Development and coupled thruster / electrolyser tests of a water propulsion system

Green propulsion is a key element of future Space propulsion because being environmentally friendly is not just a legal obligation but it can significantly reduce the hazards to people involved in the handling and thus also the overall lifecycle cost. This reduction is due to the easier handling of propellants compared to state-of-the-art toxic propellants based on Hydrazine.When it comes to a replacement of classical, toxic propellants for long term orbital missions current replacement candidates still have handling limitations because these propellants contain chemical energy. Water is the greenest of all possible propellants with no hazard potential because the energy is added in orbit via solar power. The Water Electrolysis Propulsion (WEP) is a system where gaseous oxygen and hydrogen are produced via electrolysis from pure water over a long period with low electric power and burnt with a high thrust and high Specific Impulse (ISP) when needed. Compared to classical Electric Propulsion Systems in this system the energy generation and usage are decoupled.With own R&T support, German (DLR) and European (ESA) funding this technology and the two key tech-nology bricks (Electrolyser, stoichiometric thruster) have been further matured within ArianeGroup. This paper describes the latest development tests of the space grade electrolyser, the stoichiometric thruster and a coupled test series.