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Long-term manned operation of the National Aeronautics and Space Administration's (NASA's) Space Station will require the use of regenerative processes for the revitalization of the Spacecraft atmosphere. Life Systems, Inc. (Life Systems), in conjunction with NASA's effort to mature water electrolysis technology for applications in the Space Station Environmental Control and Life Support System (ECLSS), is developing an alkaline-based Oxygen Generation Assembly (OGA) which utilizes the Static Feed Electrolyzer (SFE) concept. The OGA is required on the Space Station to provide metabolic oxygen (O2) for the crew, compensate for O2 lost overboard due to Space Station leakage, supply O2 for airlock repressurization and provide hydrogen (H2) for the reduction of carbon dioxide (CO2).

Extensive development testing to support the design of the Space Station Freedom (SSF) Carbon Dioxide (CO2) Reduction Assembly (CReA) has been conducted. Both dual and single reactor eight-person capacity systems, supported by experimental test setups, have been used to broaden the design data base. Multiple catalysts were evaluated. Of significant importance was data that showed that operation of the Bosch reaction at elevated pressure 150-205 kPa (7-15 psig) provides significant increases in process efficiency. These improvements significantly reduce the recycle gas rate necessary to achieve a 99%+ CO2 reduction efficiency. Data presented illus-trates the improvements realized and defines the benefits that the new technology offers in terms of savings in power, weight and volume as illustrated by the SSF CReA.

Among several technologies known for reducing carbon dioxide (CO2), the Sabatier and Bosch processes are the two primary options being considered for application in a regenerable Environmental Control and Life Support System (ECLSS) aboard the projected Space Station. Both processes reduce CO2 by catalytic reaction with hydrogen (H2) and enable the recovery of the metabolically consumed oxygen (O2). The Bosch process produces carbon and water while the Sabatier process produces methane and water. While the technologies involved with these processes are different, each must interface with similar subsystems of a regenerable ECLSS. This paper presents a comparison between the two competing technologies and includes the design and sizing of the respective reactors and other subsystem components for the Space Station application.