NASA Environmental Control and Life Support Technology

ICES-2020-200

NASA Environmental Control and Life Support Technology

Development and Maturation for Exploration: 2019 to 2020

Overview

Walter F. Schneider1 and Jay L. Perry2

NASA Marshall Space Flight Center, Huntsville, AL, 35812

James L. Broyan3, Ariel V. Macatangay4, Melissa K. McKinley5, and Caitlin E. Meyer 6

NASA Johnson Space Center, Houston, TX 77058

Andrew C. Owens7

NASA Langley Research Center, Hampton, VA 23681

Nikzad Toomarian8

NASA Jet Propulsion Laboratory, Pasadena, CA 91011

and

Robyn L. Gatens9

NASA Headquarters, Washington, D.C. 20546

During 2019 and 2020, NASA’s Environmental Control and Life Support (ECLS)

technology development projects have taken vital steps toward establishing readiness for the

next generation of human space exploration missions. Technology demonstration systems

from last year have been operated on the International Space Station (ISS) and others have

been launched. Progress has been made toward future technology demonstrations. Facility

and hardware development have been initiated for ground testing that strategically

complements technology demonstration aboard the International Space Station (ISS) and

some ground testing has been initiated. Reliability studies are being conducted to define

requirements for flight demonstration and ground testing as well as inform other investments

to support exploration missions. These efforts support NASA-led missions beyond LEO which

include Gateway, lunar surface, Mars transportation, and Mars surface mission architectures.

This paper provides an overview of the current ECLS strategic planning and roadmap as well

as a synopsis of key technology and maturation project tasks that occurred in 2019 and early

2020 to support the strategic needs. Plans for the remainder of 2020 and subsequent years are

also described.

1 Advanced Exploration Systems Life Support Systems Project Manager, Human Exploration Development and

Operations, Marshall Space Flight Center, Mail Stop HP30. 2 Aerospace Engineer, ECLS Systems Development Branch, Space Systems Department, Mail Stop ES62. 3 ECLS Systems Capability Deputy Lead, Crew and Thermal Systems Division, Mail Stop EC7. 4 Scientist, Human Systems Engineering and Development Division, Mail Stop SF2. 5 Advanced Exploration Systems Logistics Reduction Project Manager, Crew and Thermal Systems Division, Mail

Stop EC7. 6 Advanced Exploration Systems Life Support Systems Deputy Project Manager, Crew and Thermal Systems

Division, Mail Stop EC3. 7 Aerospace Engineer, Space Mission Analysis Branch, Mail Stop 462. 8 Project Manager, Environmental Monitoring Systems, Instruments Division, Jet Propulsion Lab, Mail Stop 321-520. 9 ECLS Systems Capability Lead, NASA Headquarters, Mail Stop CJ000.

International Conference on Environmental Systems

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Nomenclature

AC-TSAC = Air Cooled Temperature Swing Adsorption Compressor

AES = Advanced Exploration Systems

AGA = Anomaly Gas Analyzer

AnMBR = Anaerobic Membrane Reactor

AOGA = Advanced Oxygen Generation Assembly

AR = atmosphere revitalization

BFE = bacteria filter element

BPA = Brine Processor Assembly

BWP = biological water processor

CDM = Carbon Dioxide Monitor

CDR = critical design review

CFU = colony forming unit

CHP = Crew Health and Performance

CMS = Chip Monitoring System

COTS = commercial-off-the-shelf

CSA-CP = Compound Specific Analyzer-Combustion Products

DC = direct current

DFS = dual fan separator

DGA = diglycol amine

DMSD = dimethylsilanediol

DNA = deoxyribonucleic acid

ECLS = Environmental Control and Life Support

ECLSS = Environmental Control and Life Support System

EDU = engineering development unit

EMI = electromagnetic interference

HEPA = high efficiency particulate arrestance

HMC = Heat Melt Compactor

HRHR = high risk, high reward

ISS = International Space Station

JPL = Jet Propulsion Laboratory

JSC = Johnson Space Center

KSC = Kennedy Space Center

LEO = Low Earth Orbit

LR = Logistics Reduction

LSS = Life Support Systems

MABR = Membrane Aerated Biological Reactor

MCA = Major Constituent Analyzer

MFB = Multifiltration Bed

MOF = metal-organic framework

MSFC = Marshall Space Flight Center

NASA = National Aeronautics and Space Administration

OGA = Oxygen Generation Assembly

PCPA = Pressure Control Pump Assembly

PDR = preliminary design review

PMBR = Photo-Membrane Bioreactor

POM = Portable Oxygen Monitor

PPA = Plasma Pyrolysis Assembly

SBIR = Small Business Innovative Research

SCLT = System Capability Leadership Team

SOA = state-of-the-art

TCC = trace contaminant control

TCPS = Trash Compaction and Processing System

TEC = Toxicology and Environmental Chemistry


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TLS = tunable laser spectrometer

