefits of the application and the potential barriers to the development. Considering the high cost of the development of nanotechnology, the programmes must be based on the economic value of the application to the space industry. This is due to the fact that future applications in space are expected to be high volume markets, as opposed to the current niche markets driven by telecommunication and information services. Utilizing space infrastructure for research and development is becoming an important issue. NASA is encouraging the participation of private companies to conduct their research through their financial investment in space. Increasing dialogue

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between space and nanotechnology research communities is essential for the continued development of nanotechnology applications for space. In any event, such research and development is expected to take nearly a decade before it is implemented in space crafts.

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Chapter 6: Economic Aspects

6.1 Introduction This chapter describes the economic impacts that the aerospace industry has in the EU in particular, but also, because of its nature, globally. It discusses the impacts on civilian aviation and space exploration, and the strategies that are being developed by the various sectors to ensure economic success, and the role that SMEs will play in this. It concludes with a presentation of patents utilising nanotechnology that are applied to the aerospace industry. The European Commission (EC) has recognised the central importance of the aerospace industry to innovation, prosperity and security, and in 2002 published a Strategic Aerospace Review for the 21st Century (STAR 21), the result of the efforts of an advisory group with members from industry, the EC and the EU parliament. The STAR 21 report recommends four governing principles for Europe’s aerospace industry:

1. Aerospace is vital to meeting Europe’s objectives for economic growth, security and quality of life. It is directly associated with, and influenced by a broad range of European policies such as trade, transport, environment and security and defence.

2. A strong, globally competitive industrial base is essential to provide the necessary choices and options for Europe in its decisions as regards its presence and influence on the world stage.

3. European aerospace must maintain a strong competitive position if it is to play a full role as an industrial partner in the global aerospace marketplace.

4. Europe must remain at the forefront of key technologies if it is to have an innovative and competitive aerospace industry.

To ensure that the aerospace industry in the EU continues to succeed, the report highlights the need for evaluating and harmonising competition policies and tax incentives amongst member states, ensuring that adequate training schemes are established (that also take account of continued education and training), that worker mobility between Member States is supported, and that long-term R&D goals are well defined. To achieve these goals it recommends that combined public and private funding for civil aeronautics in the EU should reach a total of €100 billion by 2020.

6.2 Aviation The aerospace industry is a significant contributor to economic wealth worldwide. According to the Advisory Council for Aeronautics Research in Europe (ACARE, 2004-1) the European air transport industry directly

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contributed €220 billion to European GDP (or 2.6%) in 2004, and taking into account ancillary business, an estimated 10% of GDP. Air transport alone is estimated to account for approximately 18% of all international trade. Furthermore, it is estimated that total employment within the industry in Europe is some 3 million, and that this will increase to 5 to 7 million by 2020. In the US, the aerospace industry generated $170 billion (€133 billion) in sales during 2005, with profits of $11 billion (€8.6 billion). (Napier, 2006) The major manufacturers in the industry are Airbus in the EU and Boeing in the US, with Airbus commanding slightly over half of the global market share. The most important sites for the global civil aerospace industry are Seattle (Boeing), Toulouse and Hamburg (both Airbus). However, other important global players are located in Russia, Brazil, Canada, and Ukraine: Russia There are 6 manufacturers of civilian aircraft in Russia. As of April 2007 these are to be merged into one company by the Russian government. The new company, United Aircraft Building Corporation (UABC), is being established in an effort to streamline operations and improve the Russian aviation industry’s global competitiveness (Russian Minister, 2006). The 6 individual companies are:

• Sukhoi- the largest Russian aircraft manufacturer (both military and civil) with a reported 14% of global output of aircraft products (25% for military aircraft). Civil aircraft orders are of the order of €780 million per annum (www.sukhoi.org/en).

• Irkut- primarily a military aircraft manufacturer, but with plans to increase its percentage of civilian aircraft manufacturing from 13% to 45% over the next 10 years. It had sales of €468 million in 2004 (www.irkut.com/en).

• Ilyushin- manufactures both military and civil aircraft (www.ilyushin.org/eng).

• Tupolev OKB- oldest Russian aeronautics company. Manufactures both military and civil aircraft (www.tupolev.ru/English).

• A.S. Yakovlev- primarily involved in military aircraft design, but with several small to medium size civilian aircraft (www.yak.ru/ENG).

• Mikuyan- manufacturer of the famous MiG fighter planes, but also produces small civil aircraft (www.migavia.ru/eng).

Brazil The Brazilian company Embraer manufactures small to medium sized passenger aircraft that are used by a number of global airlines. In 2005 it had revenues of 3.68 billion USD (€2.87 billion). It has over 17,000 employees (www.embraer.com/english/content/home).

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Canada Bombardier Aerospace manufactures 3 families of small civilian jet aircraft- Learjet, Challenger, and Global. It has a global workforce of 26,800 and profits in 2005 of 8.1 billion USD (€6.3 billion) (www.bombardier.com). Ukraine Antonov ASTC originally designed military aircraft for the former Soviet Union (and famously the largest aircraft ever built: the An-225 Mriya transport). However, since 1992 it has also manufactured small to medium sized civilian aircraft (www.antonov.com/index.html).

6.2.1 Global markets in the aviation industry According to the Airbus “Global Market Forecast 2004-2023” world passenger traffic is expected to increase by 5.3% per annum over the period 2004-2023. This increase in demand, combined with the need to renew older aircraft, will require an estimated 16,601 new passenger aircraft. Airbus forecasts that the number of passenger aircraft in service will double from a fleet of 10,838 in 2003 to 21,759 in 2023. In monetary terms this equates to some 1.9 trillion USD (€1.48 trillion). The market share on a regional basis looks quite different, with Europe expected to have the largest demand in terms of aircraft numbers, while operators in the Asia-Pacific will focus more on large capacity aircraft (such as the Airbus A380) and so will have the greater share of seat capacity. Typical maximum life-spans for aircraft range from 37 years for small jets to 35 years for others. In many cases large passenger aircraft are “recycled” as cargo aircraft before this point. Airbus forecasts that only 15% of today’s passenger aircraft will still be in service with their current operators in 2023. This buoyant mood is also felt by airlines within the EU. Despite staggering net losses in the US market over the last 6 years (13 billion USD in 2001, falling to an estimated 1.7 billion USD in 2006), EU airlines have seen net profits of between 1 and 2 billion USD in the same period (IATA). Although this loss in the US market is largely a result of decreased passenger numbers in wake of September the 11th, one of the other key issues is the relative cost of fuel to the airlines, contributing 26% to operating costs in 2005 (compared with 14% in 2003). Over the next 17 years Europe is expected to retain its share of the market at 32%, while the US is expected to fall from 33% to 26% and Asia-Pacific increase from 25% to 31%. Air cargo is also expected to expand over the next 17 years at a rate of 5.9% per annum. At present approximately 40% of exports by weight from Asia to North America and Europe are delivered by air, however in product value terms this is almost 75%. By 2023 it is expected that air

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cargo from Asia to North America will be greater than Europe to North America. One issue now is that packaging of such high-value goods takes up relatively more of the cargo space, such that there is greater demand for larger capacity aircraft.

What are the strategies that the industry sees as necessary to ensure continued growth? Both efficiency and capacity increases are required. The industry metric is revenue passenger kilometre (RPK), and it is estimated that increased productivity across the industry will contribute approximately 0.8% of the yearly growth in RPKs. The remainder will be met by increasing passenger numbers through more aircraft, larger aircraft, and increasing the frequency of flights. Routes- there are two airline strategies in place for connecting destinations: hub and point-to-point. Of the two, hub-based flight patterns are the most economical and long-lived. This essentially means linking major destinations together by larger aircraft, with passengers connecting via these and flying on to their final destination by smaller regional aircraft. In contrast, point-to-point flights link secondary or tertiary cities, and offer greater convenience to passengers. The success rates speak volumes: of 75 routes opened during the past twenty years between a primary city in Asia and a primary city in Europe, almost 90% have proved successful and are still in operation today. Conversely, of the 47 routes opened between secondary or tertiary cities, only 40% have been lucrative enough to survive. Within different regions the preponderance of the two types of strategy varies, with Europe favouring point-to-point, intra-regional flights while Asia-Pacific has a larger demand for hub flights. The future forecasts for world population growth indicate that by 2020 16 cities worldwide will have more than 20 million inhabitants (compared with 5 today). 10 of these cities will be in the Asia-Pacific region, which will further increase the demand for hub flights and underlines the need for larger aircraft to service this region. Passengers- it has been determined from several independent surveys that the most important issue to passengers is price rather than convenience (as evidenced by the growth of low-cost airlines). This favours hub based routing for the major airlines. Aircraft size- there needs to be continued development of different aircraft sizes: large aircraft for hub-based flights, smaller versatile aircraft for point-to-point. It has been estimated that two-thirds of new aircraft will be single aisle with between 100 and 210 seats (the size favoured by the low cost airlines). Regulation- new regulations on greenhouse gas emissions will have a major impact on the air traffic industry. As part of its strategy, ACARE has set goals of reducing fuel consumption and CO2 emissions by 50%, reducing NOx emissions by 80% and decreasing noise pollution by 50%. Air Traffic Management- improving the air traffic management systems will allow shorter flight times (as a result of less time in holding patterns on approach to airports) and less time spent taxiing or on stand. As a result aircraft turnaround will be faster and passenger capacity will increase.

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Investment in R&D- the industry already has significant investment in R&D (approximately 12% of turnover); however ACARE has recommended that 65% more funding is required over the period to 2023 to ensure that the projected growth in the industry is maintained. In contrast to other sectors, the funding available in the EU from the private sector is comparable to that in the US, while it is the public finance in aerospace R&D that is lacking (25% that in the US). However, it is not only financial investment that is required. There are issues in attracting sufficient researchers, engineers and technologists into the industry, and policy changes that will ensure that European companies retain their presence within Europe and do not migrate to North America. To ensure that this is achieved will require coordinated efforts by each member state and not just the centralised EU administration. ACARE has proposed a strategic research agenda (SRA) to meet these goals:

• As with many technical sectors the aerospace industry is facing a shortage of suitably qualified and experienced personnel. To reverse this trend there needs to be continual assessment of university curricula (aligning it more with the needs of the industry), ensuring that standards are met and improving the mobility of graduates. This will also require the enthusing of young people to embark on a career in science, technology or engineering, and strengthening links between the aerospace industry and higher education.

• Recognition that the industry also depends on the expertise and service from tens of thousands of smaller, specialist companies. What is lacking is a coherent map of these companies and their expertise, and the means to coordinate their activities and those of the larger players. In this regard there is also the need for the large organisations in particular to move away from the “perpetuation of self-interest”, and that companies must cooperate to maximise the outcomes of the limited pool of finance and expertise within the EU to achieve R&D goals.

• Policy changes at the European level that will improve European research infrastructure, the supply chain, certification and qualification, education and improving trans-European research. In addition, it will be essential that new policies encourage business to retain their centre of operations within the EU, and thus continue to re-invest in the EU R&D market. This could be through “low corporation tax rates, R&D tax credits, export credit guarantee schemes, risk-sharing equity funds, and the level and quality of publicly funded research.”

