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For long duration manned space missions an advanced ECLSS is required to recycle all consumables to a maximum extend possible. Recycling of oxygen out of the atmosphere in a crewed spacecraft is more important the longer the duration of the mission (ISS, Moon, Mars). On behalf of ESA, an air revitalization technology, to reclaim the oxygen from metabolically produced carbon dioxide, was developed in a step-wise approach since 1985. Herein, the air revitalization system technology demonstrator ( ARSD ), designed for a crew of 3 man, was built and successfully tested in a closed chamber for about 600 hours. (/1/) The current concept of the ARSD leads still to a considerable loss of hydrogen, due to the production of methane, which is currently vented. In order to close the hydrogen loop in the air revitalization system, a study was performed to demonstrate the feasibility to decompose methane, reclaim the hydrogen and dispose the deposited carbon.

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.

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].

Europe is now implementing the COLUMBUS APM programme. The more ambitious planning of an European Free Flyer and Lunar mission are under orientation. Timewise, this gives some relief from the challenges for the Environmental Control and Life Support System (ECLSS). However, some of these challenging new technologies have already been subject of development programmes in the past, others which will be reported in this paper are currently under investigation. To regain the oxygen from the metabolic process a physicochemical system is under development. The selected chain is the CO2 concentration with a solid amine resin, the CO2 reduction via Sabatier reaction and the oxygen recovery by water electrolysis with fixed alkine electrolysis. To prove the concept a test bench has been built, starting in a first step with the set up of a CO2 Processing S/S (CO2 concentrator, CO2 management, CO2 reduction assembly).