System-Level CubeSat Propulsion Development for Next-Generation Deep-Space Missions

CubeSats have evolved from educational platforms into capable spacecraft for scientific, commercial, and exploration missions. Extending this capability to deep space and demanding Earth-orbit operations requires propulsion beyond current CubeSat state of practice. Deep-space transfers, precision manoeuvring, drag compensation, and long operational lifetimes demand high specific impulse, high total impulse, and efficient use of limited onboard power. This paper presents the system-level development of an advanced CubeSat Propulsion System (CPS) for deep-space-capable 12U missions. The CPS builds on miniaturised electric propulsion technologies developed by Mars Space Ltd, including the RIT-3.5 ion thruster and DN-3.4 dry neutraliser, to deliver a compact, scalable, flight-ready propulsion architecture that brings mission-class performance into a CubeSat form factor.

The MSL CPS integrates a high-efficiency ion thruster with neutralisation, a miniaturised flow-management system, propellant storage, a Power Processing Unit (PPU), and an auxiliary cold-gas subsystem for attitude control and fine manoeuvres. The design targets >75 kNs total impulse and approximately 3200 s specific impulse, with a 0.8–2.2 mN throttle range at <120 W input power. Development follows an ECSS-tailored systems-engineering approach, with defined interfaces across mechanical, electrical, thermal, and functional domains. Modelling and simulation optimise performance across representative mission profiles, while functional testing validates thrust production, efficiency, and integrated behaviour. Early results show stable operation of the RIT-3.5 and DN-3.4 engineering models, supporting the CPS as a baseline solution for long-duration missions. The modular architecture also supports adaptation for LEO missions requiring continuous drag compensation.

Ongoing work focuses on subsystem coupling tests, AIT strategy maturation, and full-system performance demonstration, guided by requirements and integration planning from the HENON mission programme. With continued integration and qualification, the CPS can significantly broaden CubeSat mission envelopes from advanced Earth-orbit operations to deep-space missions.