• Improved collaboration both within the EU and with other regions (in particular the US) to ensure that R&D efforts are not duplicated. This will require the establishment of cross-stakeholder groups to identify the necessary research infrastructure, EU-wide coordination

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activities (such as ERA net), continued support through the FPs, establishment of networks centres of excellence. One mechanism could be the development of roadmaps for the industry and the establishment of a technology watch. ACARE sees collaboration in two ways: context and commercial. While commercial collaboration is unlikely to be achieved with the US, context collaboration, aimed at “developing international standards that promote customer service and confidence, or increase society acceptance”, is a more achievable goal.

5 High Level Target Concepts (HLTC) are identified in the ACARE Vision 2020 report that will play a role in shaping the future of air transport: the Highly Customer Oriented Air Transport System; the Highly Time Efficient Air Transport System; the Highly Cost Efficient Air Transport System; the Ultra Green Air Transport System; the Ultra Secure Air Transport System. These are seen as “technology pools” which will each contribute to the changing face of air transport over the coming decades. The drivers for these changes will be external e.g. increased security threats, increased air travel restriction as a result of environmental impact, etc.

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6.3 Space Despite a decline in the commercial market for space since 2000, space exploration and exploitation is seen as a major goal for many different nations, with an increase in public spending in the USA, Russia, China and India. The leaders in space technologies at present are: the US, Russia, EU, and China (although other countries such as Japan and India have established Space Agencies and programmes). In the EU, the European Space Agency (ESA) has set forth an ambitious plan for development split into two areas: Mandatory Activities and Optional Programmes (ESA, 2005). The Mandatory Activities have a budget of €3.1 billion in the following areas in the period to 2010:

• The scientific programme (€2.1 billion) for basic R&D- covering topics in the following areas “what are the conditions for life and planetary formation?”, “how does the Solar System work?”, “what are the fundamental laws of the Universe?”, “how did the Universe originate and what is it made of?”

• The General Studies Programme (GSP) continues to develop basic science, earth observation, launchers, telecommunication and navigation, human spaceflight and exploration.

• The Technology Research Programme (TRP) looks at developing cross-cutting technology developments, including those from outside the space sector.

• The Technology Transfer Programme (TTP) focuses on commercialising new technologies through the support of new start-ups and the creation of “European Space Incubators” in ESA centres.

• The Earthnet Programme- supports the Earth Observation programme including the participation of Third countries.

• Education- development of space education offices to provide support for young students and graduates.

The level of investment for the Optional Activities is even higher (€3.8 billion). The specific projects attracting funding are: Envelope programme, ARTES programme, ISS Exploitation, ELIPS 2, ACEP (Ariane 5 Consolidation and Evolution Preparation), Ariane 5 ARTA, Vega VERTA, CSG (Guyana Space Centre) Resolution. In addition, it has a budget of €1.9 billion set aside for proposals for new activities in Earth Observation Applications, Space Exploration, Telecommunications, and Launchers. According to Dario Izzo of ESA’s Advanced Concepts Team (ACT), "the future of space flight is in using new systems, new architectures and exploring technologies to reinvent the design of space missions”. To achieve this will require both “discovery and competitiveness”. The Technology Transfer Programme has been very successful not only for the aerospace industry but the wider economy. According to the ESA website

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(www.esa.int/SPECIALS/Technology_Transfer/SEMZ5TRMD6E_0.html), it has resulted in:

• more than 200 successful transfers of space technologies to non-space sectors;

• over €800 million cumulative turnover generated in both space and non-space sectors;

• over 30 new companies established as a direct result of exploiting technologies;

• around 1500 jobs created yearly;

• more than €30 million attracted in venture capital and funding;

• a portfolio of over 450 active space technologies available for transfer and licensing;

• some 15 start-ups within the European Space Incubator (ESI);

• some 36 incubators within the European Space Incubator Network (ESINET).

Examples of inventions that have applications in other industrial sectors include: airbags, carbon brakes, navigation systems, vibration damping, insulation, cooling systems and many more. Recently, Formula 1 has utilised advanced technologies developed within the aerospace industry to design lighter cars. Galileo (a joint programme between the ESA and the EC) finally moved towards becoming a reality with the launch of its first satellite (GIOVE-A) on the 28th December 2005. In 2008 the ESA’s Columbus laboratory will be launched to the International Space Station (ISS). The primary commercial agency for fulfilling the EU’s space aspirations is EADS SPACE, which employs over 11,000 people. EADS SPACE is a wholly owned subsidiary of the European Aeronautic Defence and Space Company (EADS) and is the European authority on civil and military space transportation and manned space activities. It designs, develops and produces Ariane launchers, the Columbus laboratory and the ATV cargo vessel for the International Space Station, atmospheric re-entry vehicles, ballistic missiles for France’s nuclear deterrent force, propulsion systems and space equipment. In 2004 it had revenues of €2.6 billion with an order backlog of €11.3 billion. Another company within EADS SPACE, Astrium, is responsible for the design and manufacture of satellite systems for both civilian and military telecommunication and Earth observation purposes. In the US even larger budgets are available: in 2004 NASA had a budget of 16 billion USD, while the Department of Defence had 18.6 billion USD. NASA is investing in commercial space transportation by opening up a competitive tender for supply to the International Space Station (ISS). Two industrial partners (Space Exploration Technologies [SpaceX] and Rocketplane-Kistler [RpK]) will each share approximately 500 million USD to achieve this goal, however the partners will only receive this money if

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they are successful (payments will be made in stages based on achieving targets). The US is focused on 2 priorities: space exploration (particularly a manned mission to the moon, and then to Mars) and the use of space in support of homeland security and defence. Of all the countries involved in space exploration, Russia still remains the one launching the greatest number of spacecraft. The Russian Federal Space Agency is responsible for space science research, with a budget of some €12.5 billion from 2006 to 2015 (Forbes, 2005). It plans to develop a new re-usable spacecraft called Kliper (although a suitable contractor has yet to be identified), two new launching pads, send missions to one of the two moons orbiting Mars, and double the number of earth orbiting satellites to 70. On 10 March 2006, Russia, the EU and ESA signed a cooperation agreement on space, stimulating agreement between the Russian GLONASS and the European Galileo satellite navigation systems. The EU and Russia are also engaged in a dialogue on space cooperation, including science and technology. The EU is also collaborating with Canada and the USA on a bilateral basis and in the International Space Station. China is one of only 3 countries to have put a person in space (in 2003 using the Shenzhou spacecraft) (China, 2006). The Chinese Space Programme contracts most of its work to the state-owned China Aerospace Science and Technology Corporation (CASC), which has registered capital of 1.1 billion USD (€860 m) and employs 110,000 people. China has plans to send unmanned and manned flights to the moon, and is in negotiations with Russia over joint missions to the moon and Mars. It is also looking to collaborate more closely with the EU after the US blocked closer cooperation with the ISS (BBC). Japan established its own space agency, JAXA (Japan Aerospace Exploration Agency) on the 1st of October 2003 with the merger of 3 organisations: Japan's Institute of Space and Astronautic Science (or ISAS), the National Aerospace Laboratory of Japan (NAL), and Japan's National Space Development Agency (NASDA). It aims to achieve a leading global position in reliability and capability for both launch vehicles and satellites, and has plans for human spaceflight and exploitation of the moon. In the interim it has plans nearer to earth- to develop a supersonic aircraft capable of flying at Mach 5 that would cut the flight time between Japan and the US to a few hours. JAXA’s vision comes with large investment, around 258-280 billion yen p.a. (€1.7-1.9 billion) over the first 10 years of the strategy. The Indian Space Research Organisation was established in 1972 and has developed launch vehicles (Polar Satellite Launch Vehicle, and Geosynchronous Satellite Launch Vehicle) for its own use and those of international customers, and satellite systems for telecommunications and earth observation. It employs 20,000 people and has a budget of approximately €550 million. India aims to put an astronaut in space by 2014 (a programme that is estimated to cost €1.7 billion, www.isro.org). One of the major challenges to the EU space industry is the fact that in the US over 75% of funding for R&D comes from the Department of Defence and NASA (while in the EU it is 50%). Turnover in the EU is also

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significantly lower than the US (€5 500 million compared with €33 700 million, 1999 figures). This inevitably puts EU industry at a competitive disadvantage, and will require continued and concerted action at the EU level. In this respect FP7 funding for space related R&D is €1.4 billion from 2007 to 2013, approximately a four-fold increase from FP6 (European Commission FP7 fact sheet).

6.4 How can Nanotechnology Impact on these Strategies? The aerospace industry is already making use of composite materials to reduce the weight of structural components. In the future it is envisaged that nanocomposites will offer not only enhancements in strength and reduced weight but also added functionality, such as decreased ability to form or retain ice (e.g. on aircraft wings). Nanomaterials in engine components could also improve fuel efficiency, as well as delivering alternative future propulsion systems. The impact will be on fuel economy, pollution and noise pollution. In space applications, nanotechnology is expected to impact on fuel and energy systems, structural materials for launch vehicles (e.g. heat-resistant coatings) and electronic sub-systems. As described above, advances in nanotechnology with applications to these areas are expected also to be spun-out into other industries.

6.4.1 Patenting of Nanotechnology Advances that have Applications in the Aerospace Industry A total of 62 patents were identified using the European Patent Office (EPO) web portal (which also provides information on other patent offices)16 using search criteria for nanotechnology with keywords related to aerospace applications (see Figure 1). On closer inspection of each patent’s abstract and description only 46 of these appear to be based on nanotechnology applications. The distribution of these patents by search term is shown in Figure 1 and by country in Figure 2. The title and abstract for each patent is given in Table 1. In contrast, the worldwide patent database contains approximately 28,172 entries for “nanotechnology for information processing, storage and transmission”, 27,115 entries for “nanotechnology for materials and surfaces”, 10,960 entries for “nanotechnology for interacting, sensing or actuating”, 18,024 entries for “nano-optics”, and 16,090 for “nanomagnetics”, and more than 100,000 results for nanotechnology in total. It is likely, although not explicitly stated, that many of these patents will have potential applications in the aerospace industry.

16 See www.espacenet.com/access/index.en.htm

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Numbers of Patents in the Nanotechnology Section using different key word searches

4

15

7

5

1 1 1

17

0

2

4

6

8

10

12

14

16

18

A B C D E F G H

A Nanotechnology and aerospace E Nanotechnology and rocket B Nanotechnology and aircraft F Nanotechnology and airplane C Nanotechnology and satellite G Nanotechnology and aeronautic* D Nanotechnology and spacecraft H Aircraft; aviation; cosmonautics and nano* Figure 6.1. A-G: numbers of patents in the category “nanotechnology” using the search terms: “aerospace”, “aircraft”, “satellite,” “spacecraft”, “rocket”, “airplane”, “aeronautic*”. H: numbers of patents in the category Aircraft; aviation; cosmonautics using the search term “nano*”. No results were returned for “nanotechnology” plus “space exploration”, “extraterrestrial” or “aviation”, or “apparatus for, or methods of, winning materials from extraterrestrial sources” and “nano*”. There were 5 duplicated results between the searches giving a total of 46 patents. The patent landscape for nanotechnology applications in aerospace is dominated by the US (23 of the patents) followed by Germany (9 patents) and France (6 patents) see Figure 2.

