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The Vapor Phase Catalytic Ammonia Removal (VPCAR) technology has been previously discussed as a viable option for the Exploration Water Recovery System. This technology integrates a phase change process with catalytic oxidation in the vapor phase to produce potable water from exploration mission wastewaters. A developmental prototype VPCAR was designed, built and tested under funding provided by a National Research Announcement (NRA) project. The core technology, a Wiped Film Rotating Device (WFRD) was provided by Water Reuse Technologies under the NRA, whereas Hamilton Sundstrand Space Systems International performed the hardware integration and acceptance test of the system. Personnel at the Ames Research Center performed initial systems test of the VPCAR using ersatz solutions. To assess the viability of this hardware for Exploration Life Support (ELS) applications, the hardware has been modified and tested at the MSFC ECLS Test Facility.

Spacecraft hardware trade studies compare options primarily on mass while considering impacts to cost, risk, and schedule. Historically, other factors have been considered in these studies, such as reliability, technology readiness level (TRL), volume and crew time. In most cases, past trades compared two or more technologies across functional and TRL boundaries, which is an uneven comparison of the technologies. For example, low TRL technologies with low mass were traded directly against flight-proven hardware without consideration for requirements and the derived architecture. To provide for even comparisons of spacecraft hardware, trades need to consider functionality, mission constraints, integer vs. real number of flight hardware units, and mass growth allowances by TRL.

We present the development of a semiconductor diode laser spectral absorption based gas species sensor for oxygen concentration measurements, intended for life support system monitoring and control applications. Employing a novel self-compensating, noise cancellation detection approach, we experimentally demonstrate better than 1% accuracy, linearity, and stability for monitoring breathing air conditions with 0.2 second response time. We also discuss applications of this approach to CO2 sensing.

The dual membrane gas trap filter is utilized in the internal thermal control system (ITCS) as part of the pump package assembly to remove non-condensed gases from the ITCS coolant. This improves pump performance and prevents pump cavitation. The gas trap also provides the capability to vent air that is Ingested into the ITCS during routine maintenance and replacement of the International Space Station (ISS) system orbital replacement units. The gas trap is composed of two types of membranes that are formed into a cylindrical module and then encased within a titanium housing. The non-condensed gas that is captured is then allowed to escape through a vent tube in the gas trap housing.

Advanced life support flight experiments have been conceptualized for the International Space Station (ISS). Two of the experiments, a high pressure oxygen generator and a carbon dioxide reduction subsystem, offer high payback potential to the ISS program. This paper documents the cost-benefit analyses for these two experiments.

A test has been completed at NASA's Marshall Space Flight Center (MSFC) to evaluate the Water Recovery and Management (WRM) system and Waste Management (WM) urinal design for the United States On-Orbit Segment (USOS) of the International Space Station (ISS). Potable and urine reclamation processors were integrated with waste water generation equipment and successfully operated for a total of 128 days in recipient mode configuration to evaluate the accumulation of contaminants in the water system and to assess the performance of various modifications to the WRM and WM hardware. No accumulation of contaminants were detected in the product water over the course of the recipient mode test. An additional 18 days were conducted in donor mode to assess the ability of the system to removal viral contaminants, to monitor the breakthrough of organic contaminants through the multifiltration bed, and for resolving anomalies that occurred during the test.

A two year test program has been initiated to evaluate the effects of extended duration operation on a solid polymer electrolyte Oxygen Generator Assembly (OGA); in particular the cell stack and membrane phase separators. As part of this test program, the OGA was integrated into the Marshall Space Flight Center (MSFC) Water Recovery Test (WRT) Stage 10, a six month test, to use reclaimed water directly from the water processor product water storage tanks. This paper will document results encountered and evaluated thus far in the life testing program.

Designers of future space vehicles envision simplifying the Atmosphere Revitalization (AR) system by combining the functions of trace contaminant (TC) control and carbon dioxide removal into one swing-bed system. Flow rates and bed sizes of the TC and CO2 systems have historically been very different. There is uncertainty about the ability of trace contaminant sorbents to adsorb adequately in a high-flow or short bed length configurations, and to desorb adequately during short vacuum exposures. This paper describes preliminary results of a comparative experimental investigation into adsorbents for trace contaminant control. Ammonia sorbents and low temperature catalysts for CO oxidation are the foci. The data will be useful to designers of AR systems for Constellation. Plans for extended and repeated vacuum exposure of ammonia sorbents are also presented.

