Low-Thrust Propulsion Systems for Small Satellites

Small platforms represent valuable options for small scientific and Earth observation missions. One of the main challenges for microspacecrafts with launch mass below approx. 100 kg is the inclusion of a propulsive subsystem. Such addition would significantly enhance the performance of these platforms, broadening the possible applications and/or extending the operational lifetime. For these applications, electric propulsion systems are more suitable than classical chemical systems as they allow a larger payload mass fraction reducing the propellant mass requirement. The aim of this study is to investigate about state of the art of electric propulsion options for small spacecraft. A selection of possible electric propulsion systems for small satellite based on several requirements (power, thrust, specific impulse) is presented. This paper discusses four typical orbital manoeuvres of fundamental relevance for satellites in low Earth orbit: scenario No. 1 considers a 350 km decrease of orbital altitude; scenario No. 2 is about drag compensation for 90 days at very low altitude. Scenario No. 3 is a combined manoeuvre to change both semi major axis (by 150 km) and inclination (by 0.563 deg) at once. The fourth scenario is about orbit circularization. Results are thus normalized to obtain dimensionless parameters to be compared. Our analysis shows that an electric propulsion system offers significant advantages for small satellites in low Earth orbits in case of altitude variation, moderate inclination change, circularization and drag compensation at very low altitude.