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Global Nanotechnology Patents with Application to the Aerospace Industry

23

9

6

2

21 1 1 1

USGermanyFranceJapanCanadaItalySwedenChinaKorea

Figure 6.2. Number of nanotechnology patents with applications in the aerospace industry by country. The patents fall into a number of different categories including: materials, surface treatment and coatings, components for engines, batteries, propellants, electronics. Table 6.1. Nanotechnology patents listed through EPO website (http://gb.espacenet.com/) with applications stated for the aerospace industry. Patent Country Number of

times filed Article comprising a fine-grained metallic material and a polymeric material

CA 1

Object identification using quantum dots fluorescence allocated on Fraunhofer solar spectral lines

CA 1

Method for preparing micro powder containing anti-agglomerated nanometre silver, micro powder produced by the method and its application

CN 1

Epoxy resin having improved flexural impact strength and elongation at rupture

DE 1

Preparation of nano composites by organic modification of nano filler useful as a paint, adhesive, casting composition, in aircraft construction, electronics, automobile finishing, and as a parquet flooring lacquer

DE 1

Freshwater system in a commercial aircraft DE 1 Waterless vacuum toilet system for aircraft DE 1 Toilet system with reduced or eliminated flushing requirement, especially for transportation vehicles

DE 1

Body contacting media has surfaces with micrometric- or nanometre structuring, adapted to the respective media

DE 2

Cabin window arrangement for an aeroplane DE 1 Toilet system, particularly for vehicles DE 1

Surface treatment for aerospace applications, etc includes changing surface roughness measured perpendicular and in

FR 1

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plane of surface before applying adhesive or decorative material Space and time modulator for X-ray beam FR 1 Process for producing organized powders by spraying from at least two sets of particles, and organized powders thus obtained

FR 2

Metal/metalloid nitride/carbide ceramic powders prepared by flash pyrolysis

FR 1

Ammunition or ammunition part comprising a structural element made of energetic material

FR 1

Method to manufacture X ray mirrors with thin film multilayer structures by replication technique

IT 1

Magneto static wave device JP 1 Quantum wire structure JP 1 Carbon nano particles having novel structure and properties KR 1 Reactor for decomposition of ammonium dinitramide-based liquid monopropellants and process for the decomposition

SE 1

Reinforced foam covering for cryogenic fuel tanks US 1 Self-cleaning super hydrophobic surface US 1 Novel carbon nanotube lithium battery US 1 Electrically conductive polymeric foams and elastomers and methods of manufacture thereof

US 2

Systems and methods for modifying ice adhesion strength US 5 Dark field, photon tunnelling imaging probes US 1

Broadband light-emitting diode US 1 Aluminium matrix composite and method for making same US 1 Electromechanical memory cell US 1 ESD coatings for use with spacecraft US 2 Uncooled tunnelling infrared sensor US 1 Embedded nanotube array sensor and method of making a nanotube polymer composite

US 1

Transparent composite panel US 1 Magnetorheological nanocomposite elastomer for releasable attachment applications

US 1

Nanocomposite layered airfoil US 1 Oya computerized glider US 1

Spacecraft sculpted by solar beam and protected with diamond skin in space

US 1

Entries found using the search terms that contain no obvious nanotechnology applications: Patent Country Number of

times filed Turbofan or turbojet arrangements for vehicles craft, aircraft and the like

ES 2

Improved lighting system lamp units used on airport taxi-ways, takeoff and landing runways

FR 1

Exposing process for electronic beam JP 1 Device and method for detection of aircraft wire hazard US 2 Dry cooled jet aircraft run-up noise suppression system US 1 Tilt-tester US 1 Method and apparatus to produce ions and nanodrops from taylor cones of volatile liquids at reduced pressures

US 2

Smart docking surface for space serviceable nano and micro satellites US 1 Power sphere nanosatellite US 1 Light shield for an illumination system US 1 Dual spectrum illumination system US 1 Method for producing extreme microgravity in extended volumes US 1 Nano-G research laboratory for a spacecraft US 1

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6.5 Role of SMEs As described above, SMEs are seen as a crucial component of the aerospace industry as they provide both services and additional expertise in R&D to that of the major corporations. Ensuring that SMEs can engage effectively in R&D with each other and other organisations is therefore a key element for the future success of the European aerospace industry. AeroSME is one of the main instruments that have been set-up to aid the involvement of SMEs in EU-funded projects in aerospace. It is a joint activity between the AeroSpace and Defence Industries Association of Europe (ASD) and the EC, and includes 32 countries: the 25 EU member states, plus Bulgaria, Iceland, Israel, Norway, Romania, Switzerland, and Turkey. On the website is a database of over 1000 SMEs which can be searched by country, technology or keyword. Using “nano” as keyword search term however identifies only two SMEs: Bekaert Dymonics NV (www.bekaert.com/dymonics), which specialises in surface treatment technologies and NanoCraft (www.nanocraft.de), which specialises in coatings and material analysis and characterisation. Other initiatives to support SMEs include: European Communities Aeronautics REsearch+ (ECARE+) which is funded under FP6 from 01.02.06 for 30 months. It both networks aeronautical SMEs and allows prospective project coordinators to identify “research-intensive SMEs”. SCRATCH is another EU-funded project that supports SMEs in the aeronautics industry to establish consortia and submit project proposals to the EC. The NAVOBS+ project which supports the participation of SMEs in R&D projects in the field of Space infrastructures (e.g. satellites).

6.6 Conclusions Europe is in a relatively strong position as regards its current market share in aviation technologies. However, this is not the case for space technologies, which are largely dominated by the US. Much of this can be attributed to the high level of public funding for aerospace research in the US (particularly for space) through the Department of Defence and NASA, to maintain the stated US objective of “supremacy in aerospace”. Furthermore, there is significant overlap in aerospace R&D for civil and military purposes, which can further compound the competitive disadvantage of EU industry, as certain technology developments in the US are subject to restrictive trade agreements. Ultimately this means that an EU manufacturer may not be able to include US technology if the final product (e.g. aircraft or satellite) is sold to a country with which the US has trade restrictions. In other cases, devices may be subject to incorporation, or the final product validated, by the US manufacturer or

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approved organization. In the absence of a comparable EU technology this has the potential to severely restrict markets. Through advances in nanotechnology it is expected that the aerospace industry will be able to address issues of improved and novel propulsion systems, and decreasing environmental impacts. Other applications include communication and navigation. Advances in materials will be through decreasing the weight required for structural components (through increased strength, ductility, wear resistance, etc) thus reducing fuel consumption, and increasing their functionality (e.g. engineering anti-fouling surfaces). In the longer term, nanotechnology enabled systems should provide novel energy production and storage, sensors and electronics. To achieve this and to ensure that critical technologies will be developed by EU R&D requires the ongoing support of large-scale collaborative projects through the Framework Programmes. The involvement of appropriate authorities such as ACARE and the ESA is essential to ensure that this funding is targeted to the best projects to achieve the long-term strategic goals.

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Chapter 7: Environment, Health and Safety Aspects

7.1 Introduction Applications of nanotechnology in the aeronautics and space sectors are rather new in themselves. Therefore, little research has been done on Environment, Health and Safety aspects of nanotechnology in aerospace; EHS will be used as shorthand for the three fields. On the one hand, the potential health and environmental risks of engineered nanoscale materials for all applications constitute a great concern for policy makers worldwide.17 In the USA, EU and its member states and other countries, research strategies have been developed (e.g. Maynard et al, 2006) and projects started in the last few years to assess the toxicity of different kinds of nanomaterials and to develop exposure scenarios for humans, animals and the environment. It is uncertain how the size and surface to volume ratio of materials with particle sizes between 1 and about 100 nm influence toxicity as compared to the bulk materials. As demonstrated in earlier chapters, a considerable variety of nanostructured materials and nanodevices are aimed at incorporation in aeronautics and aerospace in the future. In many cases, e.g. in polymer matrix composites, the nanoparticles will be fixed in a matrix and potential health and environmental risks may be mainly expected during production and in waste processing or recycling. During normal use, such fixed nanoparticles may be released in the environment due to wear (abrasion) or by accident. Most concern is focused on free engineered nanoparticles which may be released in the air, water or soil. For applications of nanomaterials in aerospace, airborne nanoparticles in the cabin or released from the plane or spacecraft in the air are likely to constitute the biggest potential hazards. The aerospace production shop floor will be one of the first locations affected by potential release. Nano workplace health & safety issues, in most cases, will be addressed early on before shop floor production is considered. With nano modified composites, a universal issue involves standard shop floor processing (sanding, drilling, cutting, etc.).The postulation that these abrading processes will not release free engineered nanoparticles will be challenged. "Best practice" engineering controls and PPE (personal protective equipment), as required, will certainly be applied. At the Dec.2006 International Conference on Nanotechnology Occupational and Environmental Health and Safety (NOEHS), Battelle

17 See e.g. Nanoforum, 2005 and click the button “safety and environment” on top of the page www.nanoforum.org for an overview of recent developments and publications.

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Toxicology Northwest presented results of a release comparison study of simulated Boeing shop floor sanding a "control" composite versus a nano modified composite. This exposure risk study was thought to be one of the first to evaluate, under controlled conditions, the possibility of free engineered nanoparticle release from standard shop floor processing. The general debate about EHS aspects of engineered nanomaterials in the workplace is also relevant to aerospace industry. A review of this debate goes beyond the scope of the present report. Relevant news and publications can be found elsewhere at the Nanoforum site or through other media. On the other hand, introducing nanomaterials or nanodevices such as sensors into aeronautics can also bring environmental, health and safety benefits. Environmental benefits include less use of energy and materials. Health benefits can arise from incorporating nanosensors monitoring on board air and water quality, filters for purifying air and water etc. Safety may be improved by applying fire retardant nanomaterials, integrating nanosensors networks in composite materials to monitor structural integrity of the hull, remote sensing applications and other nanomaterials and devices. In this part of the report, we summarise the available literature and come up with suggestions for further research. The focus is on response to engineered nanoscale materials explicitly intended for application in the aeronautics or space sectors.

