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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
NASA NTRS2005

Irregular Satellites of the Planets

This proposal is directed towards the observational exploration of the irregular satellite systems of the planets. Primarily we use large-format CCD cameras on the world's largest telescopes, on Mauna Kea, to discover new irregular satellites and then to monitor their positions in order to ascertain their orbital characteristics. Separate observations are taken to determine the physical properties of the irregular satellites. The big picture science objective is to determine how these satellites were captures, and to use the properties of the satellites and their orbits to place constraints on early solar system (including formation) processes. Work in the first year has focussed on a major investigation of the Saturn irregular satellite system. We secured observing time on the Subaru and Gemini 8-m diameter telescopes in December 2004, January, February and March 2005 for the conduct of a deep, wide-area survey. This has resulted in the detection and orbit determination for 12 new satellites to be announced in the next week or two. Additional satellites were lost, temporarily, due to unusually poor weather conditions on Mauna Kea. These objects will be recovered and their orbits published next year. A separate survey of the Uranus irregular satellites was published (Sheppard, Jewitt and Kleyna 2005). Away from the telescope, we have discovered the amazing result that the four giant planets possess similar numbers of irregular satellites. This flies in the face of the standard gas-drag model for satellite capture, since only two of the giant planets are gas giants and the others (Uranus and Neptune) formed by a different process and in the absence of much gas. The constancy of the satellite number (each giant holds approximately 100 irregular satellites measured down to the kilometer scale) is either a coincidence, with different capture mechanisms at different planets giving by chance the same total numbers of irregular satellites, or indicates that the satellites were captured by a completely different process. We favor the latter (Jewitt and Sheppard 2005).

Jewitt, David↗
NASA NTRS2016

Rodent Habitat on ISS: Advances in Capability for Determining Spaceflight Effects on Mammalian Physiology

Rodent research is a valuable essential tool for advancing biomedical discoveries in life sciences on Earth and in space. The National Research Counsel's Decadal survey (1) emphasized the importance of expanding NASAs life sciences research to perform long duration, rodent experiments on the International Space Station (ISS). To accomplish this objective, new flight hardware, operations, and science capabilities were developed at NASA ARC to support commercial and government-sponsored research. The flight phases of two separate spaceflight missions (Rodent Research-1 and Rodent Research-2) have been completed and new capabilities are in development. The first flight experiments carrying 20 mice were launched on Sept 21, 2014 in an unmanned Dragon Capsule, SpaceX4; Rodent Research-1 was dedicated to achieving both NASA validation and CASIS science objectives, while Rodent Reesearch-2 extended the period on orbit to 60 days. Groundbased control groups (housed in flight hardware or standard cages) were maintained in environmental chambers at Kennedy Space Center. Crewmembers previously trained in animal handling transferred mice from the Transporter into Habitats under simultaneous veterinary supervision by video streaming and were deemed healthy. Health and behavior of all mice on the ISS was monitored by video feed on a daily basis, and post-flight quantitative analyses of behavior were performed. The 10 mice from RR-1 Validation (16wk old, female C57Bl6/J) ambulated freely and actively throughout the Habitat, relying heavily on their forelimbs for locomotion. The first on-orbit dissections of mice were performed successfully, and high quality RNA (RIN values>9) and liver enzyme activities were obtained, validating the quality of sample recovery. Post-flight sample analysis revealed that body weights of FLT animals did not differ from ground controls (GC) housed in the same hardware, or vivarium controls (VIV) housed in standard cages. Organ weights analyzed post-flight showed that there were no differences between FLT and GC groups in adrenal gland and spleen weights, whereas FLT thymus and liver weights exceeded those of GC. Minimal differences between the control groups (GC and VIV) were observed. In addition, Over 3,000 aliquots collected post-flight from the four groups of mice were deposited into the Ames Life Science Data Archives for the Biospecimen Sharing Program and Genelab project. New capabilities recently developed include DEXA scanning, grip strength tests and male mice. In conclusion, new capability for long duration rodent habitation of group-housed rodents was developed and includes in-flight sample collection, thus avoiding the complication of reentry. Results obtained to date reveal the possibility of striking differences between the effects of short duration vs. long duration spaceflight. This Rodent Research system enables achievement of both basic science and translational research objectives to advance human exploration of space.