The current dual-membrane gas trap is designed to remove non-condensed gases (NCG) from the Internal Thermal Control System (ITCS) coolant on board the International Space Station (ISS). To date it has successfully served its purpose of preventing depriming, overspeed, and shutdown of the ITCS pump. However, contamination in the ITCS coolant has adversely affected the gas venting rate and lifetime of the gas trap, warranting a development effort for a next-generation gas trap. Design goals are to meet or exceed the current requirements to (1) include greater operating ranges and conditions, (2) eliminate reliance on the current hydrophilic tube fabrication process, and (3) increase operational life and tolerance to particulate and microbial growth fouling.

A dual-membrane gas trap is currently used to remove non-condensed gases (NCG) from the Internal Thermal Control System (ITCS) coolant on board the International Space Station. The gas trap consists of concentric tube membrane pairs, comprised of outer hydrophilic tubes and inner hydrophobic fibers. Liquid coolant passes through the outer hydrophilic membrane, which traps the NCG. The inner hydrophobic fiber allows the trapped NCG to pass through and vent to the ambient atmosphere in the cabin. The purpose of the gas trap is to prevent gas bubbles from causing depriming, overspeed, and shutdown of the ITCS pump, and the current gas trap has performed flawlessly in this regard. However, because of actual operational conditions on-orbit, its gas removal performance and operational lifetime have been affected.

Significant erosion of preburner faceplates was observed during recent Space Shuttle Main Engine (SSME) test firings at the NASA Technology Test Bed (TTB), Marshall Space Flight Center (MSFC), Al. The OPAD instrumentation acquired exhaust plume spectral data during each test which indicate the occurrence of metallic species consistent with faceplate component composition. A qualitative analysis of the spectral data was conducted to evaluate the state of the engine versus time for each test according to the nominal conditions of TTB firing #17 and #18. In general the analyses indicate abnormal erosion levels at or near startup. Subsequent to the initial erosion event, signal levels tend to decrease towards nominal baseline values. These findings, in conjunction with post-test engine inspections, suggest that in cases under study, the erosion may not have been catastrophic to the immediate operation of the engine.

CO2 removal, recovery and reduction are essential processes for a closed loop air revitalization system in a crewed spacecraft. Typically, a compressor is required to recover the low pressure CO2 that is being removed from the spacecraft in a swing bed adsorption system. This paper describes integrated tests of a Temperature-Swing Adsorption Compressor (TSAC) with high-fidelity systems for carbon dioxide removal and reduction assemblies (CDRA and Sabatier reactor). It also provides details of the TSAC operation at various CO2 loadings. The TSAC is a solid-state compressor that has the capability to remove CO2 from a low-pressure source, and subsequently store, compress, and deliver it at a higher pressure. TSAC utilizes the principle of temperature-swing adsorption compression and has no rapidly moving parts.

The challenges of missions to the Moon and Mars presents NASA with the need for more advanced life support systems, including better technologies for CO2 removal in spacecraft atmospheres and extravehicular mobility units (EMU). Amine-coated single wall carbon nanotubes (SWCNT) have been proposed as a potential solution because of their high surface area and thermal conductivity. Initial research demonstrated the need for functionalization of SWCNT to obtain optimal adherence of the amine to the SWCNT support phase [1]. Recent efforts focus on the development of new methods to chemically bond amines to SWCNT. Synthesis and characterization methods for these materials are discussed and some preliminary materials characterization data are presented. The CO2 adsorption capacity for several versions of SWCNT supported amine-based CO2 scrubber materials is also determined.

At present, Nickel Hydrogen batteries are tested at Marshall Space Flight Center (MSFC) in support of the Hubble Space Telescope (HST) program. In previous years, Nickel Cadmium batteries were tested at MSFC in support of HST. The Nickel Cadmium Battery Expert System-2 (NICBES-2) was employed on the HST six battery test bed to evaluate the performance of the HST Electrical Power System (EPS). With the beginning of testing of the nickel hydrogen six battery test bed, NICBES-2 had to be converted to NICkel Hydrogen Battery Expert System (NICHES). This paper describes the conversion of the NICBES-2 to the NICHES as well as future plans for NICHES.