7.2 EHS risks Environment, Health and Safety aspects of nanomaterials in different applications including aerospace applications were the topic of a Delphi study carried out in the AC/UNU Millennium project (Glenn and Gordon, 2005). Aerospace applications which may lead to EHS impacts in 2005-2010 include the following18: Application: Potential EHS impact: Nanoparticles in fuel as additives Inhalation by staff but also by the

population in general

18 Source: AC/UNU Millennium project : « Environmental and Health Hazards resulting from military uses of nanotechnology, round 2 : www.acunu.org/millennium/nanotech-rd2.doc

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Nanoparticles as surface coverage to make it harder, smoother, stealthy

Erosion of these nanoparticles make them inhalable by staff but also by the general population Nanopollution in the environment and contamination of the environment (vegetables, fruits etc), humans and animals. The contamination can also infect drinkable water and fish

Boeing (2005) expects future nanotechnology applications in aeronautics and aerospace in 10-15 years and considers now a good time to investigate Environment, Health and Safety implications. The EHS risk potential of nanotechnology applied in aeronautics outlined by Boeing reflects the general global nanosafety research agenda. Boeing is represented by their Environmental Assurance group on the ASTM International Subcommittee E56.03 responsible for Nanotechnology Environmental & Occupational Health & Safety. Boeing Phantom Works and several subcontractors are working on a composite recycling project for carbon fibre composites from aircraft since 2003. These composites do not contain nanomaterials, but a similar recycling process could perhaps eventually be found useful for carbon nanotube composites. Carbon fibre composites have been applied in aircraft since the early 1990s, but were not recycled due to a lack of a market for the scrap materials. Since the late 1990s, such markets were identified and it became interesting for Boeing to develop recycling schemes. (Boeing, 2005) Nanostructured metals have been applied in aerospace since the 1990s, first in landing gear components. Lux Research (2006) does not see indications of any EHS issues with nanostructured metals, because only the grain size of crystals inside a metal matrix is of nanodimensions. The life cycle should be assessed to be sure. Lux Research and a toxicology consultant are offering an EHS audit service aiming to raise awareness among nanotech start ups and other companies of these issues. An aerospace and defence company was the first to be audited. (Thayer, 2006) The general research agenda for EHS aspects of engineered nanomaterials is also applicable to applications in aerospace. Industrial sectors such as Aerospace and Automotive have articulated similar needs as the Chemical industry on “joint nanotechnology research needs which would enable the correlation and prediction of nanostructure and properties from synthetic conditions.” (Garner, 2006)

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7.2.1 Health risks Health impacts of nanomaterials are the most pressing concern in spacecraft, because astronauts can spend months inside a spacecraft, whereas pilots, cabin staff and passengers don’t spend more than some hours at a time in a commercial aircraft. Studies have shown that modifying the surface of nanomaterials with surfactants or biocompatible polymers (e.g., polyethylene glycol) reduces the toxicity in vitro (Derfus et al., 2004) and alters the half-life and tissue deposition in vivo (Ballou et al., 2004). These findings indicate there may be many ways to reduce the health risk for astronauts who are expected to spend considerable lengths of time in a spacecraft. The magnitude of the protective response is generally proportional to the magnitude, complexity, and duration of exposure. The last factor is the main source of chronic adverse health effects. In general, the need for specific studies on the human response to nanomaterials highlights another research challenge: the limited availability of well-characterized material in sufficient quantity. Consequently, most current research is performed in vitro, not in vivo, and assesses acute exposure, not chronic exposure. Development of new test methods to evaluate novel behaviour of nanomaterials in vivo, and new in vitro tests may be necessary to predict novel in vivo behaviour. Standardized dosing protocols have yet to be established. Modifications of the surface of nanomaterials can alter biochemical reactivity and should be reflected in calculations of absorbed and effective dose. Any surface modification has the potential to strongly influence the material’s reactivity.

7.2.2 Safety risks Potential risks may in the long term occur due to more futuristic applications of nanotechnology in aerospace such as accidents with the proposed space elevator, satellites or other objects in earth orbits which may fall out of orbit or collide with each other in space. In the past, accidents caused by re-entry of satellites have been reported occasionally.

7.3 Environmental benefits Applications of nanotechnology in aerospace are expected to lead to potential benefits for the environment. These benefits include reduced fuel consumption, more environmentally sound coatings and on-board environmental control sensors. Piotr Tucholka (2002) presented some “Major challenges for environmental studies”, including the need for global monitoring of environmental conditions and better understanding and calibration of

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space based observations and their relation to parameters of the objects. He believed “nano- and micro technologies are well-suited to provide significant improvements in these applications. Several already existing applications, like those used in petroleum well monitoring are adapted or adaptable to environmental problems…” Light and strong nanomaterials (e.g. polymer nanocomposites) may be applied to produce lighter aircraft, along with other materials such as carbon-fibre reinforced plastics or alumina-based materials. (Mulcair, 2003) This may help reduce aircraft fuel consumption. However, this potential environmental benefit may be limited by rebound effects, e.g. if the lighter planes, in turn, carry a heavier load of passengers and cargo. (Ellen et al, 2005) Boeing (2005) foresees EHS benefits due to applications of nanotechnology, including waste and air emissions reductions. “Dave Whelan, (at that time) Boeing Phantom Works General Manager, commented he believes that it will make possible: ‘Specialised coatings so that planes don’t need repainting’. Also, the use of POSS (polyhedral oligomeric silsesquioxanes) may result in zero volatile organic compound (VOC) coating development.” Other advantages mentioned are not specific for the aerospace sector. The Canadian government is investing $3.4 million in development of new nanotechnology based coatings for aerospace, advancing more environmentally sound technologies. The company Integran will develop nanocrystalline cobalt-phosphorous coatings and deposition process technologies as an environmentally friendly alternative for the current hard chrome plating process used for coating landing gear and jet engine components. (CCN Matthews, 2005) Airbus is also interested in nanotechnology for enhancing the environmental friendliness of their airframes. No details are disclosed. (Woelcken et al, 2006) An important aspect is the environmental control. Spacecraft have closed-loop environments with the ability to reclaim air and wastewater. Environmental sensors distributed throughout the ship keep track of contaminants in the air and water (Meyyappan, Dastoors, 2006). Some other beneficial applications have already been mentioned in earlier chapters such as alternative energy sources for aircraft and spacecraft, lower energy consumption due to nano-surface treatment for environmental benefits.

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7.4 Health benefits Health benefits can occur if nanomaterials can replace toxic materials currently applied in aerospace, or in the form of life support systems in spacecraft and possibly also aircraft. The ultimate vision for nanotechnology in astronaut health management is to provide a quality of medical care regardless of the duration of the space mission. Scientists at Michigan University Ann Arbor’s Centre for Biologic Nanotechnology are developing nanosensors for monitoring the health impact of space radiation on astronauts. These sensors incorporate dendrimers. (Flinn, 2005) Katrin and Harald Kneipp of Harvard University have proposed nanosensors for astronaut health monitoring based on surface enhanced Raman scattering (Kneipp & Kneipp; also Kneipp et al, 2006)

7.5 Safety benefits Nanomaterials and devices are expected to enhance the safety of aircraft and spacecraft. Especially on commercial aircraft, nanosensors and smart materials can improve safety for the people on board considerably. Safety of people on board can profit from application of vibration and flame resistant nanomaterials and nanosensor networks embedded in composite materials. Safety of people on the ground and the environment can profit from improved disaster management by earth observation and satellite communication. Embedded micro and nanosensors for measuring structural integrity can be included in future generation aircraft structural components. Solutions include cantilever-based MEMS (Waitz, 2006) and other MNT-based sensors (Blue Road Research, 2006). Carbon nanotubes embedded in composites can be used as an artificial nervous system. The nanotubes make up only 0.15% of the material and are evenly distributed through the composite. By running an electrical current through the web of nanotubes, micro cracks in the material can be detected. (Thostenson, 2006)

7.6 EHS Regulation Regulating Environment, Health and Safety aspects of nanomaterials and nanodevices for aerospace applications will have to be part of the existing legislative framework for the aeronautics and space sectors. The existing relevant European Union policies and legislative framework is summarised below.

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The European Commission has reviewed and updated its Transport policy mid 2006. The EU aims to be a world leader in sustainable transport solutions. The aviation industry is consolidating at European level. EU innovation policy under FP7 includes the greening of air transport, safety and security in transport, intelligent transport systems and engine technology providing increased fuel efficiency and promoting the use of alternative fuels. Air transport accounts for 9% of EU oil consumption. The EC aims to reduce this dependence on oil supplies through innovative energy efficiency and alternative energy solutions. “Although airlines have reduced fuel consumption by 1-2% per passenger-kilometre in the last decade and noise emission from aircraft has declined significantly, the overall environmental impact of civil aviation has increased due to buoyant growth in traffic… greenhouse gas emissions from air transport have grown by over 4% per year in the last decade.” (EC, 2006, p 8) The EU is a major world player in air transport equipment. The EC wants to reduce environmental impacts whilst maintaining the competitiveness of the sector, by innovation, making engines more efficient. A broad set of common safety standards is enforced with the help of the European aviation agency EASA. On 19 October 2006, the EC has presented an Action Plan on energy efficiency. It includes strategies to stimulate higher energy efficiency of aviation through the Single European Sky Air Traffic Management Research project (SESAR, 2007-2012) and proposing legislation to include the aviation sector in the EU Emission Trading Scheme (end of 2006). This action plan builds upon the EC Communication on Climate Change and Aviation (2005) including proposals to give research into ‘greener’ technology the highest priority in FP7 and working in ICAO on developing more stringent technical design standards to reduce aircraft emissions at the source. The EC is in favour of developing green aircraft according to the thematic strategy on air pollution (EC, 2005). Currently, “aeronautical products should be subject to certification to verify that they meet essential airworthiness and environmental protection requirements relating to civil aviation… in line with standards set by the Chicago Convention”. “In order to respond to increasing concerns over the health and welfare of passengers during flights, it is necessary to develop aircraft designs which better protect the safety and health of passengers.” (EC regulation 1592/2002) In 2006, too little is probably known about the impacts of nanotechnology to determine if current regulations are sufficient. This is the general situation, and will likely apply also to aerospace. In the Dutch standards committee dealing with nanotechnology, no representatives of aerospace participate. There is currently no formal cooperation between the two ISO committees ISO/TC 229 for nanotechnologies and ISO/TC 20 for

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aerospace. When the first nano-norms appear, these are likely to be applied also to individual sectors including aerospace. The discussion about nanotechnology is starting in aerospace norms and standard setting circles. It is not yet clear if there will be a need for nanospecific norms. The European debate takes place in ECSS, and Dutch companies are involved in it. (Source Ivo van der Werff, NEN, personal communication, October 2006). In the EU funded NANOTOX–project, health and safety related to nanomaterials for applications in all sectors including aerospace are framed.19 This implies the following: “Standards, legislation, ethical issues, policies and codes of practice, at international and European level, which have been put in place or are under development, will be assessed and reviewed. Their implications and effectiveness will be discussed. Ways in which existing legislation is applied to the macroscale counterparts of nanoparticles will also be examined. Guidelines and recommendations for the institution of future European standards, legislation, ethics, policies, and codes of practise, for the safe production and use of nanoparticles will be produced.” “All potential impacts revealed by this Specific Support Action (SSA) will be documented in the final report and disseminated via the specialised web pages on the NANOFORUM web site.” The project aims “to survey national, international and European standards, legislation, ethical issues, policies and codes of practice.”

7.7 Conclusion To conclude, the discussion and investigation of EHS risks and benefits of engineered nanomaterials and nanodevices in aerospace is barely getting off the ground. There is a need for identifying the main possible concerns and opportunities. Potential specific EHS risks of nanotechnology applied in aerospace must be addressed in toxicology research and the development of specific exposure scenarios for the aeronautics and space sectors. Current research agenda’s for risk assessment of engineered nanomaterials intended for application in aerospace are relevant. These are currently focused on general toxicology and exposure scenarios in the workplace and exposure of the environment and the human body. There seems to be a need for complementing these plans with additional life cycle analysis of the materials intended for use in aerospace applications. Exposure

19 This project runs from 1 February 2005 until 31 January 2007, results will be published at http://www.impart-nanotox.org/impartnanotox/nanotox_summary.html

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scenarios due to release of engineered nanomaterials in the air at high altitudes and in the cabin environment are also needed. To obtain the optimal environment, health and safety benefits of nanotechnology in aerospace, scenarios must be developed and used to decide on research priorities and regulation. Relevant regulations should not be limited to airworthiness criteria, but also promote the use of Best Available (environmental) Techniques under the Integrated Pollution Prevention and Control policy of the EU. Communication between parties involved in standardisation of the aerospace sector and of nanotechnology also needs improvement, e.g. between the relevant ISO Technical Committees. The novelty of nanoscale materials arises from the fact that with the size decrease the properties of the materials change, which, however, may be accompanied by increased environmental, health and safety risks. Safe usage of engineered nanomaterials in aerospace requires employing strict control on atmospheric nanoparticle release from aircraft in the atmosphere because the nanoparticles could easily be distributed widely over the Earth’s surface. Whether international regulations could ever prevent potential future disasters is problematic. Development of instruments and methods for nanomaterials characterisation considered crucial for testing impacts on environment, health and safety is urgently needed. This is true for all applications of engineered nanoscale materials including aerospace and is being addressed worldwide. Specific for aerospace applications, exposure scenarios of astronauts, pilots, cabin personnel and passengers must be developed, as well as life cycle assessments of the nanomaterials applied in aircraft and spacecraft to identify possible environmental exposure scenarios. The public acceptance of some EHS aspects of nanotechnology in aerospace may be ambivalent. For example, a lighter weight aircraft might be admired for its lower fuel consumption but it could also be considered a potential risk source if its nano modified materials should in any way release free engineered nanoparticles.

