New concepts for the avoidance or utilisation of methane in life support systems

Due to high resupply costs, especially for long-duration stays in space habitats beyond low earth orbit, future manned space missions will require life support systems (LSS) with a high degree of regenerativity. Possible ways to overcome the waste of resources and to save on resupply mass are therefore of major interest for the development of next generation environmental control and life support systems.The advanced closed-loop system (ACLS) for air revitalization, which is currently being developed by the European Space Agency, will be able to recover the oxygen from exhaled carbon dioxide by use of a Sabatier reactor (see Fig. 1). However, the employed process generates methane as a side product. Current plans envisage it to be vented over board, but the resulting loss would necessitate the resupply of hydrogen.In order to prevent this waste of methane, there are three options: The LSS could be altered to not produce any methane at all, the methane could be cracked into its constituents and reused, or methane itself could be put to use as a resource.Different approaches were examined, and ideas for a Bosch–Boudouard reactor (no methane production) as well as the design study of a pyrolysis thruster (methane cracking and partial use for propulsion) are presented in this paper.