Engineers at the European Space Agency have developed a highly efficient, miniature thruster, the Iridium Catalysed Electrolysis CubeSat Thruster (ICE-Cube Thruster), measuring just 1 mm in length. This compact design is intended for CubeSats, enabling maneuverability without the need for large gas propellant storage. The thruster operates by electrolyzing water into hydrogen and oxygen, expelling them into space to generate thrust. In tests, it achieved 1.25 millinewtons of sustained thrust, suitable for CubeSat missions. The thruster’s simplicity and lack of pressurization requirements make it well-suited for the growing small satellite market, utilizing solar arrays for power. Currently, it has undergone laboratory testing and shows promise for CubeSat propulsion.
Source: https://www.universetoday.com/163280/spacecraft-could-be-equipped-with-tiny-thrusters-that-use-water-for-propellant/