Micropropulsion for Space — A Survey of MEMS-based Micro Thrusters and their Solid Propellant Technology

In the last two decades, advances in microsystems technology have made micro mechanics mature enough to envisage miniaturization in the space industry. The motivation behind this development is the reductions in mass, satellite costs and launch costs in parallel with an increase in the reliability and flexibility of satellites. A cluster of many small satellites, commanded from a mothership, or totally independent, will, without any doubt, reduce the risk of mission failure and increase mission flexibility. This revolution in the space industry will rely on propulsion system development to ensure the maneuvering and fine positioning of micro and nano satellites (defined as satellites with mass between 20—100 kg and under 20 kg, respectively). This paper is provides a state-of-the-art review of micro thruster technologies for space applications. the intention is to overview the different technical solutions under investigation in the micropropulsion field, to assess their merits and disadvantages and to try to identify the promising ones in relation to future missions needs. First, the principles of propulsion and basic concepts and equations useful in describing and comparing propulsion systems are described. Then, a review micropropulsion needs for space is made and the options and technologies available for propulsion are presented. An outline is given of the technological efforts made in miniaturizing propulsion systems through examples from current research programs and the different micropropulsion technologies are compared. After illustrating the assets of microsystem technology in the micropropulsion field by the detailed presentation of one particular micropropulsion option investigated at LAAS-CNRS, namely solid propellant micro thruster arrays, a short discussion is given of the capability of microsystem technology to serve micropropulsion needs.