TOC = total organic carbon

TOCA = Total Organic Carbon Analyzer

TVS = temperature-vacuum swing

UPA = Urine Processor Assembly

USF = University of South Florida

UV = ultraviolet

UWMS = Universal Waste Management System

VMS = volatile methyl siloxane

VOC = volatile organic compound

WRS = water recovery system

WSTF = White Sands Test Facility

I. Introduction

OR all crewed space exploration missions Environmental Control and Life Support System (ECLSS) equipment,

spares, and consumables represent the largest non-structure-propellant mass allocation. NASA exploration

architectures and missions have evolved over the past year as the Agency’s Artemis plans have matured. Early Artemis

missions will return to the moon with open loop ECLSS due the initial short lunar surface duration missions of six

days. Gateway will support Artemis missions for both the initial short sorties and sustained lunar surface missions

over a wide range of lunar latitudes using partially-closed ECLSS. Gateway also provides access to the unique deep

space radiation environment, important for system controller electronics and some Crew Health Performance (CHP)

systems, which will be representative of Mars transit. Orion and the Gateway support initial and sustained-lunar

Artemis missions and will initially use primarily open loop ECLSS. Sustained lunar and Mars surface missions

envision partially-closed ECLSS that are adapted for partial gravity.

Figure 1 illustrates the mission stepping stones to Mars and how the ECLSS will need to evolve. The International

Space Station (ISS) is utilized as a testbed for validating technology selections along with ground testing and ground

analogs to establish reliability predictions and identify areas for improvement.1

Transit missions to Mars will require mostly closed ECLSS to significantly reduce water and oxygen consumable

mass, and the Gateway architecture will evolve to include this Mars transit capability. Recent ECLSS-CHP integrated

analysis has identified that the water content of launched food is a strong driver to the necessary level of ECLSS

closure for a Mars transit mission. The lowest overall system mass is achieved by an ECLS oxygen system closure of

>75% coupled with an average food water content of <40%. Reliable space flight hardware is always important but

it becomes paramount for Mars transit missions where all spares must be launched with the transit vehicle. For this

reason, long-duration testing on the ISS and follow-on LEO platforms is critical to obtain the necessary time on system

microgravity

performance and support

reliability estimates. It is

important that each of

these missions be used to

validate technology for

the future missions.

Technology

development is guided by

the Agency’s System

Capability Leadership

Team (SCLT) for

Environmental Control

and Life Support Systems

(ECLSS) which has

expanded to include

Crew Health and

Performance (CHP). The

ECLSS-CHP SCLT

merger allows closer

F

Figure 1. Evolving Exploration ECLSS-CHP systems for sustainable human

exploration.


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coordination of technologies and interdependency analysis. This paper describes the progress on ECLS technology

development during 2019 and 2020 and some interrelationships to CHP (exercise2 and extravehicular activity3,4).

Future conference papers will include a companion CHP paper with greater details.

II. Exploration Gaps

Understanding component and system reliability is critical because their cumulative mass is significant. Using ISS

for addressing microgravity (µg) sensitivities and other representative environmental parameters in combination with

endurance ground testing is essential to establish highly reliable ECLS and bring down departure mass. Gaps are

defined as the difference between the state-of the-art and future mission needs. Capability gaps can encompass

knowledge, technology, hardware development, and architecture. This past year, ECLSS-CHP gaps were reassessed

against a range of potential lunar and

Mars exploration mission

architectures. Approximately 60

ECLSS-CHP gaps were identified

representing the largest single set of

capability challenges for exploration

as illustrated by Fig. 2. Details for

these gaps by function are included in

subsequent sections of this paper.

Technology roadmaps are used to

layout gap closing steps and have

been previously reported.5 These

roadmaps and the gaps they are

bridging map to Artemis, Gateway,

lunar surface, and Mars transit and

surface exploration initiatives and show how earlier exploration mission phases support later longer duration missions

where system endurance is substantially more challenging. Identifying how earlier exploration missions, designated

in Fig. 3 as “first enabled platforms”, allow technology validation to support later exploration missions. This is an

important concept in which earlier missions incorporate exploration-forward requirements and hardware interface

scars for all gaps to be closed via flight demonstration before they are applied to more challenging missions. Figure 3

indicates the need for continued testing in low Earth orbit (LEO) aboard ISS, ground testing, and analog activity to

enable technologies for multiple platforms.

