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A regenerable metal oxide carbon dioxide (CO2) removal system was developed to replace the current means of a nonreusable chemical, lithium hydroxide, for removing the metabolic CO2 of an astronaut in a space suit. Testing indicates that a viable low-volume metal oxide concept can be used in the portable life support system for CO2 removal during Space Station extravehicular activity (EVA). A canister of nearly the same volume as that used for the Space Shuttle, containing 0.10 ft3 (2.8 liters) of silver-oxide-based pellets, was tested; test data analysis indicates that 0.18 ft3 (5.1 liters) of the metal oxide will result in an 8-hour EVA capability. The testing suggests that the metal oxide technology offers a low-volume approach for a reusable CO2 removal concept applicable for at least 40 EVA missions. The development and testing of the breadboard regeneration package is also described.

Supply of oxygen (O2) and hydrogen (H2) by electrolyzing water in space will play an important role in meeting the National Aeronautics and Space Administration's (NASA's) needs and goals for future space missions. Both O2 and H2 are envisioned to be used in a variety of processes including crew life support, spacecraft propulsion, extravehicular activity, electrical power generation/storage as well as in scientific experiment and manufacturing processes. Life Systems, Inc., in conjunction with NASA, has been developing an alkaline-based Static Feed Electrolyzer (SFE). During the development of the water electrolysis technology over the past 23 years, an extensive engineering and scientific data base has been assembled.

The use of metal oxide absorbents in a portable life support system (PLSS) for regenerative removal of both CO2 and H2O vapor is the focus of an ongoing NASA program. This program addresses the rigorous extravehicular activity (EVA) requirements for Space Station Freedom and future long-duration missions. The concurrent removal of CO2 and H2O vapor can simplify the PLSS by combining the CO2 removal and humidity control functions in one component. A further benefit is that the reversible gas/solid chemical reaction of the removal processes permits a regenerative component that does not vent to space. Recently a preprototype full-scale metal oxide carbon dioxide and humidity remover (MOCHR) and a regeneration module were delivered to NASA Johnson Space Center (JSC). Prior to delivery, preliminary testing of the MOCHR and regeneration module was conducted at AiResearch.

Future long-duration manned space missions will require efficient methods for maintenance of viable atmosphere in spacecraft crew cabins. Life Systems, working with NASA, has been developing an integrated regenerative Air Revitalization System (ARS) for removal of carbon dioxide and water vapor and replenishment of oxygen and nitrogen for spacecraft atmosphere. A one-person-capacity experimental ARS (ARX-1) has recently been developed and tested. This paper describes the ARS concept, prior development efforts, design and hardware features of the ARX-1, testing completed, the current test program, and a preliminary design for a one-person flight prototype ARS.

The Sabatier reactor is an exothermic, heterogeneous catalytic reactor that has the function of reducing carbon dioxide to methane and water vapor. Sabatier reactor operation is affected by gravity through the effects of buoyant forces. The buoyant forces affect the transfer of heat and can be significant in determining the temperatures of the various portions of the reactor. The temperatures then affect the fundamental processes such as the chemical reaction rate. This paper presents the results of zero “G” computer model simulations of Sabatier reactor operation. Groundbase experiments were made for various manned loadings under normal ambient and gravity (l-G) conditions and were correlated with normal gravity simulations. The zero “G” simulations show the reactor will run significantly hotter in a zero “G” environment if cooling air flow is not increased to compensate for the loss of natural convections.

Regenerative-type subsystems are being tested at JSC to provide atmosphere revitalization functions of oxygen supply and carbon dioxide (CO2) removal for a future Space Station. Oxygen is supplied by an electrolysis subsystem, developed by General Electric, Wilmington, Mass., which uses the product water from either the CO2 reduction subsystem or a water reclamation process. CO2 is removed and concentrated by an electrochemical process, developed by Life Systems, Inc., Cleveland, Ohio. The concentrated CO2 is reduced in a Sabatier process with the hydrogen from the electrolysis process to water and methane. This subsystem is developed by Hamilton Standard, Windsor Locks, Conn. These subsystems are being integrated into an atmosphere revitalization group. This paper describes the integrated test configuration and the initial checkout test. The feasibility and design compatibility of these subsystems integrated into an air revitalization system is discussed.

