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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.

Shortly after installation of the service and performance heat exchanger (SPCU HX) in 2001, samples collected from the coolant fluid indicated the presence of nickel accompanied by a subsequent decrease in phosphate concentration along with a high microbial load. When the SPCU HX was replaced and evaluated post-flight, it was expected that the heat exchanger would have significant biofilm and corrosion present given the composition of the coolant fluid; however, there was no evidence of either. Early results from two experiments imply that the heat exchanger materials themselves are inhibiting biofilm formation. This paper discusses the results of one set of experiments and puts forward the inhibition of quorum sensing as a possible mechanism for the lack of biofilm formation.

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 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 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.

A three-year program to develop a Direct Drive Hall Effect Thruster (D2HET) system began 15 months ago as part of the NASA Advanced Cross-Enterprise Technology Development initiative. The system is expected to reduce significantly the power processing, complexity, weight, and cost over conventional low-voltage systems. The D2HET will employ solar arrays that operate at voltages greater than 300V, and will be an enabling technology for affordable planetary exploration. It will also be a stepping-stone in the production of the next generation of power systems for Earth orbiting satellites. This paper provides a general overview of the program and reports the first year's findings from both theoretical and experimental components of the program.

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.

Spacelab mission thermal integration is one of many activities performed at the NASA Marshall Space Flight Center (MSFC). The Spacelab carrier system has been expanded from the original module/pallet system. Thermodynamics and heat transfer as well as fluid mechanics and fluid dynamics are the support areas discussed here. This support incorporates preflight mission analysis in conjunction with real time mission support and postflight mission analysis. This paper summarizes these activities for the Spacelab carrier complement, citing some of the more challenging thermal control designs for which the Center is and has been responsible. Technology advancements, coupled with the ever increasing needs of the payload community and the desire for flexibility to manifest several distinct payload elements on a single mission, has aided in the evolution of a more diverse Spacelab carrier complement.

Nickel-hydrogen (Ni-H2) technology has only recently been utilized in low earth orbit (LEO) applications. The Hubble Space Telescope (HST) program, over the past five years, played a key role in developing this application. The HST not only became the first reported, nonexperimental program to fly Ni-H2 batteries in a LEO application, but funded numerous, ongoing tests that served to validate this usage. The Marshall Space Flight Center (MSFC) has been testing HST Ni-H2 batteries and cells for over three years. The major tests include a 6-battery system (SBS) test and a single 22-cell battery (FSB) test. The SBS test has been operating for 34 months and completed approximately 15,200 cycles. The performance of the cells and batteries in this test is nominal. Currently, the batteries are operating at an average end-of-charge (EOC) pressure that indicates an average capacity of approximately 79 ampere-hours (Ah).

The Russian space program has maintained crews on long duration space flights nearly continuously over the past two decades. As a result, a strong emphasis has been placed on the development of regenerative life support systems. One of these systems is a urine processor which has been operating on-orbit since 1990. The U. S has also been developing urine processing systems to reclaim water from urine over the past twenty years. This paper will describe the two different technologies used for urine processing for long-term human presence in space and will compare the operating characteristics of the two systems.

The baseline Environmental Control and Life Support System (ECLSS) for the International Space Station (ISS) includes regenerative and non-regenerative technologies for Temperature and Humidity Control (THC), Atmosphere Control and Supply (ACS), Fire Detection and Suppression (FDS), Atmosphere Revitalization (AR), Water Recovery and Management (WRM), Waste Management (WM), and Vacuum System (VS). The U.S. Lab module will contain complete THC and ACS subsystems and an open loop AR including a Carbon Dioxide Removal Assembly (CDRA), Trace Contaminant Control Subassembly (TCCS), and a Major Constituent Analyzer (MCA). An Oxygen Generation Assembly (OGA) is added with the U. S. Hab module, along with the WRM and WM subsystems. The final baseline configuration is a closed water loop and partially closed atmosphere loop and represents the best available mature technologies.

The appropriate role of human testing in life support systems design has been a key concern for human spacecraft development. This discussion intensified over the past one and a half years as the International Space Station (ISS) evaluated the risk associated with the baseline program while conducting cost and schedule convergence activities. The activity was carried from the traditional top-level discussion to evaluation of the specific Space Station Life Support concerns associated with human interaction, weighed against cost impacts. This paper details the results of this activity, providing the rationale for the present ISS approach.

A trade study conducted in 2001 selected a rotary disk separator as the best candidate to meet the requirements for an International Space Station (ISS) Carbon Dioxide Reduction Assembly (CRA). The selected technology must provide micro-gravity gas/liquid separation and pump the liquid from 69 kPa (10 psia) at the gas/liquid interface to 124 kPa (18 psia) at the wastewater bus storage tank. The rotary disk concept, which has pedigree in other systems currently being built for installation on the ISS, failed to achieve the required pumping head within the allotted power. The separator discussed in this paper is a new design that was tested to determine compliance with performance requirements in the CRA. The drum separator and pump (DSP) design is similar to the Oxygen Generator Assembly (OGA) Rotary Separator Accumulator (RSA) in that it has a rotating assembly inside a stationary housing driven by a integral internal motor[1].

An important aspect of air revitalization for life support in spacecraft is the removal of carbon dioxide from cabin air. Several types of carbon dioxide removal systems are in use or have been proposed for use in spacecraft life support systems. These systems rely on various removal techniques that employ different architectures and media for scrubbing CO2, such as permeable membranes, liquid amine, adsorbents, and absorbents. Sorbent systems have been used since the first manned missions. The current state of key technology is the existing International Space Station (ISS) Carbon Dioxide Removal Assembly (CDRA), a system that selectively removes carbon dioxide from the cabin atmosphere. The CDRA system was launched aboard UF-2 in February 2001 and resides in the U.S. Destiny Laboratory module. During the past four years, the CDRA system has experienced operational limitations.

This paper presents and discusses the results of an integrated 4-Bed Molecular Sieve (4BMS), mechanical compressor, and Sabatier Engineering Development Unit (EDU) test. Testing was required to evaluate the integrated performance of these components of a closed loop atmosphere revitalization system together with a proposed compressor control algorithm. A theoretical model and numerical simulation had been used to develop the control algorithm; however, testing was necessary to verify the simulation results and further refine the model. Hardware testing of a fully integrated system also provided a better understanding of the practical inefficiencies and control issues, which are unavailable from a theoretical model.

The toxicity test method utilized by The National Aeronautics and Space Administration (NASA) is being modified to create an International Standard. The method, NHB 8060.1 C, Test 7, is utilized to determine the identity and quantity of offgassed products from materials and hardware. This paper focuses on the resolution of technical issues faced during its transition from a US specific document to an International Standard. NASA, the European Space Agency (ESA) and the National Space Development Agency of Japan (NASDA) have been very active in bringing ISO 14624-3 through several revisions to its current form. It is anticipated that the document could be an international standard by the end of 1999, with the full support of NASA, ESA, NASDA, and the other national programs represented in Working Group 1.