Figure 3. Exploration Capability Gap closure, ‘validation platform’, support of later exploration missions,

‘first enabled platforms’.

Figure 2. ECLSS-CHP (Human Health, Life Support and Habitation

Systems) gaps by platform enabled


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III. Atmosphere Revitalization

This section summarizes accomplishments in the subsystem architecture, oxygen generation and recovery, carbon

dioxide removal, and trace contaminant and particulate matter control technical areas.

Oxygen Generation and Recovery

Progress in the oxygen generation and recovery technical area included work on an Advanced Oxygen Generation

Assembly (AOGA), high pressure oxygen generation technology, methane plasma pyrolysis assembly (PPA)

technology (PPA), and carbon dioxide reduction process development.

AOGA development has focused on improved hydrogen sensors and power supply module redesign. Eliminating

a nitrogen purge to reduce complexity has also been a focus of the AOGA development work. The goal is to deploy

these improvements in the Oxygen Generator Assembly (OGA) aboard the ISS for demonstration.

High pressure oxygen generation work included conducting endurance testing on a 3-cell stack (Giner). This

testing has been progressing satisfactorily. Also, a test rig for evaluating high pressure oxygen generation technologies

was assembled at NASA’s Johnson Space Center (JSC) for delivery to the White Sands Test Facility (WSTF) in

preparation for a series of tests planned in calendar year 2020.

PPA development has focused on demonstrating a carbon trap designed by NASA’s Glenn Research Center (GRC)

and characterizing an electrolytic hydrogen separator. Preparations for evaluating a 3-cell stack electrolytic hydrogen

separator have accomplished test article integration, checkout, and preparing for testing in 2020. Parametric

optimization testing of a 3rd generation PPA also will begin in 2020. Additional developments relating to the PPA

included developing and testing an advanced hydrogen separation membrane and cell stack sealing methods as well

as microgravity plasma modeling.

Advanced technologies for recovering oxygen from carbon dioxide continued to be developed. A trade study and

technology down-selection for candidate carbon formation reactors was completed. A plan is under development to

further develop three candidates that have been designed by pH Matter, NASA’s Marshall Space Flight Center

(MSFC), and Umpqua Research Co. Project plans are in development for testing these reactors toward testing start in

October 2020 with the objective of a final down selection by October 2021. A brassboard Series Bosch (S-Bosch) unit

was assembled and initial testing began.

Ionic liquid applications to oxygen recovery from carbon dioxide were also evaluated during the work period cited

previously. Characterization testing has indicated improvements to incorporate into a second generation equipment

design.

Carbon Dioxide Removal and Management

In parallel with work described elsewhere on developing equipment based on solid amines and physical adsorbents

for demonstration aboard the ISS, work continued on alternative technologies that may be suitable for lunar and Mars

surface exploration applications. The capillary absorption (CapiSorb) technology development continued toward flight

experiment delivery in late calendar year 2021. Liquid amine technology based on diglycol amine (DGA) continued

to evaluate the fluid chemistry and characterize it relative to CO2 sorption and viscosity. Additives such as carbonic

anhydrase are being developed, via directed evolution, for their potential to augment DGA’s working performance. A

breadboard system for characterizing the process’s performance was also developed.

Work on physical adsorption processes included continued work on the air-cooled temperature swing adsorption

compressor (AC-TSAC) for managing and conditioning concentrated CO2 for delivery to downstream reduction

processes. Structured physical sorbents produced by IntraMicron based on 13X zeolites were evaluated in

temperature-vacuum swing (TVS) process cycles. Promising results were obtained showing 72% to 82% CO2 removal

efficiency which exceeds the minimum 68% needed for crewed space exploration mission applications. Development

of metal-organic framework (MOF) materials continued with material acquisition and test plan development for

isotherm characterization. Work is ongoing to acquire isotherm data.

Work continued on development of a cryogenic CO2 deposition process. The sublimation/desublimation process

completed humidity and VOC capture characterization. Future work in 2020 focused on thermal and flow modeling

and the design, fabrication, assembly, and testing of a brassboard system.

Trace Contaminant and Particulate Matter Control

Progress continued to characterize trace contaminant control sorbent media including ion exchange media for gas

phase ammonia removal, impregnated activated carbon for ammonia removal, and multiple volatile organic

compounds (VOC) adsorption on the best performing candidate media to understand co-adsorption effects. Effects of


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flow velocity, high humidity and VOC mixtures on ion exchange media and activated carbon performance were also

investigated.

Work continued toward improving particle filtration technologies for exploration missions. A compact scroll filter

assembly that fits in the volume envelope of an ISS bacteria filter element (BFE) continued through iterative design

improvements. A prototype unit was fabricated and evaluated for pressure drop and filtration efficiency. Performance

testing showed excellent fine dust filtration efficiency.