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Chapter 8: Ethical, Legal and Social Aspects

8.1 Introduction Society and new technologies mutually influence each other’s development, as has been demonstrated in many case studies in the field of Science, Technology & Society (STS). Nanotechnology is one of the first emerging technologies where policy makers and researchers have initiated a deliberately constructed, large scale systematic research programme on Ethical, Legal and Social Aspects or Implications of a new science and technology area in an unprecedented early phase of development.20 In this chapter, we will not review all the literature on ethical, legal and social aspects of nanotechnology in general, but focus on the relevant issues and regulatory framework for nanotechnology applications in aeronautics and especially outer space. Most of the issues and discussions are likely to focus on outer space, since space travel and commercial uses of outer space in satellites, space tourism and other activities are more recent than large-scale air travel and transport. Issues like the use of outer space and ownership claims are still not regulated and the potential risks of human activities and the deployment of human-made technologies in outer space are highly uncertain and not addressed in any systematic way. The development and eventual uptake of aerospace applications of nanotechnology is influenced on the one hand by the parallel development of the regulatory framework for the space and also the air transport sectors in general as these nanomaterials and devices will have to conform to these more general regulations. In the aeronautic sector, most developments focus on reducing the environmental burden of air travel and on improving on-board safety and health, as discussed in chapter 7. On the other hand, nanotechnology will change current practices and norms and values governing the air transport and space sectors, because they can enable activities which were not possible or too expensive before. E.g. microsystems and nanotechnologies can enable small satellites, which can be used on a larger scale for earth monitoring, or autonomous systems for exploring other planets. Or nanotechnology may enable better life support systems in space stations and spacecraft, stimulating longer astronauts’ missions.

20 See Nanoforum (2005) or click the button “More” followed by “Society Issues” on top of the webpage www.nanoforum.org for an overview of relevant developments and publications.

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In this chapter, we first review current developments in European and international regulations governing the space sector which are relevant for nanotechnology. Then we review some early literature exploring potential ethical, legal and social implications of nanotechnology applied in outer space and aeronautics. We conclude with some suggestions for further research.

8.2 Regulations The United Nations Educational, Scientific and Cultural Organisation’s (UNESCO) World Commission on the Ethics of Scientific Knowledge and Technology is working on an international instrument on the ethics of outer space. In general, UNESCO proposes to incorporate ethical guidelines in the existing framework of UN outer space treaties and declarations. The treaties are:

- The 1967 treaty on principles governing the activities of states in the exploration and use of outer space, including the moon and other celestial bodies (outer space treaty),

- The 1968 treaty on return and rescue of astronauts, - The 1972 convention on international liability for space damages, - The 1975 convention on registration of space objects, - The 1979 agreement about the moon and other celestial bodies.

The UN assembly declarations cover the following aspects: - legal principles (1963), - satellite TV (1982), - remote sensing (1986), - use of nuclear devices (1992), - International cooperation (1996). (UNESCO, 2004, p 12)

Some of these treaties are limiting arms and military uses of outer space. See also Detlev Wolter (2006). UNESCO highlights some new issues which need to be discussed in particular: a) Motivation and interest of space conquest, b) Interest of manned flights, c) How to decide on ethical questions regarding outer space: i) Nuclear power in space, ii) limits of outer space, iii) Arbitrage between confidentiality and collective security (related

to info-ethics), iv) Determination of the status of data (e.g. the rights of observed countries vs. property),

d) Risks of abuse of dominant position by space actors, e) Responsibility in case of catastrophe.21 21 See UNESCO website: http://portal.unesco.org/shs/en/ev.php-URL_ID=6353&URL_DO=DO_TOPIC&URL_SECTION=201.html

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The European Union (EU) is developing a European Space Policy. The European Commission has published a Communication on European Space Policy – Preliminary Elements in May 2005 (European Commission, 2005). The aim is to develop a strategy for space technology development coordinating the activities of the EU, European Space Agency (ESA) and EU Member states as well as other countries including Russia, the United States (US), China and Israel. They are also developing a regulatory and institutional framework, in which the current principles of governance in space can evolve, the strategic benefits of space can be recognised and ESA can be maintained as Europe’s pole of excellence. The communication envisages at least five scenarios for developing a legal framework and recommends assessing all of them. The scenarios deal with who should take the lead in managing and funding regulations and space activities, the roles of EU, ESA, member states, national space agencies and other organisations. The EU space policy includes international collaborations including “aspects of international trade ‘fair competition’ and market access through the regulatory environment (WTO, export controls, licensing, allocations of frequencies and orbital slots within the International Telecommunications Union).”22 The EU is coordinating a common European – United Nations position on the political, legal and technological components of space affairs.23 The US President established the White House’ new National Space Policy on 31 August 2006. They declare the conduct of US space programs and activities a top priority, guided by a number of principles, which seem to imply that the US reserves the right to protect their own national security in space, while denying adversaries the use of space capabilities hostile to the US national interests. At the same time they will oppose the development of new legal regimes, other restrictions or arms control agreements restricting US activities. As part of the strategy they do intend to encourage international cooperation with foreign nations and/or consortia on space activities that are of mutual benefit and that further the peaceful exploration and use of space as well as US national interests. The policy includes effective export policies, implying that technologies which are or will soon be available on the world market can be exported freely, but that “export of sensitive or advanced technical data, systems, technologies and components, shall be approved only rarely, on a case-by-case basis. These items include systems engineering and systems integration capabilities and techniques or enabling components or

22 See: http://ec.europa.eu/enterprise/space/themes/inter_cooperation_en.html 23 See: http://ec.europa.eu/enterprise/space/themes/inter_cooperation_en.html

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technologies with capabilities significantly better than those achievable by current or near-term foreign systems.” (US White House, 2006) Among the goals of expert control policies for sensitive goods is to block or slow down access to militarily relevant equipment. The EU is party to many such arrangements. René Oosterlinck (2006), ESA director of external relations, explained developments in space law. The current legislation is ambiguous on several aspects including mineral exploration on asteroids and intellectual property rights for research in space, such as in the International Space Station. Also who is responsible for space debris is not settled. He pleads for a review. The current developments of international and national space policies as described above are of course on the table of the politicians and are not easily influenced by researchers working on nanotechnology. Researchers do exert some influence on policy makers, in particular concerning extrapolations into the future, guiding visions, etc. Researchers must be aware of their responsibility. On the other hand, these political developments determine the boundaries in between which the researchers have to do their work on developing nanotechnology for applications in aerospace, as demonstrated by recent discussions at the CANEUS 2006 conference in Toulouse, France. During this conference, a short course has been held on “International Traffic in Arms Regulations (ITAR) – Intergovernmental agreements, Flight Opportunities, Standards, export policy restrictions, Environmental, Safety.” The main focus was on US expert restrictions on defence related technologies as applicable to Microsystems and Nanotechnologies for aerospace. The Strategic Research Agenda of the European Space Technology Platform (ESTP, 2006, p 37) also mentions these ITAR restrictions, which apply to satellite technology and all electronic and other space components or subassemblies. This is the case since 1999, when the US Congress transferred responsibility for satellite technology from the Commerce department to the State Department. About 60% of the electronic components and equipment needed for a typical satellite are imported from the US, 5% from other countries and 35% are made in the EU. The EU has since developed a strategy of “non-dependence”: having unrestricted access to any required space technology from European or other suppliers. ESA has started a European Components Initiative in 2004, aiming to reduce substantially the dependence on components subject to US export restrictions. ESTP proposes to continue this ECI and develop similar “buy European” programmes for other critical space components, while maintaining the quality of the European technologies. During the abovementioned CANEUS 2006 conference an NPS industry working group was installed, which aims for standardisation of small

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satellites. The first meeting has been in Montreal, 25 October 2006. (Caneus, 2006)

8.3 Ethical, Legal and Social Aspects Most Ethical, Legal and Social issues are related to outer space, as opposed to air travel and terrestrial policies. The international community is currently in the process of developing ethical declarations, treaties and legislation to govern human activities in outer space as has been reviewed above. The more detailed discussion of how the uptake of nanotechnology in aerospace may lead to new ethical, legal and social issues is reviewed below. These issues can be divided in two groups:

1) Implications for privacy, security and safety of humans and our earthly society and environment;

2) Ethical implications of applications of nanotechnology in planetary and outer space exploration, e.g. in the case of sending out autonomous “thinking” systems to other planets and who is responsible for what they do there, carrying out risky experiments in outer space or attempts at terraforming other planets.

The first group is a more immediate concern, because the earth observation and communication satellites are already there, and nanotechnology can only be a factor in making them smaller, cheaper and increasing their use. These implications should be viewed in the context of decades. How we structure nanotechnology related outer space use today will influence development for decades. The second group is a very long term concern, but nevertheless discussed already by proponents as well as opponents. We show progress in the discussion by briefly summarising relevant literature in chronological order. Societal implications of nanotechnologies and studies needed are outlined in section 6.5 on “Social, Ethical and Legal Implications of Nanotechnology” of the US National Science Foundation (NSF) report on Societal implications of nanotechnology (Roco & Bainbridge, 2001).24 Richard H. Smith includes several positive opportunities of nanotechnology for outer space exploration, including reduction of the payload to energy ratio which may enable new missions, using other planets as quarantined nanotechnology test beds, and considering terraforming other planets. UNESCO mentions Nanotechnology explicitly as a bioethical issue in its work on the ethics of outer space: “Specific bioethical issues may be raised by experiences in outer space, starting with the question of the adaptation of humankind to outer space. There is also largely an issue of risk, and the determination of the possibility of contamination either of or

24 http://www.wtec.org/loyola/nano/NSET.Societal.Implications/nanosi-s65.pdf

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from outer space. The compatibility of life science experiments in outer space and their return to Earth should also be studied. This issue is also linked to the ethical concerns raised by nanotechnology”. (UNESCO, 2004, p 10-11) The US National Aeronautics and Space Administration’s (NASA) Grand Challenges for nanotechnology in Aerospace are:

- Autonomous “thinking” spacecraft - Safe, affordable aviation - Human exploration and colonisation of outer space - Evolution of Universe and Life (NASA, 2006)

One can imagine that the potential development of autonomous “thinking” spacecraft invokes ethical concerns. The debate about ethical aspects of human enhancement, human-machine interactions and artificial life is in general emerging. Jürgen Altmann (2006) proposes preventive arms control on nanotechnologies which may be used for military applications. There is a need for a comprehensive ban on space weapons. This has been demanded nearly unanimously by all recent UN General Assemblies. He includes explicitly civil nanotechnology developments in aviation (aeronautics). “In aviation, much of military as well as civilian R&D takes place in the same institutions and firms, with knowledge flowing in both directions.” He proposes to prevent misuse of civilian R&D for military purposes by strong verification rights, allowing independent inspectors to control compliance on site. “With respect to Nanotechnology, this might apply to small satellites; a significant number could be allowed for civil Earth monitoring or space research if subject to intensive licensing and inspection procedures while military satellites would be strictly limited.” (Altmann, 2006, p 132) “Small and/or more autonomous satellites, if used for anti-satellite attack, would counteract the general ban on space weapons that the international community has striven for since decades.” (Altmann, 2006, p 136) He warns for two military uses of swarms of small satellites: observation and detection of targets on earth guiding attacks, or attacks to other satellites in orbit. (Altmann, 2006, p 139-140) Altmann (2006, p 167) foresees the deployment of mini- or micro robots for exploration of the moon, planets and asteroids. If “swarms of centimetre size flying or crawling robots for moon and planet investigation” were developed, “cheap production of hundreds or thousands could lead to diffusion to uses on earth”. He proposes a “general prohibition of small mobile (partly) artificial systems below a certain size limit (0.2 to 0.5 metres) in all media, in the military and the civilian sector.” “Exceptions should be strictly defined and narrowly limited … they could concern exploration of celestial bodies.” He proposes technical limitations and licensing procedures to prevent misuse.

