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A Geophysical Mission to Venus: Results of the Alpbach Summer School 2014 R.J. Koopmans1 , A. Białek2 , A. Donohoe3 , M. Fernández Jiménez4 , B. Frasl5 , A. Gurciullo6 , A. Kleinschneider7, A. Losiak8, T. Mannel9 , I. Muñoz Elorza10, D. Nilsson11, M. Oliveira12, P. M. SørensenClark13, R. Timoney14, I. van Zelst15

1FOTEC Forschungs und Technologietransfer GmbH, Wiener Neustadt, Austria, 2Space Research Centre Polish Academy of Science, Warsaw, Poland, 3Maynooth University, Ireland, 4Universidad Carlos III, Madrid, Spain 4, 5Zentralanstalt für Meteorologie und Geodynamik, Vienna, Austria, 6Royal Institute of Technology, Stockholm, Sweden, 7Delft University of Technology, Delft, the Netherlands, 8Institute of Geological Sciences, Polish Academy of Science, Wroclaw, Poland, 9 Institute for Space Research, Austrian Academy of Sciences, 10HE Space Operations GmbH, Bremen,

Germany, 11Luleå University of Technology, Luleå, Sweden, 12Instituto Superior Técnico, Lisbon, Portugal, 13University of Oslo, Oslo, Norway, 14University of Glasgow, Glasgow, United Kingdom, 15Department of Earth Sciences, Utrecht University, the Netherlands

Why Venus? Venus has been investigated by only five dedicated mission programs since the beginning

of space flight. This relatively low level of interest is remarkable when considering that mass and radius of Venus are very similar to Earth's, while at the same time characteristics such as spin rate, atmospheric composition, pressure and temperature, make Venus a very different, uninhabitable world. The underlying causes of these differences are not well understood. The importance of this scientific topic has been recognized in ESA’s and NASA’s strategic plans: Cosmic Vision (ESA, 2005) and Visions and Voyages (NRC, 2011).

What we will do? The aim of the Hesperos mission is to investigate why Earth and Venus evolved differently:

1. Does Venus have a similar internal structure and composition as Earth? This will help us to constrain the conditions necessary for emergence of life on our planet as well as on others (including exoplanets). The comparison of Venus and Earth internal structures could provide some insight in the evolution (and differentiation) of a planet. While the internal structure of Earth is relatively well known due to seismological studies (Dziewonski and Anderson 1981), the interior of Venus is not well constrained. 2. Is Venus tectonically active and on what time scale? Plate tectonics is probably one of the necessary conditions for life (Valencia et al. 2007). It recycles chemicals necessary for life and increases atmospheric pressure by degassing. Additionally, it is probably required for formation of longlasting, strong magnetic field on terrestrial planets. As a result, plate tectonics creates diverse environments where organisms can live. Mercury, Mars and Moon were tectonically active in the past, but it was most likely not related to plate tectonics (Harrison 2000). The only planet that may be still volcanically and tectonically active in plate-tectonics style is Venus.

How will we accomplish goals? How much will it cost?

~2100 M€ ESA’s L-class mission

ESA (2005) Cosmic Vision, Space Science for Europe. ESA Publication. NRC (2011) Vision and Voyages for Planetary Science in the Decade 2013-2022. National Academies Press Washington A. M. Dziewonski, D. L. Anderson, (1981) Preliminary reference Earth model, Physics of the Earth and Planetary Interiors 25: 297-356. D. Valencia, R. J. O'Connell, D. D. Sasselov, I (2007) nevitability of plate tectonics on super-earths, Astrophysical Journal 670: L45-L48. C. Harrison (2000) Questions about Magnetic Lineations in the Ancient Crust of Mars, Science: 547.

Alpbach Summer School The Alpbach Summer School, held annually

since 1975, is a two week training program organized by FFG and co-sponsored by the European Space Agency and associated national space authorities. Its purpose is to advance the training and working experience of European graduates, post-graduate students, young scientists and engineers in order to prepare them for careers in space science and industry. Participants grouped in four teams compete to design the best space mission and are judged by an independent jury of experts. The best ideas devised during the summer school are further developed during a one week Post-Alpbach Program. This poster presents results of the 2014 Post-Alpbach workshop.

This year the Alpbach Summer School will be held from 14 to 23 July 2015, and will focus on “Quantum Physics and Fundamental Physics in Space". Deadline for application is on 31 March 2015.

