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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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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Dimethylsilanediol (DMSD) Source Assessment and Mitigation on ISS: Estimated Contributions from Personal Hygiene Products Containing Volatile Methyl Siloxanes (VMS)

Dimethylsilanediol (DMSD) is a small organosilicon compound present in humidity condensate on the International Space Station. Aqueous DMSD originates from volatile methyl siloxane (VMS) compounds in the ISS cabin atmosphere. DMSD is not effectively removed by the WPA (Water Processor Assembly), requiring removal and replacement of both WPA Multifiltration (MF) Beds for an estimated resupply penalty of approximately 70 kg/year. Analyses indicate that WPA can handle DMSD if the concentration in the condensate can by reduced by fifty percent. Personal Hygiene Products (PHPs) used by crew are suspected to be a significant source of VMS. Source removal of VMS will be required to achieve a measurable impact to the DMSD concentration in the condensate. The inventory of total crew provisions for ISS was analyzed to identify silicon containing materials and products used for personal hygiene that emit VMS. Accounting for the wide range in mass of hygiene product applied to skin or hair, the frequency of application, the product selection, the number of crew using a given product, the range in silicon mass fraction of different products, and the potential vaporization of the product, the potential total VMS emissions from personal hygiene products for a crew of six on ISS were estimated. The total daily VMS emissions from PHPs estimate ranges from 261 to 1145 mg-Si per day, compared to total estimated VMS generation rates on ISS of 800 to 1500 mg-Si per day. The main sources of VMS were determined to be antiperspirants (173 to 696 mg-Si per day), skin lotions (63 to 248 mg-Si per day), wipes (25 to 124 mg-Si per day) and hair conditioner (0 to 69 mg-Si per day). Several siloxanes-free options are available for deodorants, wet wipes, lotions, and leave-in conditioners. These products are now being assessed for crew member use in future increments.

Muirhead, Dean L.↗
NASA NTRS2019

Electrochemical Solutions for Advanced Life Support

The Oxygen Generating Assembly (OGA) on-board the International Space Station (ISS) employs a polymer electrolyte membrane (PEM) water electrolysis cell stack to electrochemically dissociate water into its two components – oxygen and hydrogen. Oxygen is provided to the cabin atmosphere for crew respiration while the hydrogen is delivered to a carbon dioxide reduction system to recover oxygen as water. The design of the OGA evolved over a number of years to arrive at the system solution that is currently operational on ISS. Future manned missions to space will require advanced technologies that eliminate the need for resupply from earth and feature in-situ resource utilization to sustain crew life and to provide useful materials to the crew. The architects planning such missions should consider all potential solutions at their disposal to arrive at an optimal vehicle solution that minimizes crew maintenance time, launch weight, installed volume and energy consumption demands. Skyre is developing new technologies through funding from NASA, the Department of Energy, and internal investment based on PEM technology that could become an integral part of these new vehicle solutions. At varying stages of Technology Readiness Level (TRL) are: an oxygen concentrator and compressor that can separate oxygen from an air stream and provide an enriched oxygen resource for crew medical use and space suit recharge without any moving parts in the pure oxygen stream; a regenerative carbon dioxide removal system featuring a PEM-based sorbent regenerator; a carbon dioxide reduction system that electrochemically produces organic compounds that could serve as fuels or as a useful intermediary to more beneficial compounds; and an electrochemical hydrogen separator and compressor for hydrogen recycle. The technical maturity of these projects is presented along with pertinent performance test data that could be beneficial in future study efforts.

Roy, Robert J.↗
NASA NTRSDate not supplied

The Integrated Carbon Dioxide Removal, Compression, andStorage (CRCS) System

The Carbon Dioxide Removal, Compression, and Storage (CRCS) system was designed to remove carbondioxide (CO2(g)) from the spacecraft cabin atmosphere and compress and store the CO2(g) for furtherprocessing. Previous conference papers describe the hardware design and functional testing of the single anddual beds. This paper discusses the integrated system test results when dry CO2(g) latent air (2600ppm CO2(g))enters the system at 30 SCFM.

air revitalization↗
NASA NTRSDate not supplied

Aerosol Physics for the Lunar Environment: Equations for Lunar Dust Control and Mitigation Technologies

Sticky and jagged dust was ubiquitous during the Apollo missions, causing soiling and abrasion problems with seals, coatings and equipment, in addition to eye irritation and breathing discomfort in the cabin. The Artemis Program of NASA aims to place astronauts on the lunar surface by 2024 and establish a sustainable presence in the following decade. Returning to the Moon requires controlling and mitigating the dust which will be inevitably brought inside the cabins. The state-of-the-science for effective collection of aerosols is based on dynamics of airborne particulate matter under terrestrial conditions. However, the governing physics does not apply to extra-vehicular activity in the hard-vacuum lunar condition. For example, the substantial difference in gravity will dictate particle transport both outside and inside the cabin. In this study, we revisited the aerosol physical phenomena that are assumed in the design of Earth-based aerosol instruments and extend the applicability to different scenarios in lunar missions. As shown, long-term lunar habitats, transfer vehicles to lunar orbital platforms, and low pressure cabin atmospheres have different aerosol dynamics. In all cases, the impact of dust control strategies using gravitational, electrical, and thermal techniques for various mitigation and monitoring hardware is explored. The guidelines provided through this study will show how terrestrial aerosol equipment can translate to lunar dust applications.