An exploration architecture trace contaminant control (TCC) test was completed. This integrated test identified

areas for functional architecture optimization. Endurance testing continued on the Microlith-based catalytic oxidizer

technology and early specifications were developed to acquire a brassboard unit that incorporates higher fidelity

components such as sensors, fluid couplings, and power/electrical connectors that are more flight-like. As well, TCC

equipment component sizing, particularly as it relates to the catalytic oxidizer assembly was updated to reflect the

most up-to-date design loads and varied design criteria to incorporate aspects of the toxic hazard index. The impact

on the design by key compounds, primarily formaldehyde versus furan, was also examined.

Process modeling work was conducted on activated carbon adsorption processes using Aspen to improve

multicomponent adsorption predictions compared to heritage FORTRAN models. Computational chemistry work was

also conducted by Suffolk University for a study on volatile methyl siloxane (VMS) decomposition pathways. This

work is indicating gas phase VMS decomposition pathways to dimethylsilanediol (DMSD) are favorable under crewed

spacecraft cabin conditions.

IV. Water Recovery and Management

This section summarizes accomplishments in water recovery, urine recovery, and wastewater stabilization

technical areas.

Water Recovery

Focal areas for water recovery include upgrades to state-of-the-art (SOA) processes and improvements to address

emerging water contaminant challenges.

1. Catalytic Reactor Upgrade

Boeing and Collins Aerospace are scheduled to deliver the upgraded Catalytic Reactor that implements the new

catalyst previously developed by Collins Aerospace, as well as metal seals to replace the rubber seals that have

previously limited life to approximately two years. This new hardware is scheduled to be delivered to ISS in late 2020.

2. Multifiltration Bed Upgrade

The ISS Multifiltration Beds (MFBs) are a major consumable in the Water Processor Assembly (WPA) and NASA

is interested in ways of reducing the logistics resupply requirements for missions. To increase life of the MFBs the

bed materials and packing were redesigned. Boeing and Collins Aerospace are expected to deliver the new MFB in

FY19. This design is a candidate for an exploration system. The new MFB design will implement the Ambersorb 4652

adsorbent as well as replacing the weak base amine exchange resin with the mixed ion exchange resin (Rohm & Haas

IRN-150) already used in the remaining cylinders.

3. Siloxane Removal Study

NASA and Boeing personnel have developed two mitigation strategies to reduce VMS compound loading in the

cabin atmosphere toward mitigating highly water soluble decomposition product production to which the water

processing system is sensitive. These strategies include VMS compound source reduction and supplemental cabin

atmospheric scrubbing. To reduce VMS compound sources, new siloxane-free wipes and hygiene products have been

identified and delivered to the ISS for crew use. To supplement basic cabin trace contaminant control capabilities, a

new siloxane filter design was installed in July 2019 upstream of each U.S. Segment condensing heat exchanger. The

combination of source reduction and siloxane filters has reduced the atmospheric siloxane concentration and the

resulting concentration of DMSD in the condensate collected in the U.S. Segment.

Urine Recovery

Developmental efforts in urine recovery have addressed upgrades to the SOA urine processing system,

development of alternative urine processing techniques, and recovering water from the concentrated byproduct

produced by urine recovery processes.

1. Urine Processor Assembly

Upgrades to the Urine Processor Assembly (UPA) have continued to progress. The design to incorporate Pressure

Control and Pump Assembly and the Separator Plumbing Assembly, named the Purge Pump Separator Assembly, has


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completed design reviews and is planned for delivery in the first quarter of calendar year 2021. The Distillation

Assembly with the latest design upgrades has been delivered to the ISS and is awaiting installation into the UPA.

2. Brine Dewatering

Brine Dewatering seeks to address the goal of 98% water recovery established by the Human Health, Life Support,

and Habitation Systems roadmap. Ninety-eight percent water recovery cannot be achieved without recovery of water

from brine.

Paragon Space Development Corp. has completed functional testing of their Brine Processor Assembly (BPA),

demonstrating the technology met functional requirements. During vibration and electromechanical effects testing

issues were uncovered with the power system that required redesign. Upon completion of the redesign the tests will

be repeated and the BPA will be delivered for flight. The unit is planned to be delivered in August 2020 for flight

demonstration on the ISS. Available space on flights prior to the BPA flight has provided the opportunity to fly the

brine bags and integration hardware early.

3. Biological Water Processor

A biological water processor (BWP) is intended to aid in closed-loop life support systems development aimed at

high water recovery rates by performing water remediation by encouraging urea hydrolysis and the speciation of

ammonium. The BWP utilizes the natural metabolic processes of bacteria, rather than limiting their growth, to nitrify

and oxidize ammonium in aerobic environments.

