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Future manned space missions and space stations require almost completely closed ECLSS-loops. One important problem is the separation and concentration of CO2 from cabin air and the subsequent recovery of oxygen. A complete CO2-processing system has been developed at Dornier consisting of a CO2-separation and concentration unit (Solid Amine Water Desorption system - SAWD), a catalytic CO2-methanation reactor (Sabatier) and a process water electrolyzer for final oxygen and hydrogen recovery [1]. The current work intends to develop an appropriate membrane-based process as an alternative to the SAWD-process, in order to reduce energy consumption, volume and weight and to provide continuous operation. An extended screening of commercially available solution-diffusion membranes has been performed with the result that the polymers cannot meet the requirements for the advantageous replacement of the SAWD-system [2] [3].

An advanced ECLSS for long duration manned space missions - such as planetary flight missions or planetary bases - requires an almost complete closure of all relevant material loops. The current state of ESA development in the oxygen reclamation system does, however, not correspond to this requirement, because of considerable losses of hydrogen due to the production of methane in the Sabatier reactor. Concerning the recovery of hydrogen from methane, experimental and theoretical work on methane pyrolysis has been performed meanwhile. Different pyrolysis reactor concepts have been investigated. This paper will present the results of the experimental and theoretical investigations in addition to a preliminary design of a breadboard model for a methane pyrolysis system to close the hydrogen loop on the basis of a three-persons crewed space vehicle.