Propulsion and attitude control for Foresail-2: harnessing water electrolysis propulsion in a 6U CubeSat mission

Abstract The Foresail-2 mission, a 6U CubeSat developed by the Finnish Center of Excellence in Research of Sustainable Space, seeks to investigate ultra-low-frequency waves in the inner magnetosphere and validate innovative de-orbiting technologies. The mission’s demanding attitude control requirements, including sun-pointing spin axis stabilization and tether-assisted de-orbiting, pose significant challenges, particularly in Geostationary Transfer Orbit where conventional propulsion systems are ineffective. This paper introduces the Water Electrolysis Propulsion (WEP) system as a novel, green propulsion solution tailored to the mission’s needs. By electrolysing onboard water to produce hydrogen and oxygen propellants, WEP offers high specific impulse, compact storage and reduced power demands, while aligning with emerging sustainability standards. Through detailed analysis of system architecture, integration and performance, this paper demonstrates WEP’s potential to enable precise attitude control and de-orbiting for CubeSats, paving the way for scalable propulsion in future small satellite missions.