Bone Loss↗
NASA NTRSDate not supplied

Deep Space Navigation for the BioSentinel CubeSat Science Orbit

BioSentinel is a 6U CubeSat active in heliocentric orbit, as of April 2024. The spacecraft was launched aboard the first SLS flight as part of the Artemis-I campaign in November 2022. After successful separation from the upper stage of SLS, it performed a lunar flyby which provided the necessary energy to achieve an Earth-trailing heliocentric orbit. This paper includes a description of the final science orbit as well as its evolution, the techniques and procedures utilized to perform the orbit determination and a description of the overall navigation campaign, with emphasis on the heliocentric orbit operations.

Jose Alvarellos↗
NASA NTRS2018

Working Fluid Trade Study for a Two-Phase Mechanically Pumped Loop Thermal Control System

NASA Jet Propulsion Laboratory is investigating a two-phase mechanically pumped fluid loop (MPFL) technology for spacecraft thermal control for future planetary space science mission concepts. The two-phase technology combines the potential of single-phase MPFL and the passive two-phase heat pipe systems. Previous two-phase MPFL studies at JPL have identified an evaporator system with a separated flow architecture as providing a robust light mass thermal control system with very high spatial and temporal thermal stability required by the science instruments on these missions. These studies have further identified the thermophysical properties of the working fluid to be key to the performance of a two-phase fluid loop. This paper describes the methodology used in the selection of the working fluids for optimizing the performance of the two-phase MPFL. A high level model was developed that includes the constraints and boundaries driven by the system components. The performance of fluids from the REFPROP database are investigated and rated for this system. The working fluid attributes such as cost, hazardous properties, and heritage were taken into account in this selection. A typical spacecraft dissipating 1000 W and a fluid loop consisting of an evaporator, accumulator, radiator, and associated tubing components is used as an example in this study.

Daimaru, Takuro↗
NASA NTRS2018

Working Fluid Trade Study for a Two-Phase Mechanically Pumped Loop Thermal Control System

NASA Jet Propulsion Laboratory is investigating a two-phase mechanically pumped fluid loop (MPFL) technology for spacecraft thermal control for future planetary space science mission concepts. The two-phase technology combines the potential of single-phase MPFL and the passive two-phase heat pipe systems. Previous two-phase MPFL studies4,5 at JPL have identified an evaporator system with a separated flow architecture as providing a robust light mass thermal control system with very high spatial and temporal thermal stability required by the science instruments on these missions. These studies have further identified the thermophysical properties of the working fluid to be key to the performance of a two-phase fluid loop. This paper describes the methodology used in the selection of the working fluids for optimizing the performance of the two-phase MPFL. A high level model was developed that includes the constraints and boundaries driven by the system components. The performance of fluids from the REFPROP database were investigated and rated for this system. The working fluid attributes such as cost, hazardous properties, and heritage were taken into account in this selection. A typical spacecraft dissipating 1000 W and a fluid loop consisting of an evaporator, accumulator, radiator, and associated tubing components was used as an example in this study.

Daimaru, Takuro↗
NASA NTRS1977

Viking 75 project: Viking lander system primary mission performance report

Viking Lander hardware performance during launch, interplanetary cruise, Mars orbit insertion, preseparation, separation through landing, and the primary landed mission, with primary emphasis on Lander engineering and science hardware operations, the as-flown mission are described with respect to Lander system performance and anomalies during the various mission phases. The extended mission and predicted Lander performance is discussed along with a summary of Viking goals, mission plans, and description of the Lander, and its subsystem definitions.

Cooley, C. G.↗
NASA NTRS2004

Microtechnology in Space: NASA's Lab-on-a-Chip Applications Development Program

NASA's Marshall Space Flight Center (MSFC) Lab on a Chip Application Development LOCAD) team has worked with microfluidic technology for the past few years in an effort to support NASA's Mission. In that time, such microfluidic based Lab-on-a-Chip (LOC) systems have become common technology in clinical and diagnostic laboratories. The approach is most attractive due to its highly miniaturized platform and ability to perform reagent handling (i-e., dilution, mixing, separation) and diagnostics for multiple reactions in an integrated fashion. LOCAD, along with Caliper Life Sciences has successfully developed the first LOC device for macromolecular crystallization using a workstation acquired specifically for designing custom chips, the Caliper 42. LOCAD uses this, along with a novel MSFC-designed and built workstation for microfluidic development. The team has a cadre of LOC devices that can be used to perform initial feasibility testing to determine the efficacy of the LOC approach for a specific application. Once applicability has been established, the LOCAD team, along with the Army's Aviation and Missile Command microfabrication facility, can then begin to custom design and fabricate a device per the user's specifications. This presentation will highlight the LOCAD team's proven and unique expertise that has been utilized to provide end to end capabilities associated with applying microfluidics for applications that include robotic life detection instrumentation, crew health monitoring and microbial and environmental monitoring for human Exploration.

