DEVELOPMENT OF A SATELLITE PROPULSION SYSTEM BASED ON WATER ELECTROLYSIS

An overview of the development of a propulsion system based on water electrolysis is given. It uses nontoxic and low-pressure water as the main propellant, which is decomposed via electrolysis once the spacecraft is in orbit to generate the combustible gases hydrogen and oxygen. The system combines high performance with low toxicity and therefore no extensive ground handling, due to the nonexistent risk of highly pressurized or combustible substances. The propulsion system is composed of a water container, an electrolysis system which includes gas storage, and a chemical thruster. Special effort is put into the development of the electrolysis system, which must be capable of generating highly pressurized and dry gases for thruster operation in zero-g environments. A redundant flight-like system has been developed, which allows pressurization of the gases up to 50 bars to enable high impulses per thrust event. A 1-N thruster is designed to be operated on the stoichiometric mixture ratio of the gases generated by electrolysis. Due to the expectedly high combustion temperatures of hydrogen and oxygen at stoichiometric mixture ratio, a certain cooling effort is required. Various thruster designs have been investigated and tested. An investigation of the water storage subsystem has been undertaken to show the feasibility of using 3D-printing processes for manufacturing propellant management devices directly into the tank. The development and testing of the propulsion system are conducted at the vacuum facilities of the Institute of Space Systems in Stuttgart in cooperation with ArianeGroup, Lampoldshausen.