Oxygen Generation by Static Feedwater Electrolysis for Space Station Freedom 921151

Under the Space Station Freedom Program, Boeing is responsible for Work Package (WP) 01 which includes the Habitat and U.S. Laboratory modules. That responsibility includes the integration of the system components of the Environmental Control and Life Support System (ECLSS). Included in the ECLSS is the Air Revitalization Subsystem (ARS). The ARS provides for removal and reduction of metabolic carbon dioxide, removal of trace contaminants, continuous monitoring of the cabin atmosphere composition and oxygen generation. This paper will focus on the oxygen generation aspect of the Space Station Freedom (SSF) ARS.

A Static Feed Water Electrolysis System (SFWES) has been selected by Boeing as the oxygen generator for SSF. The SFWES generates oxygen and hydrogen by the electrolysis of water. Onboard SSF, the feedwater to be electrolyzed will be obtained from the potable water processor. Oxygen will be produced at a level to support astronaut metabolic consumption, animal metabolic consumption, experiment ingestion, cabin leakage and airlock loss. The hydrogen byproduct of the oxygen generation will be provided to the Carbon Dioxide Reduction Subassembly wherein the hydrogen will be reacted with concentrated carbon dioxide to form recyclable water and waste methane.

To date, the SFWES has completed the first phase of ECLSS testing known as the Comparative Test and is currently under test in the Predevelopment Operational Systems Test (POST). SSF is being designed for a crew of 4 astronauts with scarring in place to allow growth to the Eight Man Crew Capability (EMCC) configuration. With regard to the POST test, the oxygen generator will be tested to verify the “scarring” interfaces for the EMCC configuration. Both the Comparative Test and the POST oxygen generators are comprised of 24-cell modules with individual cell active areas of 0.023 m² (0.25 ft² ) These oxygen generators have an oxygen generation capacity of 11.12 to 14.72 lb/day. This paper will discuss the technology and operation of the SFWES, results of testing to date, and the viability of the SFWES as the oxygen generator for Space Station Freedom.