Monaco, Lisa↗
NASA NTRSDate not supplied

Optimization of the Lunar Icecube Trajectory Using Stochastic Global Search and Multi-Point Shooting

Lunar IceCube is a 6U cubesat that will launch on NASA’s Artemis 1 mission in 2021. Lunar IceCube will separate from Artemis 1 shortly after trans-lunar injection (TLI) and travel to its science orbit about the moon using its Busek Ion Thruster 3 (BIT-3) propulsion system. This paper describes a technique to rapidly design Lunar IceCube trajectories using the monotonic basin hopping (MBH) stochastic global search algorithm, along with low- and high-fidelity multi-point shooting transcriptions. This technique allows the Lunar IceCube team to rapidly adapt to changing initial conditions, spacecraft properties, and operational constraints.

optimization↗
NASA NTRS2011

A Pragmatic Path to Investigating Europa's Habitability

Assessment of Europa's habitability, as an overarching science goal, will progress via a comprehensive investigation of Europa's subsurface ocean, chemical composition, and internal dynamical processes, The National Research Council's Planetary Decadal Survey placed an extremely high priority on Europa science but noted that the budget profile for the Jupiter Europa Orbiter (1EO) mission concept is incompatible with NASA's projected planetary science budget Thus, NASA enlisted a small Europa Science Definition Team (ESDT) to consider more pragmatic Europa mission options, In its preliminary findings (May, 2011), the ESDT embraces a science scope and instrument complement comparable to the science "floor" for JEO, but with a radically different mission implementation. The ESDT is studying a two-element mission architecture, in which two relatively low-cost spacecraft would fulfill the Europa science objectives, An envisioned Europa orbital element would carry only a very small geophysics payload, addressing those investigations that are best carried out from Europa orbit An envisioned separate multiple Europa flyby element (in orbit about Jupiter) would emphasize remote sensing, This mission architecture would provide for a subset of radiation-shielded instruments (all relatively low mass, power, and data rate) to be delivered into Europa orbit by a modest spacecraft, saving on propellant and other spacecraft resources, More resource-intensive remote sensing instruments would achieve their science objectives through a conservative multiple-flyby approach, that is better situated to handle larger masses and higher data volumes, and which aims to limit radiation exposure, Separation of the payload into two spacecraft elements, phased in time, would permit costs to be spread more uniformly over mUltiple years, avoiding an excessively high peak in the funding profile, Implementation of each spacecraft would be greatly simplified compared to previous Europa mission concepts, minimizing new development while achieving the key Europa science objectives. We will report on the status of this evolving concept, and will solicit community feedback, as we pursue an innovative and low-cost ways to explore Europa and investigate its habitability.

Pappalardo↗
NASA NTRSDate not supplied

AERACEPT (AErosol Rapid Analysis Combined Entry Probe/sonde Technology) for the Nephele Venus Cloud Mission Concept

Nephele is a small atmospheric probe mission concept to determine whether the Venus clouds contain organic matter. Nephele complements larger missions that seek to conduct Venus atmospheric analyses, such as DAVINCI, Venera-D, and the Morning Star missions, by directly sampling and analyzing cloud and haze particles. AERACEPT is an aerosol sampling technology designed to minimize the mass, volume, and complexity required for in situ planetary atmosphere characterization. A single aeroshell functions as a combined entry vehicle, descent probe, and instrumented sonde, combining recent advances in thermal protection materials with heritage technology from planetary and airborne science. The velocity of descent drives aerosol through inlets embedded in the aeroshell’s thermal protection material; inertial separation isolates the particles from the gas stream; and the particle capture surface doubles as the analysis substrate. This method can work without heat shield separation, descent control, or active sample handling; these advantages trade against a smaller sample volume, higher risk of sample heating, and shorter time for analysis and data return. AERACEPT further benefits from modeling of the internal and external flow to understand the particle capture efficiency and bias for size and concentration distributions. AERACEPT is well suited for a Venus mission such as Nephele, where a passive descent trajectory is both subsonic over the altitudes of interest and provides sufficient velocity and pressure differential for the particle sizes of interest. A thermal and flow toolchain developed in-house (Traj→ DPLR→ PATO→ openFOAM) was used to model an 80-cm aeroshell with science operations 63–39 km. These models indicate that AERACEPT will provide ~24 µL accumulated sample of particles ≥ 0.2 µm, substantially above the 2 µL threshold requirement. The worst-case particle heating will be ~14 K above ambient, for the smallest particles at the lowest altitude; most particles will experience ≤ 1 K rise, at which almost all analytes of interest will be unaffected. Plasma jet testing of a small-scale aeroshell-material inlet was recently conducted to validate the thermal model parameters; wind tunnel testing to validate the flow model parameters is underway.