Nima Afshar-Mohajer↗
NASA NTRS2022

Gas Trap Plug Design, Function and Performance

The cooling loops of the Internal Active Thermal Control System (IATCS) on the Node 3, Node 2 and US Laboratory (USL) Modules of the International Space Station (ISS) have been serviced by Gas Traps (GTs) since the onset of operations. These traps serve to protect the pumping function of the cooling loops by eliminating free gas that would otherwise impact the impellers and cause a loop shutdown. Gas Trap Plug Assemblies (GTPAs) have been designed, manufactured and tested, to permit function of the IATCS in the event of a loss of cabin atmosphere and long term decrew event. The GTPA also serve to give the crew additional time to evacuate the United States Operating Segment (USOS) in the unlikely event of an Ammonia breach of an Interface Heat Exchanger (IFHX). These GTPAs have been installed on the ISS IATCS since May 2019. This paper will address purpose, design and testing of the GTPA. The paper will also provide analyses showing residual trapping capability and free gas elimination of the GTs even while tightly plugged, for both the GTs and the Alternate Gas Trap Assemblies (AGTAs) ground spares.

Gas Trap Plugs↗
NASA NTRSDate not supplied

Validation of Decompression Sickness Risk Mitigation Protocols for Planetary Spaceflight Missions

BACKGROUND: Apollo missions used a 100% O2 cabin atmosphere which effectively eliminated the risk of decompression sickness (DCS) during extravehicular activity (EVA) on the moon. NASA’s future missions to the moon and Mars are expected to use nitrox gas mixtures of up to 34% O2, 66% N2, which will reduce flammability risk compared with Apollo, but will necessitate Oxygen prebreathe prior to EVA to reduce DCS risk to acceptable levels. Prebreathe protocols used on the space shuttle and International Space Station are validated for microgravity EVAs, but the significantly increased risk of DCS during equivalent ambulatory EVAs make these protocols inapplicable to planetary EVA. An “exploration atmosphere” of 56.5 kPa (8.2 psia), 34% O2, 66% N2 has been recommended by NASA as a compromise that balances prebreathe duration, hypoxia, and flammability risk, assuming a 29.6 kPa (4.3 psi) spacesuit. However, this atmosphere may not be used for vehicles that do not support frequent EVA, and with commercial providers and international providers expected to provide landers, pressurized rovers, habitats, and spacesuits, different combinations of vehicle and spacesuit atmospheres are possible and will each require validated prebreathe protocols. OVERVIEW: Key components of a multi-year strategic roadmap include: 1) Establish hypobaric chamber facility capable of supporting 8-person EVA prebreathe validation tests at saturation atmospheres up to 36% O2; 2) validate an EVA physical workload simulation for use during prebreathe validation testing; 3) validate the recommended “exploration atmosphere” prebreathe protocol; 4) validate prebreathe protocols for additional atmospheric combinations that bound the most likely potential operating ranges of future vehicles and spacesuits; and 5) update DCS risk estimation models based on results of prebreathe validation studies. DISCUSSION: Details and data from completion of the first two steps of the strategic roadmap will be presented; the third step is currently underway, with pilot results provided in a companion presentation. Steps four and five will require a multi-year series of chamber tests; collaborations are being pursued.

Andrew F. J. Abercromby↗
NASA NTRSDate not supplied

Modeling the Integrated Thermal Amine Scrubber and Air Cooled-Temperature Swing Adsorbent Compressor

As part of a larger CO2 removal architecture study, a model was developed in Aspen Custom Modeler of the Thermal Amine Scrubber (TAS), an ISS flight experiment intended to scrub CO2 from the cabin air. In order to minimize mass losses, it was determined the TAS should work in conjunction with the Air Cooled-Temperature Swing Adsorption Compressor (AC-TSAC) to reduce the CO2 for O2 production. First the TAS removes CO2 from the cabin atmosphere, then the AC-TSAC compresses the CO2 and feeds it in a steady steam to a Sabatier or Bosch process. This document details an effort to add a model of the AC-TSAC to the existing TAS model to determine if the two hardware systems will have deleterious effects on each other’s performance. It was found the AC-TSAC provided sufficient vacuum for the TAS’s desorption to occur, but not the same level of vacuum as space vacuum. This lower quality vacuum led to a reduction in the total cyclical uptake capacity of the TAS and thus a lower CO2 removal under the same conditions. The TAS did not remove enough CO2 to fill the AC-TSAC bed to capacity during the production phase which caused the AC-TSAC to run out of CO2 during production. This renders the addition of the AC-TSAC pointless. It is believed these effects can be overcome with a redesign of one or both systems.

