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The design and evaluation of a Vacuum-Swing Adsorption (VSA) system to remove metabolic water and metabolic carbon dioxide from a spacecraft atmosphere is presented. The approach for Orion and Altair is a VSA system that removes not only 100 percent of the metabolic CO2 from the atmosphere, but also 100% of the metabolic water as well, a technology approach that has not been used in previous spacecraft life support systems. The design and development of an Orion Crew Exploration Vehicle Sorbent Based Atmosphere Revitalization system, including test articles, a facility test stand, and full-scale testing in late 2008 and early 2009 is discussed.

Developmental efforts are seeking to improve upon the efficiency and reliability of typical packed beds of sorbent pellets by using structured sorbents and alternative bed configurations. The benefits include increased structural stability gained by eliminating clay bound zeolite pellets that tend to fluidize and erode, and better thermal control during sorption leading to increased process efficiency. Test results that demonstrate such improvements are described and presented.

The design of a vacuum-swing adsorption process to remove metabolic water, metabolic carbon dioxide, and metabolic and equipment generated trace contaminant gases from the Orion Crew Exploration Vehicle (CEV) atmosphere is presented. For Orion, the approach is taken that all metabolic water must be removed by the Sorbent-Based Atmosphere Revitalization System (SBAR), a technology approach that has not been used in previous spacecraft life support systems. Design and development of a prototype SBAR, a facility test stand, and subsequent testing of the SBAR in late 2006 and early 2007 is discussed.

In-situ production of oxygen and methane for utilization as a return propellant from Mars for both sample-return and manned missions is currently being developed by NASA in cooperation with major aerospace companies. Various technologies are being evaluated using computer modeling and analysis at the system level. An integrated system that processes the carbon dioxide in the Mars atmosphere to produce liquid propellants has been analyzed. The system is based on the Sabatier reaction that utilizes carbon dioxide and hydrogen to produce methane and water. The water is then electrolyzed to produce hydrogen and oxygen. While the hydrogen is recycled, the propellant gases are liquefied and stored for later use. The process model considers the surface conditions on Mars (temperature, pressure, composition), energy usage, and thermal integration effects on the overall system weight and size. Current mission scenarios require a system that will produce 0.7 kg of propellant a day for 500 days.

In the closed environment of an inhabited spacecraft, a critical aspect of the air revitalization system is the removal of the carbon dioxide (CO2) and water vapor produced by the crew. A number of different techniques can be used for CO2 removal, but current methods are either non-regenerative or require a relatively high power input for thermal regeneration. Two-bed CO2 adsorption systems that can remove CO2 from humid air and be regenerated using pressure-swing desorption offer mass, volume, and power advantages when compared with the other methods. Two classes of sorbent materials show particular promise for this application: Zeolite sorbents, similar to those in the International Space Station (ISS) CO2 removal assembly Functionalized carbon molecular sieves (FCMS), which adsorb CO2 independent of the humidity in the airstream Pressure-swing testing of these two different sorbents under both space station and space suit conditions are currently underway.

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 Lunar-Mars Life Support Test Project (LMLSTP), formerly known as the Early Human Testing Initiative (EHTI), was established to perform the necessary research, technology development, integration, and verification of regenerative life support systems to provide safe, reliable, and self-sufficient human life support systems. Four advanced life support system test phases make up LMLSTP. Phase I of the test program demonstrated the use of plants to provide the atmosphere revitalization requirements of a single test subject for 15 days. The primary objective of the Phase II test was to demonstrate an integrated regenerative life support system capable of sustaining a human crew of four for 30 days in a closed chamber. The third test phase, known as Phase IIA, served as a demonstration of International Space Station (ISS) representative life support technology, supporting a human crew of four for 60 days.