AERACEPT↗
NASA NTRS2001

Flight Computer Design for the Space Technology 5 (ST-5) Mission

As part of NASA's New Millennium Program, the Space Technology 5 mission will validate a variety of technologies for nano-satellite and constellation mission applications. Included are: a miniaturized and low power X-band transponder, a constellation communication and navigation transceiver, a cold gas micro-thruster, two different variable emittance (thermal) controllers, flex cables for solar array power collection, autonomous groundbased constellation management tools, and a new CMOS ultra low-power, radiation-tolerant, +0.5 volt logic technology. The ST-5 focus is on small and low-power. A single-processor, multi-function flight computer will implement direct digital and analog interfaces to all of the other spacecraft subsystems and components. There will not be a distributed data system that uses a standardized serial bus such as MIL-STD-1553 or MIL-STD-1773. The flight software running on the single processor will be responsible for all real-time processing associated with: guidance, navigation and control, command and data handling (C&DH) including uplink/downlink, power switching and battery charge management, science data analysis and storage, intra-constellation communications, and housekeeping data collection and logging. As a nanosatellite trail-blazer for future constellations of up to 100 separate space vehicles, ST-5 will demonstrate a compact (single board), low power (5.5 watts) solution to the data acquisition, control, communications, processing and storage requirements that have traditionally required an entire network of separate circuit boards and/or avionics boxes. In addition to the New Millennium technologies, other major spacecraft subsystems include the power system electronics, a lithium-ion battery, triple-junction solar cell arrays, a science-grade magnetometer, a miniature spinning sun sensor, and a propulsion system.

Speer, David↗
NASA NTRS2022

New Rover Conops with High-Performance Onboard Computing: Give Up Raw Data to Reduce Ops Cost and Do More Science

A major portion of time during the tactical operation of Mars rovers is spent for selecting, prioritizing, and coordinating sciences and engineering activities such that they fit within resource constraints, including the downlink data volume, energy, and time. In particular, the downlink data volume constraint is getting particularly tighter in recent missions because modern instruments produce increasingly high data volume while the communication bandwidth is essentially bounded by the law of physics. Tactical operation would be substantially simplified, hence the operation cost could be reduced, if the data volume constraint is relaxed or even removed. In this abstract, we propose a new operation paradigm for achieving this goal. The key observation is that, both in science and engineering applications, the bit size of raw data is typically much greater than the volume of processed information that is needed for scientific or engineering analysis. For example, a full-resolution image from Mastcam-Z, the main science camera on Perseverance, is about 700 kB in volume and we downlinked 29,685 images up to Sol 243, totaling ~20 GB of data. But of course, scientists do not use every pixel of these images; what they really look for in the images are geological features, typically represented by specific geometric configurations or textures. An end product after processing hundreds of Mascam-Z images could be a single geological map summarizing the spatial distribution of the features. For another example, a 100-meter drive of Perseverance produces 7-12 MB of drive telemetry, which records every detail of the rover's motion at 8 Hz, including position, attitude, steering angles, encoder readings, motor currents and many other information. But what the ground engineers eventually pay attention to is the signs of anomaly, such as excessive motor currents or high slip; if a drive is nominal, the vast majority of this data is unused. What if, then, we process the raw data onboard and only downlink the processed data that is relevant to scientific or engineering analyses, such as a list of detected science features (with cropped images) or a list of potential signs of anomaly while driving? A major roadblock for such onboard, high-level information processing has been the onboard computational resource. RAD750, the main onboard computer of Perseverance, is obviously not sufficient for performing complex image or signal processing such as object detection, semantic segmentation, or anomaly detection. Interestingly, RAD750 is not the best processor that Perseverance has; Qualcomm's Snapdragon 801, a modern mobile processor, is on her Heli Base Station, a device for communicating with Mars Helicopter Ingenuity; also, Intel's Atom E3845 processors are on engineering cameras. In the reminder of this paper, we will introduce two particular uses cases of these high-performance co-processors (meaning auxiliary CPU, GPU, or other types of processors that are separate from the main processor that runs the main flight software) for lowering operation cost and accommodating more science activities for a given communication constraint.

