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The control of trace contaminants on the International Space Station (ISS) is carried out by a combination of activated carbon absorption and catalytic oxidation. The carbon bed absorbs most hydrocarbons, chloro and chlorofluorocarbons (CHCs and CFCs) while the catalytic oxidizer removes compounds such as methane, ethylene, ethane, and carbon monoxide that cannot be absorbed by the charcoal bed. Unfortunately, the Space Station catalyst of 0.5% palladium on alumina does not effectively oxidize CHCs and CFCs, and in fact is powerfully poisoned by them (Wright et al. 1996). Thus, even though the charcoal bed has little affinity for CFCs and CHCs, it must be sized to completely remove these compounds in order to protect the crew and prevent poisoning of the catalytic oxidizer. TDA Research Inc. (TDA), under contract to NASA-JSC, has designed, built, and tested an all-catalytic trace contaminant control system (TCCS) to be used in Phase III of the Early Human Testing Program.

Spacecraft thermal control systems are essential to provide the necessary thermal environment for the crew and to ensure that the equipment functions adequately on space missions. The Ultralight Fabric Reflux Tube (UFRT) was developed by the Pacific Northwest National Laboratory as a lightweight radiator concept to be used on planetary surface-type missions (e.g., Moon, Mars). The UFRT consists of a thin-walled tube (acting as the fluid boundary), overwrapped with a low-mass ceramic fabric (acting as the primary pressure boundary). The tubes are placed in an array in the vertical position with the evaporators at the lower end. Heat is added to the evaporators, which vaporizes the working fluid. The vapor travels to the condenser end section and condenses on the inner wall of the thin-walled tube. The resulting latent heat is radiated to the environment. The fluid condensed on the tube wall is then returned to the evaporator by gravity.