Breathing oxygen supply for long-duration manned space missions such as the NASA Space Station may be generated by electrolysis of water produced by the reaction of metabolic carbon dioxide and hydrogen in a Sabatier Methanation Reactor (SMR). A Space Station probable restriction on venting of carbonaceous gases to space will require onboard management of SMR product methane. This may be accomplished via methane decomposition to hydrogen and carbon. The hydrogen could be recycled to the SMR and the carbon would be stored onboard. Under contract with the NASA Johnson Space Center (JSC), Hamilton Standard is currently developing a Carbon Formation Reactor (CFR) that decomposes methane to gaseous hydrogen and dense solid carbon via high temperature pyrolysis. In this paper, the fundamentals of methane pyrolysis to carbon are described and the results of CFR development efforts to date are presented.

The Extravehicular Activity (EVA) operations for Space Station (SS) require that a regenerable carbon dioxide (CO2) absorber be developed for the manned Extravehicular Mobility Unit (EMU). A concept which employs a solid amine resin to remove metabolic CCL and water vapor from the breathing air within the space suit is being developed by the Hamilton Standard Division of United Technologies Corporation under Contract NAS 9-17480 with the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC). The solid amine is packed within a water cooled metal foam matrix heat exchanger to remove the exothermic heat of chemical reaction. After completion of the EVA mission, the amine is regenerated on board the Space Station within the heat exchanger using a combination of heat and vacuum. This paper describes the concept design features, operational considerations and test results during simulated laboratory conditions.

The extravehicular activity (EVA) requirements for Space Station Freedom and future long-duration space missions demand advanced technologies for the life support subsystems in the astronaut portable life support system (PLSS). A NASA-funded program is currently underway to develop a full-scale, breadboard, regenerate metal oxide carbon dioxide (CO2) removal system. This technology is a promising concept to replace the lithium hydroxide absorber presently used for removing CO2 in the recycled breathing gas in the PLSS, but cannot be efficiently regenerated to be used for another EVA mission. In the metal oxide carbon dioxide removal system, an “active” metal oxide compound, contained within a solid absorbent material, effectively removes the CO2 by chemically reacting to form a metal carbonate during astronaut EVA. The absorbent is then regenerated thermally, by decomposing the resulting carbonate and thereby releasing CO2, to reform the metal oxide.

Reduction of metabolic carbon dioxide is one of the essential steps in physiochemical air revitalization for long-duration manned space missions. Under contract with NASA Johnson Space Center, Hamilton Standard is developing an Advanced Carbon Reactor Subsystem (ACRS) to produce water and dense solid carbon from carbon dioxide and hydrogen. The ACRS essentially consists of a Sabatier Methanation Reactor (SMR) to reduce carbon dioxide with hydrogen to methane and water, a gas-liquid separator to remove product water from the methane, and a Carbon Formation Reactor (CFR) to pyrolyze methane to carbon and hydrogen. The hydrogen is recycled to the SMR, while the produce carbon is periodically removed from the CFR. The SMR is well-developed, while the CFR is under development. In this paper, the fundamentals of the SMR and CFR processes are presented and results of Breadboard CFR testing are reported.

A five hour regenerate, nonventing Humidity and CO2 Control Subsystem (HCCS) technology demonstration unit is being developed for potential use in an Advanced Extravehicular Mobility Unit (AEMU) for Space Station application. The HCCS incorporates a weak base anion exchange resin packed in a metal foam matrix heat exchanger. This system simultaneously removes CO2 and water vapor with the resulting exothermic heat of reaction rejected to the heat exchanger. The system has no moving parts resulting in a highly reliable, simple configuration. Regeneration may be accomplished via internal heating and vacuum.