Life Sciences research on Space Station will utilize rats to study the effects of the microgravity environment on mammalian physiology and to develop countermeasures to those effects for the health and safety of the crew. The animals will produce metabolic water which must be reclaimed to minimize logistics support. The condensate from the Research Animal Holding Facility (RAHF) flown on Spacelab Life Sciences-2 (SLS-2) in October 1993 was used as an analog to determine the type and quantity of constituents which the Space Station (SS) water reclamation system will have to process. The most significant organics present in the condensate were 2-propanol, glycerol, ethylene glycol, 1,2-propanediol, acetic acid, acetone, total proteins, urea and caprolactam while the most significant inorganic was ammonia. Microbial isolates included Xanthomonas, Sphingobacterium, Pseudomonas, Penicillium, Aspergillus and Chrysosporium.

A program is being performed to design, fabricate, and test a metal hydride sorption cryocooler system capable of supplying periodic refrigeration at 10 K. The system is intended to cool a focal plane array for a low-earth orbit satellite. The refrigeration is effected by sublimating solid hydrogen at 10 K. The solid hydrogen is produced in a batch process by cooling, solidifying, and subcooling liquid hydrogen formed at 30 K by a Joule-Thomson expansion. The spent hydrogen from the sublimation and Joule-Thomson expansion is absorbed by two metal hydride sorption bed assemblies.

A test has been completed at NASA's Marshall Space Flight Center (MSFC) to evaluate the latest Water Recovery and Management (WRM) system and Waste Management (WM) urinal design for the United States On-Orbit Segment (USOS) of the International Space Station (ISS) with higher fidelity hardware and integration than has been achieved in previous integrated tests. Potable and urine reclamation processors were integrated with waste water generation equipment and successfully operated for a total of 116 days to evaluate the impacts of changes made as a result of the redesign from Space Station Freedom (SSF) to the ISS. This testing marked the first occasion in which the WRM was automated at the system level, allowing for evaluation of the hardware performance under ISS operating conditions. It was also the first time a “flight-like” Process Control Water Quality Monitor (PCWQM) and a WM urinal were tested in an integrated system.

This paper reviews designs of urine distillation systems for spacecraft water recovery. Consideration is given to both air evaporation and vacuum distillation cycles, to the means for improving cycle performance (such as heat pumps, multistaging, and rotary evaporators), and to system concepts offering promise for future development. Vacuum distillation offers lower power consumption, at some increase in system complexity; air evaporation distillation is capable of providing higher water recovery efficiency, which could offset the lower power consumption advantage of vacuum distillation for long-duration missions.

A regenerable metal oxide CO2 absorber is being developed for future Extravehicular Mobility Unit (EMU) applications. It was designed to fit the existing shuttle EMU without modification of the interfaces. Absorption and regeneration tests were performed with subscale and full-size laboratory absorbers. Data is presented for open and closed loop absorber tests that evaluate the effects of residence time, mass velocity, and internal temperature on performance, with emphasis is on the full-size test unit. Regeneration testing quantified the effects of temperature and air flow rate on desorption rate, and of various absorber cooling modes. Its objective was to optimize conditions for minimum peak power and minimum total energy consumption.

Eight SUMMA passivated sampling canisters were shipped to the Russian Space Station Mir in February of 1995 to assess ambient trace contaminant concentrations. Prior to flight, the canisters were injected with isotope labeled surrogates and internal standards to measure potential negative impacts on measurement accuracy caused by the trip environmental conditions of launch and return. Three duplicate canister samples were collected in parallel with Russian sorbent samples to acquire data for comparative purposes. A total of 32 target and 13 non-target volatile compounds were detected in each of the samples analyzed. The concentrations of the compounds remained relatively consistent for the three sampling events, and all of the concentrations of detected contaminants were well below both US and Russian Spacecraft Maximum Allowable Concentrations (SMAC). Five different fluorocarbons were consistently detected at relatively high concentrations.