Collaboration with Texas Tech University on this technology continues. Texas Tech completed a three year

hibernation and hydrocarbon loading study with one their Membrane Aerated Biological Reactor (MABR). They have

passed four years of treating ISS equivalent water treatment with another MABR. Texas Tech is also working with

Pancopia for inoculum and dual stage reactor development. Initial discussions for a for a flight technology

demonstration have started.

A second collaboration for bioregenerative water purification with the University of South Florida (USF)

continued. USF is developing an Anaerobic Membrane Reactor (AnMBR) for the treatment of fecal and food waste.

USF is set to deliver the reactor to NASA’s Kennedy Space Center (KSC) for testing in April 2020. KSC will also

integrate a Photo-Membrane Bioreactor (PMBR) that treats urine, hygiene, and Anaerobic Membrane Reactor

(AnMBR) permeate to test an integrated bioregenerative water purification system.

Wastewater Stabilization

Wastewater stabilization is an essential component of the spacecraft water cycle. There is typically a time gap

between wastewater generation events (showers, urination, etc.) and processing the wastewater as well as between

processing wastewater and consuming potable water. In these time intervals, the water must be stored and microbial

growth must be mitigated. Developmental work during the past year has focused on silver biocide technology for

mitigating microbial and biofilm growth.

The goals of silver biocide technology development tasks are to identify methods for adding biocidal silver to

water on-orbit during both operational use and dormancy, as well as methods to maintain the concentration in stored

water over long periods of time. Work continued on the silver dosing, materials compatibility, and sensing.

Two methods for silver dosing continue development. The active dosing system uses silver electrodes to introduce

silver into the water. This year testing on a commercial marine doser to inform the design of a breadboard system

were completed. Based on the results a breadboard doser was completed in February 2020 and optimization testing

started that will characterize performance for a brassboard development. The passive dosing method uses silver

impregnated foam to dose the water. Testing of the foam demonstrated the goal of 20 g of silver full scale system with

an initial release rate of greater than 20 ppb at one minute and maintaining a greater than 200 ppb concentration longer

than six months at a 0.1 L/min flow rate is achievable.

Materials compatibility testing with the initial test articles did not result in a selection. Additional materials

research and testing continues. Coatings to apply to materials continue to be investigated as a way to mitigate sliver

plating.

Sensing of silver has proven to be a challenge as the conductivity of the water for a spacecraft is low. Therefore,

current commercial methods are not proving effective. Indirect methods can be used to determine silver content if a

sensing system cannot be developed.


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V. Waste Management

This section summarizes accomplishments in metabolic waste management and trash management technical areas.

Metabolic Waste

The project to develop, deliver, install and evaluate toilets for use on board ISS, Orion and future crewed spacecraft

and habitats made significant progress in 2019. The dual fan separator (DFS) is a key component of the Universal

Waste Management System (UWMS). Each UWMS, or toilet, collects urine using the DFS for air suction which also

removes air from the stream. Fecal material is collected in hard sided machined canisters that use the air flow to aid

in collection and for odor control. The toilet seat and funnel were designed by NASA to improve ease of use by female

crew members.

Delivery of the first Orion UWMS flight unit in December 2019 capped a busy year for the project. The Orion

UWMS unit, collects urine, uses oxone tablets for urine pretreatment and then stores the urine in a separate tank

outside the UWMS until it is vented from the vehicle. The Orion UWMS completed successful testing including

functional testing at Collins Aerospace Houston and six environmental tests at NASA JSC. Final functional testing at

Collins showed no issues and the unit arrived at NASA KSC in December 2019.

The ISS UWMS unit is more complex because of the addition of a dosing assembly for delivery of strong acid

urine pretreat into the urine stream before it is delivered to the ISS Urine Processor Assembly and is still in assembly

and testing.6 There are slight differences between the two units aside from the additional dosing assembly. The

controller cover, commode lid, and acoustic enclosure were all modified in shape to allow for the physical constraints

of the Artemis-2 Hygiene Bay. The urine block which contains the mounting location and fluid path for the solenoid

valve and pressure sensor is slightly different due to the additional outlet vent hose for Orion.

Delivery of the ISS UWMS is expected in March 2020 for launch in August 2020. Consumables to support on-

orbit testing will also be delivered. A technical demonstration period with usage aboard the ISS by a minimum of

three crewmembers will complete the contract. Assuming a launch in August 2020, the demonstration will likely

complete within the 2020 calendar year.

Trash Management

NASA continued development of Heat Melt Compactor (HMC) technology for processing of non-hazardous trash

and is seeking to use a reliable technology to reduce trash volume and stabilize trash for long-term storage.