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Security measures are inherently ambiguous. While carried out in the interest of one’s own security, it often decreases the security of others, leading to arms races and decreased stability (security dilemma). The way out of this dilemma is agreed international limitation with verification of compliance. Patrick Lin (2006) explores potential ethical issues of space exploration. He predicts that applications of nanotechnology in space may enable such a new colonialism and land-grab, such that these developments should be regulated from the start to avoid conflicts related to fundamental property rights, administration and security. Even though he mentions nanotechnology, the argumentation is more general space ethics, including the rationale to explore space in the first place.

8.4 Conclusion Current developments in international and national politics and negotiations on international treaties and declarations are in progress in small parts of especially the space sector. These developments are only to a limited extent influenced by nanotechnology, but the development and uptake of nanotechnology in aerospace is fenced in and guided by these global political developments. Researchers in nanotechnology for aerospace are forced to take these boundary conditions into account in planning their research and in selecting partners in other countries. The uptake of nanotechnology in outer space is in the short time likely to strengthen the urgency of existing ethical concerns such as privacy, security and safety of people and the environment on earth, as miniaturisation will lead to cheaper and more abundant satellites orbiting earth. In the long term nanotechnology may lead to new ethical concerns caused by new human initiated activities on other planets or even outside our solar system. The debate on such longer term but not unprecedented developments is barely emerging. We propose some suggestions for further research:

- Current and proposed projects on Ethical, Legal and Social Aspects of science or on Ethics of Science focusing on nanotechnology and on aerospace (aeronautics as well as outer space) should be further reviewed to explore issues in the boundary area between them which are currently overlooked. Such additional research should not distinguish between military and civilian research as this distinction does not really exist in the aerospace sector.25 Subsequently, new

25 The Nanoforum contract precludes covering military activities; therefore we had to make this distinction in the present report.

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research projects should be initiated which focus on newly identified issues of major concern to society.

- An inventory of regulations on aeronautics should also be prepared in addition to the list of outer space treaties. A main new topic for nanotechnology use in air traffic could be crewless aircraft. These are becoming available first in military, and later in civilian air traffic. Mini- and micro-aircraft are becoming available for military uses, but may also be appropriated by terrorists in the longer term.

- Educational programs at schools and universities are needed which combine nanosciences, nanotechnologies, aerospace applications and social, legal and ethical aspects. Two types of programmes should be developed. The first type of programmes should educate the nanotechnology and aerospace workforce. The second type of outreach activities should enhance public awareness of the potential benefits and risks of nanoscience and technology including those specific for aerospace applications.

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References 3sat, Webpage, 2001, „Die kalte Gefahr - Neue Technik gegen Vereisung am Flugzeug“, http://www.3sat.de/3sat.php?http://www.3sat.de/nano/astuecke/14480/index.html

Abdalla I.; Rahimzadeh T.; Trueman C.W.; Hoa S.V., SAMPE'06: Creating New Opportunities for The World Economy: vol. 51. Proceedings of a conference held in Long Beach, Ca., 30th April-4th May 2006. Editor(s): SAMPE Covina, Ca., SAMPE International Business Office, 2006, Paper 61. ACARE, Advisory Council for Aeronautics Research in Europe, October 2004, Strategic Research Agenda, Volume 1, http://www.acare4europe.org/docs/ASD-volume1-2nd-final-ss%20illus-171104-out-asd.pdf ACARE, Advisory council for research in Europe, 2004. Strategic Research Agenda – Vol 2. Available from: http://www.acare4europe.org/docs/ASD-Annex-final-211004-out-asd.pdf

Advanced Materials, “Mechanical Reinforcement of Polymers Using Carbon Nanotubes,” Advanced Materials 18, 689-706 (2006).

AFRL, “AFRL’s Materials and Manufacturing Directorate, Non-metallic Materials Division, Polymers Branch, Wright-Patterson AFB OH, USA

Mike A’Hearn, “Sens systems”, Aerospace America p 40-41, 2005 http://www.aiaa.org/aerospace/images/articleimages/pdf/sensor%20sys.pdf

AIAA, Plasma arc soften jet engine noise. American Institute of Aeronautics and Astronautics. 2005 Available at:

http://www.aiaa.org/aerospace/images/articleimages/pdf/notebookjanuary05.pdf

Airbus, Global Market Forecast 2004-2023, www.airbus.com/en/airbusfor/analysts/

Jürgen Altmann, “Zusammenhang zwischen zivilen und militärischen Hochtechnologien am Beispiel der Luftfahrt in Deutschland“, in J. Altmann (ed.), „Dual-use in der Hochtechnologie – Erfahrungen, Strategien und Perspektiven in Telekommunikation und Luftfahrt“, Nomos, Baden-Baden, 2000

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Jürgen Altmann, “Military Nanotechnology. Potential applications and preventive arms control”, Routledge, Oxon, UK 2006 Marlys Amundson, “UCLA engineers Pioneer Lab-on-a-chip blood test”, UCLA engineering, 2006 http://www.engineer.ucla.edu/magazine/fall06/bloodtest.html V. Aroutiounian, “Quantum Dots Solar Cells”, Journal of Applied Physics 89, 2268, 2001 ASTM committee E56, Subcommittee for Nano Environmental & Occupational Health & Safety: http://www.astm.org/cgi-bin/SoftCart.exe/COMMIT/COMMITTEE/E56.htm?L+mystore+plpm4335+1107370479 AzoNano, February 27, 2004, “Samsung Launches Nano e-HEPA Air Purifier System“, http://www.azonano.com/details.asp?ArticleID=560 AZNano. 2005. Available at: http://www.azonano.com/news.asp?newsID=1208 Susanne Bader, B. Stumpp, “Materialmix: Die Einsatzart entscheidet”, Produktion Technik, No. 40, Oct. 5, 2006. This article can be downloaded via http://www.produktion.de/article/b76122ae27d.html, but is not for free. B. Ballou, B.C. Lagerholm, L.A. Ernst, M.P. Bruchez, A.S. Waggoner, Bioconjugate Chem. 15(1), 79-86 (2004). David J. Barnhart et al., “Satellite-on-a-chip: a feasibility study”, University of Surrey, 2005 Patrick L. Barry, “The next Giant Leap”, NASA, 2005 http://science.nasa.gov/headlines/y2005/27jul_nanotech.htm BBC: China's vision for new space age http://news.bbc.co.uk/1/hi/sci/tech/3876373.stm Bhowmik S.; Bonin H.W.; Bui V.T.; Weir R.D., Journal of Applied Polymer Science 2006, 102 (2), 1959-1967. Blue Road Research, Inc, “MNT-based sensors for aircraft/spacecraft structural health monitoring”, Concept paper 11a, CANEUS, 2006, www.caneus.org L. Boehm, “Nano-materials for aerospace and security applications”, http://www.yosh.ac.il/research/mmt/WS2006/Papers/004.doc

139

Boeing, Press Release Oct. 6, 2005, “Boeing, Ford and Northwestern University To Launch Technology R&D Alliance”, http://www.boeing.com/news/releases/2005/q4/nr_051006a.html

Boeing, “EHS aspects of Nanotechnology”, Boeing Environmental Technotes Volume 10, Number 1, February 2005, The Boeing Company, St. Louis, MO, USA, http://www.boeing.com/companyoffices/doingbiz/environmental/TechNotes/TechNotes2005-02.pdf Boeing, “Composite Recycling Revisited”, Boeing Environmental Technotes Volume 10, May 2005, The Boeing Company, St. Louis, MO, USA, http://www.boeing.com/companyoffices/doingbiz/environmental/TechNotes/TechNotes2005-05.pdf Burghardt J.; Hansen N.; Hansen L.; Hansen G. Proceedings of a conference held in Long Beach, Ca., 30th April-4th May 2006. Editor(s): SAMPE Covina, Ca., SAMPE International Business Office, 2006, Paper 131 Ed Campion, “NASA works with new company to bring nanotube technology to the commercial marketplace”, NASA, 2006 http://www.nasa.gov/centers/goddard/news/nanotube_tech.html CANEUS, “Caneus 2006 conference summary”, http://www.caneus.org/home_news4.html Caneus. 2006. Proceedings Available at: http://www.caneus.org/proceedings.html CANEUS, 2004, “MNT-based Sensors for Aircraft/Spacecraft, Structural Health Monitoring“, http://www.caneus.org/RFP2004/A11.pdf

CANEUS, “Micro-Nanotechnology for space applications”, centre for large structures and systems (CLS3), 2002, http://www.caneus.org/reference/Chapter_3.pdf http://www.caneus.org/reference/Chapter_5.pdf China's Space Activities in 2006 www.cnsa.gov.cn/n615709/n620682/n639462/79381.html

Mircea Chipara: « Spzce materials: the final frontier » Materials Today, July/August 2005

Cohen L.A.; Lippold M.; Tolis S., SAMPE’05: New Horizons for Materials and Processing Technologies. Proceedings of a conference held in Long Beach, Ca., 1st-5th May 2005. Editor(s): SAMPE Covina, Ca., ACS, SAMPE International Business Office, 2005, Paper 133.

140

Colavita M.; Bowler A.; Xiang Zhang.; Irving P.E., Proceedings of a conference held in Long Beach, Ca., 30th April-4th May 2006. Editor(s): SAMPE Covina, Ca., SAMPE International Business Office, 2006, Paper 17.

Delft University of Technology and Systematic design B.V, “Delfi C3: a student nanosatellite test-bed for in-orbit demonstration of micro systems technology”, 2005 A.M. Derfus, WC.W. Chan, S.N. Bhatia, Nano Lett. 4(1), 11-18 (2004) Diehl, 2005, Project “OLED applications in aircraft”, http://oas2.ip.kp.dlr.de/foekat/foekat/einzeldarstellung?p_fkz=13N8949

Dunn D., Adhesives and Sealants Industry 2006, 13 (9), 34-36.

