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A regenerable carbon dioxide (CO2) removal system has been certified for use with the Extravehicular Mobility Unit (EMU), or space suit. The new system, nicknamed “Metox” to reflect its use of metal-oxide as the CO2 sor-bent material, was designed and developed by Hamilton Standard Space Systems International (HSSSI), Inc., under contract1 to the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC). As a part of the certification process, one hundred (100) operating cycles were accumulated on the certification canister and sixteen (16) regeneration cycles on the certification regenerator. This paper presents a summary of those tests. The results characterize canister performance for a wide range of temperatures, pressures and metabolic rates. It also presents regenerator performance under nominal and worst case operating conditions.

The generation (and recovery) of water, rather than the reduction of CO2, drives the requirements for the integration of a Sabatier CO2 Reduction Subsystem (SCRS) within an Air Revitalization Subsystem (ARS). It is important, therefore, to understand the system level decisions that impact the water production capability of the Sabatier CO2 Reduction Subsystem. This paper defines each of the operational parameters that affect water production and loss and explores the impact they each have on total water recovery. The particular subsystem parameters examined include hydrogen and carbon dioxide flow rates, feed gas composition, subsystem operating pressure, condensing heat exchanger performance, heat sink temperature, and phase separator performance. Each of these has a minor contribution to the amount of water lost from the system, but combined, their effect is substantial.

The Regenerable Carbon Dioxide Removal System (RCRS) has been flying on Extended Duration Orbiter (EDO) versions of Shuttle since 1992. Life characteristics of an enhanced sorbent were evaluated after five years of service life on two Orbiter vehicles. Performance data is presented showing excellent carbon dioxide removal. Limited data forces a range of life predictions for the useful life of the sorbent.