Space environmental control systems must control cabin temperature and humidity. This can be achieved by transferring the heat load to a circulating coolant, condensing the humidity, and separating the condensate from the air stream. In addition, environmental control systems may be required to remove particulate matter from the air stream. An assembly comprised of a filter, a condensing heat exchanger, a thermal control valve, and a liquid carryover sensor, is used to achieve all these requirements. A condensing heat exchanger and filter assembly (CHXFA) is being developed and manufactured by SECAN/AlliedSignal under a contract from Dornier Daimler-Benz as part of a European Space Agency program. The CHXFA is part of the environmental control system of the Columbus Orbital Facility (COF), the European laboratory module of the International Space Station (ISS).

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.

The Lunar-Mars Life Support Test Project (LMLSTP) Phase III test examined the use of biological and physicochemical life support technologies for the recovery of potable water from waste water, the regeneration of breathable air, and the maintenance of a shirt-sleeve environment for a crew of four persons for 91 days. This represents the longest duration ground-test of life support systems with humans performed in the United States. This paper will describe the test from the inside viewpoint, concentrating on three major areas: maintenance and repair of life support elements, the scientific projects performed primarily in support of the International Space Station, and numerous activities in the areas of public affairs and education outreach.

The design of a Vacuum-Swing Adsorption (VSA) system to remove metabolic water and metabolic carbon dioxide from the Orion Crew Exploration Vehicle (CEV) atmosphere is presented. The approach for Orion is a VSA system that removes not only 100 percent of the metabolic CO2 from the atmosphere, but also 100% of the metabolic water as well, a technology approach that has not been used in previous spacecraft life support systems. The design and development of the Sorbent Based Atmosphere Regeneration (SBAR) system, including test articles, a facility test stand, and full-scale testing in late 2007 and early 2008 is discussed.

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.

Although designed to remove organic contaminants from a variety of wastewater streams, the planned U.S. and present Russian-provided water processing systems on board the International Space Station (ISS) have capacity limits for some of the more common volatile cleaning solvents used for housekeeping purposes. Using large quantities of volatile cleaning solvents during the ground processing and in-flight operational phases of a crewed spacecraft such as the ISS can lead to significant challenges to the water processing systems. To understand the challenges facing the management of water processing capacity, the relationship between cabin atmospheric quality and humidity condensate loading is presented. This relationship is developed as a tool to determine the cabin atmospheric loading that may compromise water processing system performance.

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 design of a vacuum-swing adsorption process to remove metabolic water, metabolic carbon dioxide, and metabolic and equipment generated trace contaminant gases from the crew exploration vehicle (CEV) atmosphere is presented. For the CEV, the sorbent-based atmosphere revitalization (SBAR) system must remove all metabolic water, a technology approach that has not been used in previous spacecraft life support systems. Design and development of a prototype SBAR, a full scale and subscale facility test stand, and other aspects of the SBAR development program is discussed.

A series of tests has been conducted at the NASA Marshall Space Flight Center (MSFC) to evaluate the performance of the Space Station Freedom (SSF) water recovery system. Potable and urine reclamation processors were integrated with waste water generation equipment and successfully operated for a total of 144 days. This testing marked the first occasion in which the waste feed sources for previous potable and hygiene loops were combined into a single loop and processed to potable water quality. Reclaimed potable water from the combined waste waters routinely met the SSF water quality specifications. In the last stage of this testing, data was obtained that indicated that the Water Processor (WP) presterilizer may not be required to meet the potable water quality specification.

One of the primary safety concerns for Space Station Freedom pressurized modules is fire. Some Freedom modules are unattended for long periods of time. In other cases, enclosed, pressurized volumes are not open to crew monitoring. As a result, a fire detection system is required to continuously monitor all modules for combustion. This paper briefly reviews the overall design for the Freedom fire detection system, and the design of the two basic types of detectors: smoke and flame. The smoke detectors monitor particulates in small open areas, stand-offs, end-cones, and racks. The flame detectors survey open areas for radiation at wavelengths and intensities characteristic of combustion. Responses from detectors are evaluated by Freedom's data management system to determine the presence of combustion and to recommend appropriate action.