E. Durgun et al., “Transition-metal-ethylene complexes as high-capacity hydrogen-storage media”, Physical review letters, 97 226103, 2006 EADS, 2007, “Nanotechnology - the key to a new ear”, http://www.eads.net/web/printout/en/1024/content/400004/5/06/41143065.html

Edwards, B.C., 2000. Design and deployment of a space elevator. Acta Astronautica, Volume 47, Issue 10, 735-744.

Gerald-Jan Ellen, Christien Enzing, Helma Luiten, Mario Willems, “Nanotechnologie en de kansen voor het milieu”, TNO Rapport I&R 2005-17, TNO, Delft, 1 September 2005, downloadable from: http://www.tno.nl/bouw_en_ondergrond/producten_en_diensten/duurzame_systeeminnovatie/verkenningen_en_scenarios/kansen_voor_nanotechnolog/index.xml ESA Discovery and competitiveness: the keywords in Europe’s policies and programmes for space (2005) www.esa.int/esaCP/index.html ESTP, “Strategic Research Agenda”, European Space Technology Platform, Brussels, 22/06/06 http://www.estp-space.eu/ Eureka 2006, 26 (6), 24. European Commission, “Commission Communication on European Space Policy – Preliminary Elements COM (2005)208”, European Commission, Brussels, 23 May 2005, http://ec.europa.eu/comm/space/news/docs/esp_23_5_com_2005_208_final_en.pdf (last accessed 26-10-06)

141

European Commission, “Commission Communication on a thematic strategy on air pollution – COM (2005)446”, European Commission, Brussels, 21 September 2005, http://ec.europa.eu/environment/air/cafe/index.htm (last accessed 28-09-06) European Commission Communication, “Reducing the Climate change impact of aviation - COM (2005)459 final”, 27 September 2005, http://ec.europa.eu/environment/climat/aviation_en.htm (last accessed 16-11-06) European Commission, “Press release Space Policy: EU and Russia join forces and sign cooperation agreement”, European Commission, Brussels, 10 March 2006, http://www.europa.eu.int/rapid/pressReleasesAction.do?reference=IP/06/297&format=HTML&aged=0&language=EN&guiLanguage=en (last accessed 25-10-06) European Commission, “Mid-term review of the Transport White Paper, Keep Europe Moving – Sustainable Mobility for our Continent”, European Commission, Brussels, 22 June 2006, http://ec.europa.eu/transport/transport_policy_review/index_en.htm (last accessed 28-09-06) European Commission Communication: “Action Plan for Energy Efficiency: Realising the Potential – COM(2006)545”, European Commission, Brussels, 19 October 2006, http://ec.europa.eu/energy/action_plan_energy_efficiency/index_en.htm (last accessed 16-11-06) European Commission, FP7 factsheets http://ec.europa.eu/research/fp7/understanding/index.html FhG-IFAM annual report 2004, http://www.ifam.fraunhofer.de/jahresberichte/jb04/jb2004_de.pdf

Edward P. Flinn, “Nanosensors to monitor Space Radiation Exposure”, in Aerospace America, vol 43 (2005), issue 1, p 14 Forbes: “Russian government agrees 12.5 billion euro 10-yr space programme”, 2005, www.forbes.com/finance/feeds/afx/2005/07/15/afx2141304.html Freedonia, “Nanocomposites”, a new study from the Freedonia Group, Inc., Cleveland, USA, May, 2006. Michael Garner, INTEL, Santa Clara, Dan Herr, Semiconductor Research Corporation, Durham, NC, Donald B. Anthony, Council for Chemical

142

Research, Washington DC et al, “Toward Predictive NanoMaterial Design”, NIST, USA, online publication at http://www.mel.nist.gov/nanopdfs/TowardPredictivegarner.pdf (last accessed 16-11-06) Gautsch, S. (2000): „Development of an AFM Microsystems for Nanoscience in Interplanetary Research“ 3rd round table on Micro/Nanotechnologies for Space, 15-17 May 2000, ESTEC Noordwijk Nl, ESAWPP-174, pp. 173-178 Jerome C. Glenn and Theodore J. Gordon, “2005 state of the future”, American Council for the United Nations University, Millennium project, 2005, http://www.acunu.org/millennium/ Globus Al, 1999. Molecular Nanotechnology in aerospace: 1999. Veridian MRJ Technology solutions. Hella, 2006, Project „Basic research for the application of transparent conductive layer systems as de-icing layer for LED headlights“, http://oas2.ip.kp.dlr.de/foekat/foekat/einzeldarstellung?p_fkz=13N9028

Hidden G.; Boudou L.; Martinez-Vega J.; Remaury S.; Nabarra P., Polymer Engineering and Science 2006, 46 (8), 1079-1084. High Performance Plastics June 2006, 4; ibid, 3; High Performance Plastics May 2006, 1. Woong-ki Hong et al., “Radiation hardness of the electrical properties of carbon nanotube network field effect transistors under high-energy proton radiation”, Institute of Physics publishing, 2006, Nanotechnology 17, 5675-5680 http://ej.iop.org/links/rImsCRa0Q/pqm_cQyf2xGGXDebav5vpA/nano6_22_023.pdf IATA outlook on the financial status of the international aviation industry (www.iata.org/whatwedo/economics/index.htm) IMI, “The Industrial Materials Institute (IMI) of the National Research Council of Canada”. Institute of Nanotechnology. 2006. Roadmaps for Nanotechnology in Energy: http://www.nanoroadmap.it/roadmaps/NRM_Energy.pdf Neil A. Ives et al., “Nanoscale Three-Dimensional Imaging: an innovative tool for failure analysis, Crosslink Fall 2005, p 16-17

143

IWGN (1999): Nanotechnology Research Directions, Interagency Working Group on Nano Science, Engineering, and Technology (IWGN) of the NSTC, Workshop report 1999, S. 73 Johnson M.A., Tompkins S.D., Truszkowski W.F., 1999. Information systems for nanosatellite constellations. NASA. 1999. Available from: http://agents.gsfc.nasa.gov/papers/pdf/isnc.pdf Wei Kao, Russell Lipeles and Woonsup Park, “Lighter, Stronger, Better: Significant trends in material research”, Crosslink Fall 2006, p 4-7 Rocky Khullar et al., “Picosatellite missions and applications”, the Aerospace Corporation, 2004 Katrin and Harald Kneipp, “Novel nanosensors for health monitoring and environmental control based on surface-enhanced Raman scattering (SERS)”, Concept paper 12, CANEUS, 2006, www.caneus.org Katrin Kneipp et al, “Miniature High performance MNT/IOSPEC Infrared diagnostic system for the remote monitoring of astronaut health”, Concept paper 12a, CANEUS, 2006, www.caneus.org V. Kostopoulos et al., “Nano-modified fibre reinforced composites: a way toward the development of new materials for space applications”, 2005 https://escies.org/GetFile?rsrcid=1690 Kovar R.F.; Yost E.; Orbey N.; Ocnos G., SAMPE '06: Creating New Opportunities for The World Economy: Volume 51. Proceedings of a conference held in Long Beach, Ca., 30th April-4th May 2006. Editor(s): SAMPE Covina, Ca., SAMPE International Business Office, 2006, Paper 2. S. Kraft, “Highly integrated payloads architectures and instrumentain for future planetary mission”, Cosine Research B.V, 2005 Kenneth Kuo et. al, MRS fall meeting 2003, “Potential Usage of Energetic Nano-sized Powders for Combustion and Rocket Propulsion”, http://www.mrs.org/s_mrs/sec_subscribe.asp?CID=2642&DID=115851&action=detail

Ben Lannotta, “Nanotubes lift hopes for space elevator”, Aerospace America p31-35, 2006 http://www.aiaa.org/aerospace/images/articleimages/pdf/AA_Mar06_IAN.pdf A. Luque and A. Martí, “Increasing the Efficiency of Ideal Solar Cells by Photon Induced Transitions at Intermediate Level”, Physical review, 26, 5014, 1997

144

Lux Research Inc, “Nanomaterials: Nanostructured Metals”, in the Nanotech report 4, 2006, http://www.luxresearchinc.com/Nanostructured_Metals.pdf Mankins, J.C. 2003. The Promise and challenge of Space solar power. NASA. Available from: http://www.kurasc.kyoto-u.ac.jp/jusps/KA-2.pdf CCN Matthews, “Government of Canada invests in Aerospace Nanotechnology”, Ottawa, Ontario, 27 June 2005, http://www.ccnmatthews.com/news/releases/show.jsp?action=showRelease&actionFor=546755 Andrew Maynard et al, “Safe handling of nanotechnology”, in Nature Vol. 444, 16 November 2006, http://www.nature.com/materials/nanozone/news/061116/journal/444267a.html Meyya Meyyappan & Minoo Dastoor, “Nanotechnology in Space Exploration”, Report of the National Nanotechnology Initiative Workshop, August 24-26, 2004, NSTC-NSET, NASA, 2006, http://www.nano.gov/html/res/pubs.html W I Milne. 2003. Electronic devices from diamond-like carbon. Semicond. Sci. Technol. 18 S81-S85 Moniruzzaman M.; Winey K.I., Macromolecules 2006, 39 (16), 5194-5205. John Mulcair, “Fantastic plastic, cool carbon”, in Flight Safety Australia, November-December 2003, p 54-55 Nanoforum report, 2003, “Nanotechnology helps solve the world’s energy problems”, http://www.nanoforum.org/dateien/temp/EnergyReport140104.pdf?20042005174017 Nano Letters, “Temperature-Activated Interfacial Friction Damping in Carbon Nanotube Polymer Composites,” Nano Letters 6, 219-223 (2006). NANOMAG, European Commission 2003, “Nanocoatings lighten environmental burden of mobility”, http://ec.europa.eu/research/industrial_technologies/articles/article_346_en.html

David H. Napier, 2005 Year-End Review and 2006 Forecast - an Analysis, Aerospace Research Center (Aerospace Industries Association) (www.aia-aerospace.org/stats/yr_ender/yrendr2005_text.pdf)

145

NanoroadSME, SME-Survey Aeronautics, http://www.nanoroad.net/download/is_as.pdf

Nanosonic. 2004. Researchers synthesize a novel rubber material. Available at: http://www.nanosonic.com/publicity/pr4.html NASA Aerospace Technology News, “Fuell Cells for Launch Vehicles?”, 2001, http://www.aero-space.nasa.gov NASA Ames Research Centre, “Ultrasensitive label-free electronics biochips based on Carbon Nanotube nanoelectrode arrays” http://www.nasa.gov/centers/ames/research/technology-onepagers/ultrasensitive_biochip.html NASA Glenn Research Centre, “Quantum Dots Solar Cells” http://powerweb.grc.nasa.gov/pvsee/programs/thinfilm/tfg_nano.html NASA White Paper 2001, “Aeronautics Vision for the 21St Century, http://www.ewh.ieee.org/soc/aes/Blueprint.doc

NASA,2000. Available from: http://science.nasa.gov/headlines/y2000/ast07sep_1.htm

NASA, Jet Propulsion Laboratory. Press release, 2000: http://www.jpl.nasa.gov/releases/2000/lasersail.html

Nature Materials, “Nanoparticle networks reduce the flammability of polymer nanocomposites,”Nature Materials 4, 928–933 (2005).