Compression and melting of the raw trash provide a 7:1 reduction in trash volume. HMC also provides water recovery,

and the resultant “tiles” are microbiologically-stable, low-volume products. This increases habitable volume and

improves long term vehicle hygiene. The HMC can potentially be used to augment radiation protection. For a one-

year mission of four-crew, it is estimated that an HMC could recover ~8 cubic meters of habitable volume and recover

230 kg of water from ~1,300 kg of trash.

A full-scale, second-generation (Gen2) HMC, has been developed and is being used to finalize process parameters

in ground tests. These results will be used to inform development of a unit for an ISS technology demonstration. These

NASA risk reduction activities continue in three areas: 1) modifying HMC Gen 2 to be used as a facility to test and

validate contractor HMC design concepts; 2) developing a dew point measuring system for processed off-gas/water

vapor mixtures as related to ISS venting requirements; and 3) validating an Adsorption Water Recovery System to

collect water during processing in microgravity.

The flight development of HMC technologies began in FY19 with the award of two contracts for HMC-like Trash

Compaction and Processing Systems (TCPS) under NASA’s NextSTEP partnership with industry. The contracts were

awarded to Sierra Nevada Corporation and Collins Aerospace. Each company has completed a concept and

preliminary requirements review. In September FY20 Collins will present an abbreviated Preliminary Design Review

(PDR) and in October FY21 SNC will present their abbreviated PDR. Completion of the PDR’s will complete Phase

A. Phase B is expected to follow, in which an ISS flight demonstration unit will be designed, built and tested

Other activities supporting this element include related HMC technologies, such as flow meters that can measure

HMC effluent water rates, and gas effluent characterization and treatment. Also, in FY19 a Phase IIE SBIR contract

was awarded to Materials Modification, Inc. for further development and testing of their semi-permeable trash

containment bags. In addition to these bags being tested in the HMC, they will also be tested with the fecal Torrefaction

Processing System being developed under a Phase IIX SBIR contract by Advanced Fuel Research in FY20.


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VI. Environmental Monitoring

This section summarizes accomplishments in microbial monitoring, combustion product monitoring, and water

quality monitoring technical areas.

Microbial Monitoring

In 2017, NASA published the results of the first-of-its-kind DNA sequencing in space.7 Using the MinION DNA

sequencer (Oxford Nanopore Technologies, Oxford, UK), ISS crew demonstrated DNA sequencing of known, frozen

samples. The in-flight results were compared to terrestrial samples and traditional, NASA laboratory sequencing

methods (Illumina MiSeq and PacBio RS II sequencing platforms). Upon analysis of the comparative results, the team

concluded that the performance of the MinION platform was neither adversely affected by transport to the ISS, nor

by loading or operation in its microgravity environment. Later that same year, an end-to-end sample preparation

method including DNA extraction, DNA amplification, and library preparation was tested aboard the ISS using DNA

from a microbial mock community.8 Successful demonstration of sample preparation in space resulted in the use of

this process for environmental microbial monitoring. Microorganisms that were collected from and cultured aboard

the ISS as part of routine culture-based monitoring were identified on-orbit through 16S rDNA MinION sequencing,

resulting in the first identification of microbes collected and cultured entirely off Earth.10 Building on the ability to

identify cultured microorganisms, a culture-independent, swab-to-sequencer method for microbial identification was

developed and tested aboard the ISS. Four independent swab-to-sequencer experiments were conducted and

microorganisms identified from these ISS surfaces are both representative of historical culture data and are commonly

associated with the human microbiome.9 While the data reduction is on-going and the peer-reviewed journal

publication is pending, the effort returned multiple swabs to the ground for comparative analysis to the data generated

by MinION on-board ISS. To date, the MinION has been used successfully in 30 ISS sequencing experiments.

Building on these successes, the latest terrestrial MinION work has focused on potable water sequencing using

MinION. Work in 2019 demonstrated that direct-to-sequencer analysis of potable water containing less than 100

colony forming units per mL (CFU/mL) of bacteria is unsuccessful and that those samples would require a pre-

concentrating step. The MinION team is developing a method utilizing a small dime-sized filter in conjunction with

the swab-to-sequencer method to demonstrate potable water sampling that is capable of detecting bacteria in water

that meets or exceeds ISS requirements for potable water health (< 50 CFU/mL). The team is also continuing work in

quantification, aiming to inform new potable water health requirements based on DNA sequencing rather than culture-

based methods. In addition, the MinION team is validating novel new hardware from Oxford Nanopore, aimed at

further ease-of-use, with an emphasis on MinION’s potential to multiplex multiple samples (or surface sampling

locations) into a simple MinION sequencing run, reducing the consumables required in order to determine crew and

vehicle health.

