A Review of High Thrust, High Delta-V Options for Microsatellite Missions

Microsatellites have been suggested as a means of enhancing a variety of proposed space missions, ranging from low Earth orbit to Solar System exploration. With improvements in propulsion technology geared toward microsatellites, the ultimate delta-V (∆V) capabilities of some microsatellite systems are now in the range of several km/s, opening the doors to a variety of high ∆V, fast response scenarios. This paper provides a brief overview of propulsion technologies currently available for microsatellites, and an evaluation of each technology for potential use in a demanding mission. The sample mission is that of a microsatellite inspector which, starting in a 200 km parking orbit, must be diverted to rendezvous with another satellite in orbit at a different altitude and inclination. It is found that existing bipropellant microrocket designs provide a high thrust value, combined with a 300 s specific impulse, allowing for response times of only a few hours for such an inspector mission with ∆V requirements over 1 km/s. Miniaturized electrostatic thrusters provide the largest ultimate ∆V capability, approaching 10 km/s, but with a very low thrust level and therefore a response time capability of several months. Newly developed micro-solar thermal systems fill in the middle ground of these two options, providing the moderate thrust levels and specific impulse values necessary for a response time on the order of one day and a ∆V of several km/s. I