TAS↗
NASA NTRS2026

Designing a Propylene-Glycol Coolant Servicer System for Gateway’s Internal Active Thermal Control System

A human spacecraft ATCS—especially one using single-phase coolant loops exposed to cabin atmospheric conditions—requires periodic degassing and refilling to support long-duration missions of 15 to 30 years. During initial fill operations, system maintenance, gas permeation, and quick-disconnect mating or de-mating, small amounts of gas can gradually enter the coolant system over time. This can lead to degraded heat transfer performance, pump cavitation, and potentially pump vapor lock if a significant gas volume accumulates over time. Additionally, system leaks and routine fluid sampling can gradually reduce accumulator volumes to unacceptable levels, requiring periodic refills. In more severe cases, catastrophic changes in fluid composition may necessitate emergency draining, refilling, and degassing to ensure continued system functionality. These risks were identified and mitigated on the ISS ITCS through the development of a dual-membrane degasser ORU and a Fluid Servicer System ORU for coolant refilling. These systems were developed for the fully water-based ISS ITCS Coolant[1]. The Gateway space station, the first permanent human habitat in lunar orbit, uses a propylene-glycol/water coolant mixture, which has significantly different fluid properties compared to pure water. Because microgravity degassing technologies are sensitive to fluid surface tension and viscosity, existing ISS hardware is not suitable for servicing a propylene-glycol-based TCS. Unlike the ISS, the Gateway will operate in a higher-radiation environment and must meet stricter mass constraints due to its location outside of low earth orbit. This Government Furnished Equipment (GFE) flight hardware project aims to develop a lightweight, radiation-resistant Coolant Servicer System (CSS) capable of degassing and refilling Gateway’s propylene-glycol water-based IATCS.

Propylene Glycol Water↗
NASA NTRS2026

Designing a Propylene-Glycol Coolant Servicer System for Gateway’s Internal Active Thermal Control System

A human spacecraft ATCS—especially one using single-phase coolant loops exposed to cabin atmospheric conditions—requires periodic degassing and refilling to support long-duration missions of 15 to 30 years. During initial fill operations, system maintenance, gas permeation, and quick-disconnect mating or de-mating, small amounts of gas can gradually enter the coolant system over time. This can lead to degraded heat transfer performance, pump cavitation, and potentially pump vapor lock if a significant gas volume accumulates over time. Additionally, system leaks and routine fluid sampling can gradually reduce accumulator volumes to unacceptable levels, requiring periodic refills. In more severe cases, catastrophic changes in fluid composition may necessitate emergency draining, refilling, and degassing to ensure continued system functionality. These risks were identified and mitigated on the ISS ITCS through the development of a dual-membrane degasser ORU and a Fluid Servicer System ORU for coolant refilling. These systems were developed for the fully water-based ISS ITCS Coolant[1]. The Gateway space station, the first permanent human habitat in lunar orbit, uses a propylene-glycol/water coolant mixture, which has significantly different fluid properties compared to pure water. Because microgravity degassing technologies are sensitive to fluid surface tension and viscosity, existing ISS hardware is not suitable for servicing a propylene-glycol-based TCS. Unlike the ISS, the Gateway will operate in a higher-radiation environment and must meet stricter mass constraints due to its location outside of low earth orbit. This Government Furnished Equipment (GFE) flight hardware project aims to develop a lightweight, radiation-resistant Coolant Servicer System (CSS) capable of degassing and refilling Gateway’s propylene-glycol water-based IATCS.

Propylene Glycol Water↗
NASA NTRS1978

Ozone concentration in the cabin of a Gates Learjet measured simultaneously with atmospheric ozone concentrations

A Gates Learjet Model 23 was instrumented with monitors to measure simultaneously the atmospheric and the cabin concentrations of ozone at altitudes up to 13 kilometers. Six data flights were made in February 1978. Results indicated that only a small amount of the atmospheric ozone is destroyed in the cabin pressurization system. Ozone concentrations measured in the cabin near the conditioned-air outlets were only slightly lower than the atmospheric ozone concentration. For the two cabin configurations tested, the ozone retention in the cabin was 63 and 41 percent of the atmospheric ozone concentration. Maximum cabin ozone concentration measured during these flights was 410 parts per billion by volume.

Briehl, D.↗
NASA NTRS1964

Closed atmospheres

Simulation of closed atmospheres for space flights

SPACE CABIN ATMOSPHERE↗