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Vapor Compression Distillation (VCD) is the chosen technology for urine processing aboard the International Space Station (ISS). Development and life testing over the past several years have brought to the forefront problems and solutions for the VCD technology. Testing between 1992 and 1998 has been instrumental in developing estimates of hardware life and reliability. It has also helped improve the hardware design in ways that either correct existing problems or enhance the existing design of the hardware. The testing has increased the confidence in the VCD technology and reduced technical and programmatic risks. This paper summarizes the test results and changes that have been made to the VCD design.

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.

The assembly complete Environmental Control and Life Support (ECLS) system for the International Space Station (ISS) will consist of components and subsystems in both the U.S. and International partner elements which together will perform the functions of Temperature and Humidity Control (THC), Atmosphere Control and Supply (ACS), Atmosphere Revitalization (AR), Water Recovery and Management (WRM), Waste Management (WM), Fire Detection and Suppression (FDS), and Vacuum System (VS) for the station. Due to limited resources available on ISS, detailed attention is given to minimizing and tracking all resources associated with all systems, beginning with estimates during the hardware development phase through measured actuals when flight hardware is built and delivered. A comprehensive summary of resources consumed by the U.S.

The paper provides a summary of current work accomplished under technical task agreement (TTA) by the Marshall Space Flight Center (MSFC) regarding the Environmental Control and Life Support System (ECLSS) as well as future planning activities in support of the International Space Station(ISS).Current activities computer model development, component design and development, subsystem/integrated system testing, life testing, and government furnished equipment delivered to the ISS program. A long range plan for the MSFC ECLSS test facility is described whereby the current facility would be upgraded to support integrated station ECLSS operations. ECLSS technology development efforts proposed to be performed under the Advanced Engineering Technology Development (AETD) program are also discussed.

The International Space Station (ISS) modules Nodes 2 and 3 are progressing through the design phase into integration, test, and verification. This paper gives a status of the Nodes 2 and 3 Environmental Control and Life Support System (ECLSS) design progress since 1999 (ICES paper 1999-01-2146). The Node 2 Design Review 2 was completed in March 2001. Node 2 is currently in the hardware integration/test phase at Alenia Spazio. The ECLSS for Node 2 includes inter- and intramodule ventilation, temperature and humidity control, distribution of atmosphere samples, low pressure and recharge oxygen and nitrogen, fuel cell and wastewater, and fire detection and suppression. Changes/challenges since 1999 have included the addition of a low temperature loop coolant bypass around the Common Cabin Air Assembly condensing heat exchanger and resolution of common hardware and verification issues. The current status of hardware integration and testing is also 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.

Flight experiments are being developed to assess the microgravity performance of U.S.-developed physical/chemical life support technologies baselined for operation on the International Space Station (ISS). The experiments will take advantage of flight opportunities available on the Space Shuttle prior to the production of ISS flight systems. Early microgravity demonstrations of these technologies will allow the ISS life support system to be developed from flight-proven processes, thereby reducing programmatic risks and enhancing overall life support efficiencies. This paper will provide an overview of the life support flight experiment program.

This paper describes the development plan for a comprehensive research and diagnostic tool for aspects of advanced life support systems in space-based laboratories. Specifically, it aims to build a high fidelity tabletop model that can be used for the purpose of risk mitigation, failure mode analysis, contamination tracking, and testing reliability. The work envisions a comprehensive approach involving experimental work coupled with numerical simulation to develop this diagnostic tool. The use of an index matching fluid (fluid that matches the refractive index of cast acrylic, the model material) allows making the entire model (with complex internal geometry) transparent and hence conducive to non-intrusive optical diagnostics. Experimental and modeling work to date will be presented.

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.

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].

NASA - Marshall Space Flight Center has implemented fault injection into an electrical power system breadboard to study the reactions of the various control elements of this breadboard. Among the elements studied are the Remote Power Controllers (RPC), the algorithms in the control computers and the artificially intelligent control programs resident in this breadboard. To this end, a study of electrical power system faults was performed to yield a list of the most common power system faults. The results of this study were applied to a multichannel high voltage dc spacecraft power system called the Large Autonomous Spacecraft Electrical Power System Breadboard (LASEPS). The results of the study into the most common electrical power system faults was presented in two papers at this conference during the last two years;* the remainder of the results of this study are to be presented in this paper.

A dual-membrane gas trap is currently used to remove gas bubbles 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 gas bubbles. The inner hydrophobic fiber allows the trapped gas bubbles to pass through and vent to the ambient atmosphere in the cabin. The gas removal performance and operational lifetime of the gas trap have been affected by contamination in the ITCS coolant. However, the gas trap has performed flawlessly with regard to its purpose of preventing gas bubbles from causing depriming, overspeed, and shutdown of the ITCS pump. This paper discusses on-orbit events over the course of the last year related to the performance and functioning of the gas trap.

The Space Station provides a unique facility for conducting material processing and life science experiments under microgravity conditions. These conditions place special requirements on the U.S. Laboratory for storing and transporting chemicals and process fluids, reclaiming water from selected experiments, treating and storing experiment wastes, and providing vacuum utilities. To meet these needs and provide a safe laboratory environment, the Process Material Management System (PMMS) is being developed. Preliminary design requirements and concepts related to the PMMS are addressed in addition to discussing the MSFC PMMS breadboard test facility and a preliminary plan for validating the overall system design. The system contains a fluid handling subsystem which manages process fluids required by each experiment while a chemical storage facility safely stores potentially hazardous chemicals.

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.

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 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.

A series of tests has been conducted at the NASA Marshall Space Flight Center (MSFC) to evaluate the performance of a Space Station Freedom (SSF) pre-development water recovery system. Potable, hygiene, and urine reclamation subsystems were integrated with end-use equipment items and successfully operated for a total of 35 days, including 23 days in closed-loop mode with man-in-the-loop. Although several significant subsystem physical anomalies were encountered, reclaimed potable and hygiene water routinely met current SSF water quality specifications. This paper summarizes the test objectives, system design, test activities/protocols, significant results/anomalies, and major lessons learned.

The Water Processor Assembly (WPA) for use on the International Space Station (ISS) includes various technologies for the treatment of waste water. These technologies include filtration, ion exchange, adsorption, catalytic oxidation, and iodination. The WPA hardware implementing portions of these technologies, including the Particulate Filter, Multifiltration Bed, Ion Exchange Bed, and Microbial Check Valve, was recently qualified for chemical performance at the Marshall Space Flight Center. Waste water representing the quality of that produced on the ISS was generated by test subjects and processed by the WPA. Water quality analysis and instrumentation data was acquired throughout the test to monitor hardware performance. This paper documents operation of the test and the assessment of the hardware performance.

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.

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.