A Semi-Continuous, Regenerable System for Trace Contaminant Control in Closed Atmospheres 2007-01-3155

Long term space exploration poses considerable challenges in logistics since launch costs, weight, and volume are all limited. In space life support systems contaminants are generated due to the off-gassing of materials of construction and are also a by-product of crew metabolism. While carbon dioxide is a metabolic contaminant, its control is typically accomplished by a dedicated system, whereas the rest of the contaminants are controlled using a trace contaminant control system (TCCS). Currently, NASA employs various TCCS approaches depending on the mission type and duration. In the Extravehicular Mobility Unit (EMU) this is accomplished with activated carbon as well as strict control on materials of construction. The activated carbon is thermally regenerated in some EMU applications and the adsorbed contaminants are purged to the International Space Station (ISS) where they are subsequently removed. The ISS combines phosphoric impregnated charcoal, high temperature catalysis, and lithium carbonate, along with similar control of materials of construction for the control of trace contaminants. However, in the ISS, or any vehicle such as the Shuttle or Crew Exploration Vehicle, there are significant quantities of non-metallics, in addition to other crew activities such as hygiene and experimentation, which can significantly impact the trace contaminant load. This paper presents an approach to contaminant control which combines electrically regenerable carbon structures, periodically desorbing contaminants to space vacuum, with a photocatalytic oxidation system. This approach uses existing, proven technologies, which require minimal logistics offering significant savings over currently employed systems. The regenerable sorbents eliminate the need to carry non-regenerable sorbent beds, while photocatalytic oxidation uses less power than conventional high temperature oxidation processes.