Didier, A.↗
NASA NTRS1994

Influence of flow on interface shape stability in low gravity

The objectives are to: (1) Understand the influence in low gravity of flow on interface shape. For example, document and control the influence of axial flow on the Plateau-Rayleigh instability of a liquid bridge; and (2) Extend the ground-based density-matching technique of low gravity simulation to situations with flow; that is, develop Plateau chamber experiments for which flow can be controlled. Containerless containment of liquid by surface tension has broad importance in low gravity. For space vehicles, the behavior of liquid/gas interfaces is crucial to successful liquid management systems. In microgravity science, free interfaces are exploited in various applications. Examples include float-zone crystal growth, phase separation near the critical point of liquid mixtures (spinoidal decomposition) and quenching of miscibility gap molten metal alloys. In some cases, it is desired to stabilize the capillary instability while in others it is desired to induce capillary breakup. In all cases, understanding the stability of interface shape in the presence of liquid motion is central.

Steen, Paul H.↗
NASA NTRS1996

The Advanced Automated Directional Solidification Furnace

The Advanced Automated Directional Solidification Furnace (AADSF) is a five zone tubular furnace designed for Bridgman-Stockbarger, other techniques of crystal growth involving multiple temperature zones such as vapor transport experiments and other materials science experiments. The five zones are primarily designed to produce uniform hot and cold temperature regions separated by an adiabatic region constructed of a heat extraction plate and an insert to reduce radiation from the hot to the cold zone. The hot and cold zone temperatures are designed to reach 1600 C and 1100 C, respectively. AADSF operates on a Multi-Purpose Experiment Support Structure (MPESS) within the cargo bay of the Space Shuttle on the United States Microgravity Payload (USMP) missions. Two successful flights, both employing the directional solidification or Bridgman Stockbarger technique for crystal growth have been made, and crystals of HgCdTe and PbSnTe grown in microgravity have been produced on USMP-2 and USMP-3, respectively. The addition of a Sample Exchange Mechanism (SEM) will enable three different samples to be processed on future flights including the USMP-4 mission.

Gillies, D. C.↗
NASA NTRS2002

ISAIA: Interoperable Systems for Archival Information Access

The ISAIA project was originally proposed in 1999 as a successor to the informal AstroBrowse project. AstroBrowse, which provided a data location service for astronomical archives and catalogs, was a first step toward data system integration and interoperability. The goals of ISAIA were ambitious: '...To develop an interdisciplinary data location and integration service for space science. Building upon existing data services and communications protocols, this service will allow users to transparently query hundreds or thousands of WWW-based resources (catalogs, data, computational resources, bibliographic references, etc.) from a single interface. The service will collect responses from various resources and integrate them in a seamless fashion for display and manipulation by the user.' Funding was approved only for a one-year pilot study, a decision that in retrospect was wise given the rapid changes in information technology in the past few years and the emergence of the Virtual Observatory initiatives in the US and worldwide. Indeed, the ISAIA pilot study was influential in shaping the science goals, system design, metadata standards, and technology choices for the virtual observatory. The ISAIA pilot project also helped to cement working relationships among the NASA data centers, US ground-based observatories, and international data centers. The ISAIA project was formed as a collaborative effort between thirteen institutions that provided data to astronomers, space physicists, and planetary scientists. Among the fruits we ultimately hoped would come from this project would be a central site on the Web that any space scientist could use to efficiently locate existing data relevant to a particular scientific question. Furthermore, we hoped that the needed technology would be general enough to allow smaller, more-focused community within space science could use the same technologies and standards to provide more specialized services. A major challenge to searching for data across a broad community is that information that describe some data products are either not relevant to other data or not applicable in the same way. Some previous metadata standard development efforts (e.g., in the earth science and library communities) have produced standards that are very large and difficult to support. To address this problem, we studied how a standard may be divided into separable pieces. Data providers that wish to participate in interoperable searches can support only those parts of the standard that are relevant to them. We prototyped a top-level metadata standard that was small and applicable to all space science data.