Objectives Questions Detailed questions Observables Payload

1. Does Venus have a similar internal structure and composition as Earth?

1.1 Core 1.1.1. What is the composition of the core (density, mass)?

Spin rate, J2-Effect, Moment of inertia, Seismic waves

Synthetic aperture radar (O) Sounding device (B)

1.1.2. Is the core liquid of solid?

Magnetic field, Seismic waves

Magnetometer (B), Sounding device (B)

1.1.3. What is the dynamics of the core?

Magnetic field, Ionosphere holes

Magnetometer (B)

1.2 Mantle 1.2.1. What is the composition, density and the mass of the mantle?

Seismic waves Sounding device (B)

1.2.2. Is the mantle liquid of solid?

Spin rate, J2-effect, Moment of inertia, Seismic waves

Synthetic aperture radar (O), Sounding device (B)

1.2.3. What is the dynamics of the mantle?

Magnetic field, Gravity waves, Volcanism

Magnetometer (B), Synthetic aperture radar (O)

1.2.4. What is the evolution of the mantle?

Noble gas isotopes in atm. Surface emissivity maps

Mass spectrometer (B), IR + UV spectrometer (O)

1.2.5 What is the mantle’s interaction with the surface?

Volcanism, Emissivity maps Topography, Plate movement, Crust Thickness

Synthetic aperture radar (O), IR + UV spectrometer (O), Gradiometer (O)

2. Is Venus tectonically active and on what time scale?

2.1. Active volcanism

2.1.1. What is the distribution of active volcanoes?

Heat signatures , Imaging/ topography, Gases in the atmosphere, Gravity changes , Acoustic waves

IR + UV spectrometer + IR camera (O), Synthetic aperture radar (O), Gradiometer (O), Sounding device (B)

2.1.2. What is the activity of the volcanoes (level, type, scale)?

Heat signatures , Imaging/ topography, Gases in the atmosphere, Dust in the atmosphere, Gravity changes , Acoustic waves

IR + UV spectrometer + IR camera (O), Synthetic aperture radar (O), Nephelometer (B), Gradiometer (O), Sounding device (B)

2.1.3. What is the variability of the volcanic gases in the atm.?

Abundance , Isotopic composition, Spatial variation

Mass spectrometer (B) IR + UV spectrometer + IR camera (O)

2.2. Plate movement

2.2.1. Does plate movement exist (characteristics)?

Surface elevation changes Magnetic striping, deep gravity anomalies

Synthetic aperture radar (O), Magnetometer (B), Gradiometer (O)

2.2.2. What is the speed and direction of plate movement?

Long-term topography changes

Synthetic aperture radar (O)

2.2.3. Is there evidence of past activity?

Magnetic striping, Imaging/ topography

Magnetometer (B), Synthetic aperture radar (O)

2.2.4 Is there seismic activity?

Acoustic waves in atm. Sounding device (B)

Post-Alpbach 2014 Group

Nephelometer Magnetometer Mass Spectrometer Sounding + Meteo

Altitude – 250 km

Eccentricity - 0

Period - 92 min

Inclination – 85º

Table 1. Scientific objectives, questions, observables and related payload of the Hesperos mission (O) stands for an

instrument on the orbiter, (B) for an instrument in the balloon.

Gradiometer SAR IR+UV spectrometer IR Camera

Balloon

Orbiter

Important issues:

• Communication balloon-orbiter balloon phase during

eccentric orbit

• Measurements on different altitudes two phase balloon

• Magnetometer precision and accuracy long beam

below gondola

Important issues: • SAR requires high datarate data storage, streaming or/and optical link. - Thermal requirements combined passive & active control systems. - Long term measurements by SAR 5 year mission.

Variation in altitude of the

Balloon. Red dots indicate

sampling points for mass

spectrometer.

Mission element Mass [kg]

Balloon total 213.1

Orbiter total 1430.4

S/C dry mass +

20% margin 1914.7

Propellant mass 2023.7

Launch mass 3938.4

Acknowledgement: The authors would like to express their gratitude to ESA and FFG for organizing the Alpbach Summer School as well as the post-Alpbach week. We would also like to thank our supervisors Gunter Kargl and Olivier Baur from the Space Research Institute of the Austrian Academy of Sciences, Richard Ghail from Imperial College London and Manuela Unterberger from the Technical University of Graz for their valuable advice and enthusiasm.