European Student Moon Orbiter solar electric propulsion subsystem architecture: An all-electric spacecraft

This paper presents the results of the Phase A study for the solar electric propulsion subsystem selected for the ESA European Student Moon Orbiter spacecraft, performed at QinetiQ under ESA funding. To minimise mass, a so-called “all electric” approach is adopted based around the re-use of a flight-spare GOCE T5 gridded ion engine and the introduction of hollow cathode thrusters (HCTs) for attitude control functions. Three different subsystem architectures are considered and analysed with reference to the mass, cost, risk and level of integration between the HCTs and the T5. The favoured system architecture that best meets the various requirements adopts a shared tank and gas flow controller between the HCTs and the T5, with power being supplied from two dedicated power processing units. The possibility of reducing the propellant requirement by using an engine gimbal mechanism is also presented. The study also demonstrates how an increase in the T5 specific impulse to higher values than used on GOCE does not offer substantial system-level mass savings in this particular case.