A separate concentrator effort is on-going, born from an SBIR contract with Innovaprep LLC (Drexel, MO). The

Innovaprep ISS Smart Sample Concentrator (iSSC) is an adaptation of a commercially available concentrating pipette

using a hollow fiber membrane filter.10 Dispensed from a cartridge, carbonated foam dislodges the concentrated

bacteria from the membrane surface and dispenses them into a 0.5 mL sample cartridge. In 2020, NASA will test

approximately 100 concentrators to determine the accuracy of the concentrator. In 2020, NASA hopes to down select

a concentration method from these contenders.

Combustion Product Monitoring

Development of the next-generation combustion-products monitor, the Anomaly Gas Analyzer (AGA), by the ISS

Program in tandem with the Orion Program, continued, working to a delivery date of the initial, certified flight units

by December-2021. The AGA integrates two forms of spectroscopy into a single unit to measure gases. An integrating

sphere is employed as a multi-pass, optical cell to measure the concentration of CO2 (carbon dioxide), O2 (oxygen),

HCl (hydrochloric acid), HF (hydrofluoric acid), and NH3 (ammonia) in the cabin atmosphere by absorption

spectroscopy. In addition, a photo-acoustic cell is employed to measure the concentrations of HCN (hydrogen

cyanide), CO (carbon monoxide), and N2H4 (hydrazine) by photoacoustic spectroscopy. In addition to these target

gases, the AGA will also provide readings for temperature, concentration of water vapor, and total pressure.

The AGA will serve as the combustion products monitor, ammonia/hydrazine monitor, and portable carbon

dioxide monitor and oxygen monitor for ISS and the Orion vehicle. For ISS the AGA replaces the CSA-CP

(Compound Specific Analyzer-Combustion Products), the Draeger-based Ammonia Monitor Kit (comprised of

ammonia Draeger tubes and the Draeger Chip Measurement System (CMS), and the Carbon Dioxide Monitors

(CDMs)). It should be noted that despite the fact that AGA has the capability to measure oxygen, the current Portable


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Oxygen Monitors (POMs) will remain operational on-board ISS primarily for EVA pre-breathe activity. POM and

AGA can be used for spot-checks in areas where oxygen concentration may have decreased due to poor circulation.

However, the POM will remain as the backup for the Major Constituent Analyzer (MCA) with respect to oxygen

monitoring. For the Orion vehicle, ammonia and hydrazine are required for off-nominal post-landing operations in

which post-landing ventilation is needed and/or re-entry occurs with a depressurized vehicle. In either off-nominal

situation, a risk exists of either leaked hydrazine or ammonia entering the cabin prior to hatch opening. The AGA will

provide crew a means to measure the cabin atmosphere to determine whether further crew-action is required. Three

engineering development units (EDUs) were delivered to the Toxicology and Environmental Chemistry (TEC)

Laboratory at NASA JSC in August 2018, for testing.

The AGA will have two operational modes: (1) On-orbit Mode, and (2) Post-landing Mode. In Post-landing mode,

the AGA will display the concentrations of CO2, NH3, N2H4, and water vapor, temperature, and pressure. In On-orbit

Mode, the AGA will display the concentrations of CO, HCl, HF, HCN, CO2, O2, NH3, water vapor, temperature, and

pressure.

A critical design review (CDR) for the AGA was completed in May 2019. A CDR findings was successfully

completed in June 2019, with six actions to track as forward work, and the AGA team was officially given authority

to proceed with production and certification of flight units.

Unfortunately, in November 2019, an EDU was subjected to shock testing per CDR forward work resulting in

damage to the unit. What initially appeared to be a failure of the photoacoustic cell for measuring hydrazine was

actually much worse. Upon further inspection, it was determined that the commercial-of-the-shelf (COTS) hydrazine

laser experienced catastrophic failure. While solutions to the various failures were determined, the only solution to a

failed COTS hydrazine laser was to have the maker of the laser redesign the unit to increase robustness to pass the

shock test. This solution proved to be cost and schedule prohibitive. By mid-January 2020, in a joint ISS and Orion

Program Government Equipment and Material Control Board meeting, the decision was made to remove the hydrazine

capability from the AGA and have crew rely on an alternative means to determine the presence of hydrazine in the

Orion cabin during post-landing operations. Even though hydrazine will not be reported, the Post-Landing Mode of

AGA will remain intact, providing readings for CO2, ammonia, temperature, pressure and water vapor. Currently, the

TEC Laboratory at NASA JSC was tasked to assess, recommend, and provide a means for hydrazine detection for the

Orion vehicle meeting the constraints imposed by the vehicle and by the concept of operations. AGA internal redesign

based on shock testing has been completed.