Navy, 2006, “Nano-Phase Exothermically Formed Perovskite Ceramic Materials for TBC CMAS Penetration Protection”, http://www.navysbir.com/06_1/85.htm

Flavio Noca et al, “Nanocarpets for trapping microscopic particles”, NASA tech briefs, 2004 Sarah E. O’Donnell, Impact of nanomaterials in airframes on commercial aviation, American Institute of Aeronautics and Astronautics, The MITRE Corporation Center for Advanced Aviation System Development (CAASD), McLean, Virginia 22102. Genevieve Oger, “Aerospace market still struggling to take off”, SmallTimes, November 2006, www.smalltimes.com/articles/stm_print_screen_cfm?ARTICLE_ID=276888

Ohio Aerospace Institute. 2005. Available at: http://www.oai.org/about/people/research.html

146

Physorg.com, February 20, 2006, “Nano World: Nano for self-healing material”, http://www.physorg.com/news11000.html

Physorg.com, “NASA researchers customize lab-on-a-chip technology to protect future space explorers and detect life forms on Mars”, 2004, http://www.physorg.com/news146.html

Pimprikar, M., Naghshin, R., Srivastava, D. 2003. Role of Nanotechnology in Future Space Missions. Presentation at ESA-ESTEC.

S. Plano, “Sustainable Production: The Role of Nanotechnologies”, http://ec.europa.eu/research/growth/pdf/nanotechnology02-conference/presspacklyngby-4b-nanomag_ohs_final300902.pdf

P.Poizot et al., “Nano-sized transistion-metal oxides as negative-electrode materials for lithium-ion batteries”, Nature 407 p496-499, 2000

Alan P. Pritchard, “Harnessing the potential of micro and nano technology for the aerospace industry - examples at BAE Systems (UK), http://pdf.aiaa.org/preview/CDReadyMCAN2004_1085/PV2004_6738.pdf

Pröbstle, H., Schnitt, C, Fricke, J. (2002) „Button Cell Supercapacitors with monolithic carbon aerogel electrode“; Journal of Power Sources, 105 Mihail Roco and William Bainbridge, “Societal Implications of Nanoscience and Nanotechnology”, NSF, Arlington, VA, 2001, http://www.wtec.org/loyola/nano/NSET.Societal.Implications/ Rossoni, P.; Panetta, P. (1999): Developments in Nano-Satellite Structural Subsystem Design at NASAGSFC“13th AIAA/USU Conference on Small Satellites, 23-26. 8.1999 Ren Qinghai, European Patent Office, 2002, Speeding up nano paint and its application, http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=CN1382751&F=0 RAPRA Polymer Bulletin “Aerospace Applications”; http://www.rapra.net Riegler B.; Kaelani F.; Long D.A., SAMPE '06: Creating New Opportunities for The World Economy: Volume 51. Proceedings of a conference held in Long Beach, Ca., 30th April-4th May 2006. Editor(s): SAMPE Covina, Ca., SAMPE International Business Office, 2006, Paper 3. Tim Robbins, “The anti-jet lag plane“, Guardian, July 23, 2006, http://www.compositesnews.com/cni.asp?articleID=11516

147

Alan J. Russell et al., “Self-Assembly of Biocidal Nanotubes from a Single-Chain Diacetylene Amine Salt”, Journal of the American Chemical Society, 126, 2004 Russian minister, Aircraft construction corp. to be formed by April, 2006 http://en.rian.ru/russia/20061020/54983502.html Salek M.H.; Hoa S.V., SAMPE '05: New Horizons for Materials and Processing Technologies. Proceedings of a conference held in Long Beach, Ca., 1st-5th May 2005. Editor(s): SAMPE Covina, Ca., SAMPE International Business Office, 2005, Paper 229.

Jennifer L. Sample et al., “Nanotechnology and advanced materials for space applications”, American Institute for Aeronautics and Astronautics, 2005 – 6691

Science Daily, 2005: http://www.sciencedaily.com/releases/2005/07/050727062335.htm

M. Shaffer, I. A. Kinloch, Prospects for nanotube and nanofibre composites, Composites Science and Technology 64 (2004) 2281-2282. Guo Shuihu, European Patent Office, 2003, “Method for preparing modified nano boron oxide”, http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=CN1438176&F=0 Simonis, F., and Schiltbuizen. Nanotechnology – innovation opportunities for tomorrows defense. Report by Future Technology Centre. Available from: http://www.futuretechnologycenter.nl/downloads/nanobook.pdf Smalltimes, “NASA to put sensor in latest black boxes”, 2005 http://smalltimes.com/Articles/Article_Display.cfm?ARTICLE_ID=270014&p=109 Space Daily: http://www.spacedaily.com/reports/Nano_World_Carbon_Nanotube_Capacitors.html Alexander Star et al., “Gas sensor Array Based on Metal-Decorated Carbon Nanotubes”, Nanomix, 2006 http://pubs.acs.org/cgi-bin/article.cgi/jpcbfk/2006/110/i42/pdf/jp064371z.pdf STAR21: Strategic Aerospace Review for the 21st Century, www.ec.europa.eu/enterprise/aerospace/report_star21_screen.pdf

148

D. Stilwell, “Life Sciences Technology Needs in Nano/micro Tehnologies”, 4th International Conference on Integrated Nano/Microtechnology for Space and Biomedical Applications, 2001

Mark D. Taczak: “A Brief Review of Nanomaterials for aerospace applications: Carbon Nanotube-reinforced Polymer Composites”, MITRE Nanosystems Group, Virginia, May 2006.

Ken Teo et al. “Microwave devices: Carbon nanotubes as cold cathode”, Nature 437 968, 2005 http://www.nature.com/nature/journal/v437/n706/full/437968a.html Ann M. Thayer, “Chance of a Lifetime”, in C&EN, 1 May 2006, Vol. 84, No. 18, pp 10-18, http://pubs.acs.org/cen/coverstory/84/8418nanotechnology.html E.T. Thostenson, T-W Chou, “Carbon Nanotube Networks: Sensing of Distributed Strain and Damage for Life Prediction and Self Healing”, in Advanced Materials Early View, 2 October 2006, http://www3.interscience.wiley.com/cgi-bin/abstract/113385715/ABSTRACT John Toon, “Mimicking Nature creates self cleaning coatings”, physorg, 2006 http://www.physorg.com/news79957161.html Torres, J, Ferrer, C., Paris, L. 1996. Small satellite systems and services: Proceedings of the third international symposium, Annecy, France. 24-28 June, 1996. Available from: http://md1.csa.com/partners/viewrecord.php?requester=gs&collection=TRD&recid=A9723878AH&q=nanosatellite+%2B+nanotechnology&uid=789933632&setcookie=yes Többen, H.H. (1999):In-Flight Exposure Experiment SESAM“, Proceedings of the 2nd European Symposium on the Utilization of the International Space Station, ESTEC, Noordwijk, The Netherlands, 16.-18. November 1998; ESA SP-433, Feb 1999 pp. 135-142 TPC, Technology Partnerships Canada, June 27, 2005, “Government of Canada Invests in Aerospace Nanotechnology“, http://www.ccnmatthews.com/news/releases/show.jsp?action=showRelease&actionFor=546755 Piotr Tucholka, “Major challenges for environmental studies”, paper presented at CANEUS conference Canada, 26-30 August 2002, http://www.nexus-mems.com/documents/CANEUS_workshop.pdf

149

UNESCO, “The ethics of outer space; Policy document”, UNESCO World Commission on the Ethics of Scientific Knowledge and Technology, June 2004, http://portal.unesco.org/shs/en/ev.php-URL_ID=6489&URL_DO=DO_TOPIC&URL_SECTION=201.html (last accessed 11-10-06) University of Bristol. Available from: http://www.aer.bris.ac.uk/research/morphing/morph-intro.html Harry Valentine, Airliners.net, October 9, 2006, “Alternatives in Aviation after Peak Oil”, www.airliners.net/articles/read.main?id=98 VDI Technology Centre, “Applications of Nanotechnology in Space Developments and Systems”, 2003 Anthony A. Waitz, “MEMS based vibration sensing and analysis system to predict structural failures in aircraft”, Concept paper 11, CANEUS, 2006, www.caneus.org White House, “US National Space Policy”, Washington DC, 31 August 2006, published online at http://www.ostp.gov/html/US%20National%20Space%20Policy.pdf (last accessed 25-10-06) Wincheski, B., Namkung, M. (2000): „Development and Testing of Iron Polyimide Nanocomposites for Magnetic Field Sensing Applications“ Proceedings of Nanospace 2000, 3rd International Conference on Integrated Nano/Microtechnology for Space Applications, Galveston, Texas, 23-28.01.2000 Piet Woelcken, Clemens Bockenheimer, Henrik Rösner, “Nanotechnology for future Airbus airframes”, paper presented at Nanosolutions 2006, 28-30 November, Expo XXI, Cologne, http://www.nanosolutions-cologne.de/ Detlev Wolter, “Common security in outer space and international law,” United Nations Publications, 2006, http://www.unidir.org/bdd/fiche-ouvrage.php?ref_ouvrage=92-9045-177-7-en Yablonovitch, E. (2002): Halbleiter für Lichtstrahlen, Spektrum der Wissenschaft 4/2002, S. 66-72 Zweck, Dr Dr A., Luther, Dr. W. 2003. Application of Nanotechnology in Space development and systems. VDI Technology Centre Links Scratch: www.aero-scratch.net/

150

AeroSME: www.aerosme.com/ Aerospace Corporation: http://www.aero.org/ AFRL Horizons: http://www.afrlhorizons.com American Institute of Aeronautics and Astronautics (AIAA) http://www.aiaa.org/ EADS Space: www.space.eads.net/company ESA MNT roundtables: https://escies.org/servlet/xslt/?xml=/public/conferences/mnt5/index.xml ESA: www.esa.int/SPECIALS/Technology_Transfer/SEMZ5TRMD6E_0.html NanoroadSME: roadmap on nanomaterials for aeronautics, www.nanoroad.net > downloads. CANEUS: International Development of MNT for Aerospace applications, www.caneus.org (projects and bi-annual conferences) ACARE4Europe: Advisory Council for Aeronautics Research in Europe: http://www.acare4europe.com/ ECARE-SME: www.ecare-sme.org/plus/index.asp European Space Technology Platform: http://www.estp-space.eu/ The Integral Satcom Initiative: http://www.isi-initiative.eu.org/ European Aviation Safety Agency, EASA: http://www.easa.eu.int/home/index.html European Centre for Space Law: http://www.esa.int/SPECIALS/ECSL/index.html United Nations Office for Outer Space Affairs: http://www.unoosa.org/oosa/index.html European Commission Space Policy: http://ec.europa.eu/enterprise/space/index_en.html European Cooperation on Space Standardisation: http://www.ecss.nl/ ICAO: International Civil Aviation Organisation: http://www.icao.int/ NASA www.nasa.gov

151

NASA Nanotechnology R&D: http://www.ipt.arc.nasa.gov/nano_rd.html NNI: http://www.nano.gov/nni_space_exploration_rpt.pdf Integran webpage, http://www.integran.com/applications/aerospace.htm

Nanovic webpage, http://www.nanovic.com.au/?a=industry_focus.Aerospace&p=61

Nanovobs: www.navobs.com/

JAXA: http://www.jaxa.jp/index_e.html ISRO: www.isro.org

Nanocompositech: http://www.nanocompositech.com/carbon-nanotubes-nanocomposites.htm Space.com: www.space.com Ohio Nanosummit: http://www.ohionanosummit.net