Hanisch, Robert J.↗
NASA NTRS2004

Space-based Science Operations Grid Prototype

Grid technology is the up and coming technology that is enabling widely disparate services to be offered to users that is very economical, easy to use and not available on a wide basis. Under the Grid concept disparate organizations generally defined as "virtual organizations" can share services i.e. sharing discipline specific computer applications, required to accomplish the specific scientific and engineering organizational goals and objectives. Grids are emerging as the new technology of the future. Grid technology has been enabled by the evolution of increasingly high speed networking. Without the evolution of high speed networking Grid technology would not have emerged. NASA/Marshall Space Flight Center's (MSFC) Flight Projects Directorate, Ground Systems Department is developing a Space-based Science Operations Grid prototype to provide to scientists and engineers the tools necessary to operate space-based science payloads/experiments and for scientists to conduct public and educational outreach. In addition Grid technology can provide new services not currently available to users. These services include mission voice and video, application sharing, telemetry management and display, payload and experiment commanding, data mining, high order data processing, discipline specific application sharing and data storage, all from a single grid portal. The Prototype will provide most of these services in a first step demonstration of integrated Grid and space-based science operations technologies. It will initially be based on the International Space Station science operational services located at the Payload Operations Integration Center at MSFC, but can be applied to many NASA projects including free flying satellites and future projects. The Prototype will use the Internet2 Abilene Research and Education Network that is currently a 10 Gb backbone network to reach the University of Alabama at Huntsville and several other, as yet unidentified, Space Station based science experimenters. There is an international aspect to the Grid involving the America's Pathway (AMPath) network, the Chilean REUNA Research and Education Network and the University of Chile in Santiago that will further demonstrate how extensive these services can be used. From the user's perspective, the Prototype will provide a single interface and logon to these varied services without the complexity of knowing the where's and how's of each service. There is a separate and deliberate emphasis on security. Security will be addressed by specifically outlining the different approaches and tools used. Grid technology, unlike the Internet, is being designed with security in mind. In addition we will show the locations, configurations and network paths associated with each service and virtual organization. We will discuss the separate virtual organizations that we define for the varied user communities. These will include certain, as yet undetermined, space-based science functions and/or processes and will include specific virtual organizations required for public and educational outreach and science and engineering collaboration. We will also discuss the Grid Prototype performance and the potential for further Grid applications both space-based and ground based projects and processes. In this paper and presentation we will detail each service and how they are integrated using Grid

Bradford, Robert N.↗
NASA NTRSDate not supplied

Technology Assessment for Producing Propellant From Lunar Water

Introduction: The presence of water ice in permanently shadowed regions (PSRs) on the lunar surface may enable a sustained human presence on the Moon with minimal need for consumables. One of the most valuable uses of lunar water is to produce rocket propellant. A sustained human presence on the Moon will re-quire frequent launches from the lunar surface, and each launch will require tons of propellant. However, many other volatiles are likely to be present in the areas where lunar water is stable1. Producing propellant from lunar water in-situ will require the separation and purification of water before it can be electrolyzed into oxygen and hydrogen gas. The Resource Exploration and Science of OUR Cosmic Environment (RESOURCE) project, funded by the Solar System Exploration Research Virtual Institute (SSERVI) program, includes a task to demonstrate the end-to-end process of water extraction, capture, purification and electrolysis to produce pure/dry oxygen gas sourced from an icy regolith mixture. Water Purification: The requirements for water purity are driven by the type of water electrolyzer used. For example, the water electrolyzer currently used on the International Space Station is based on proton ex-change membrane (PEM) technology. PEM-based electrolyzers require water to be ultrapure and deionized (>10 MegaOhm-cm) so that electrical conductivity is limited to the membranes themselves, where electrical current is used to convert H2O into H2 and O2.. A practical first step toward purifying water that is sourced from a lunar PSR is to use freeze distillation to separate water from other volatiles2. A sub-micronic filter can also be used to ensure that a minimal amount of dust is present in any lunar water that is captured. The combination of freeze distillation and sub-micronic filtration will result in relatively pure water but would require a deionization step if being fed into a PEM electrolyzer. Water Electrolysis: An alternative to PEM electrolysis is to use a Solid Oxide Electrolyzer (SOE). This technology operates at a much higher operating temperature (~800oC) and has a limited pressure range but does not require water to be ultrapure and deionized. Another advantage of SOE technology is that it produces pure dry oxygen gas without the need of an additional drying step. PEM electrolyzers produce humid oxygen gas and the humidity must be removed prior to liquefaction. Assessment: In order to compare PEM and SOE technologies side-by-side, they must be compared at a system level that includes water purification and gas drying steps. Engineers at the Johnson Space Center up-dated and utilized a detailed In-Situ Resource Utilization (ISRU) system model to compare and select the best option for the RESOURCE project which will conclude with a laboratory demonstration of the process of producing pure/dry oxygen from an icy regolith mixture in 2025.

A.J. Paz↗