Water Quality Monitoring

For current and future regenerable water systems, monitoring of total organic carbon (TOC) in potable water is a

baseline requirement for maintaining crew health by meeting water potability requirements. During the operation of

ISS, NASA has relied upon the ISS Total Organic Carbon Analyzer (TOCA) to quantify TOC in ISS product water

for both toxicity awareness and system health and performance. For future exploration missions, a TOC analyzer will

need to perform reliably, efficiently, with limited or no consumables requiring resupply and at a lower mass/volume

envelope when compared to the ISS TOCA.11 This development is called the “miniTOCA”.

In FY18, an extensive commercial technology review failed to yield a single, commercially available analyzer that

would meet all the requirements, especially those requirements levying gravity independence, restricting hazardous

acids and chemicals or limiting high temperatures. Accordingly, the team has pursued a component-level development

approach, focused on oxidation and detection methods separately. Summarized elsewhere,12 six oxidation or detection

methods were selected for the evaluation. In FY19, the MiniTOCA team procured the six commercially available

components and configured them into four breadboards for testing. In early FY20, the four breadboard configurations

were evaluated and resulted in the selection of the breadboard on which to architect the flight design. The selected

TOC analysis system utilizes ultraviolet (UV) oxidation with membrane transfer via nitrogen (N2) sweep gas to a

tunable laser spectrometer (TLS) for CO2 detection. The system was selected due to its reliable analytical performance

through nitrogen sweep gas and known engineering flow controls. The miniTOCA team is building a ground

development unit in FY20 and begin the flight demonstration design, build and certification process in FY21,with a

goal of delivering the flight article in FY23 for testing on board ISS.


11

VII. Analysis Supporting ECLSS Testing Strategies

Supportability will be a much greater challenge for future deep-space missions than it has been in the past. Crewed

missions to Mars will require systems to operate in logistical isolation for an order of magnitude longer than previous

missions – up to 1,200 days without resupply for a Mars mission, compared to a record of 119 days between resupply

in LEO. As a result, these systems will face greater risk of subsystem or component failure during the mission, and

will have to carry more spares to mitigate that risk.13-16 The logistics and in-flight maintainability strategies will be

key to mission success.

Gaining improved insight on ECLSS equipment failure mechanisms and reliability aids in reducing uncertainty

inherent to reliability predictions and establishing system supportability strategies. This insight also helps define

reliability testing methods that supplement NASA-STD-5017, NASA Standarard 5017, Design and Requirements for

Mechanisms, that is necessary to identify failure modes and modify designs toward increasing the mean time between

failures. Toward developing the reliability testing methods, NASA is performing an in-depth review of twenty years

of experience of ECLSS operations aboard the ISS to characterize the state-of-the-art in ECLSS reliability and

supportability. These data are being used to identify high-value targets for reliability growth and uncertainty reduction

as well as to project potential reliability and supportability improvements as a function of testing. This activity will

guide applying best practices for using highly accelerated life testing, accelerated life testing, and standard life testing

methods in a cost- and schedule-effective manner.

Life testing, reliability testing, and testing for robustness is accomplished with ground testing where multiple units

can be under test and can be tested beyond their design limits without endangering crew or spacecraft. Testing on the

ISS/LEO platform allows for operation in the microgravity environment that will uncover issues with operating in

microgravity that cannot be tested for on the earth.

VIII. Conclusion

The past year’s investments in ECLSS have made steady progress at closing technology gaps for both near term

and future exploration missions. One overall conclusion is that ISS testing and endurance ground testing are essential

to validating developed technologies for exploration. Over the next year analysis will be refined to help inform which

systems’ reliability and which new technologies will be targeted to bring down the departure mass for exploration,

particularly for Mars transit missions. It is not practical to cover all the ECLSS capability activities within the page

limitations. Readers are encouraged to review the references for details on the activities outlined in this paper. As

NASA continues to team with commercial and international partners, academia, and other government agencies, the

successes are multiplying and the pace is quickening toward an outpost in cis-lunar space and Artemis missions to the

moon as the first steps to pioneering space.

Acknowledgments

Funding for these activities comes from a wide range of programs including: Advanced Exploration Systems, ISS,

Orion, SBIR office, Space Technology Mission Directorate, and investments by industry partners. The authors would

like to acknowledge the many team members across NASA, industry and academia working to make these projects

successful and enable future exploration missions. The authors thank Carrole Hedges of NASA MSFC for her

diligence in consolidating author contributions to this paper.


12

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NASA Environmental Control and Life Support Technology