Chemical and cold gas propulsion systems

This chapter discusses the current status of chemical and cold gas micro-propulsion systems for small satellites, with a particular focus on CubeSats. Initially, a short historical background is presented, focusing specifically on the precursor cold gas systems developed and demonstrated on small spacecraft in the decade 2000-10. A brief overview of the principle of operation of systems based on the thermodynamic expansion of a gas in a nozzle is then provided, including the simplified equations for characterizing their performance based on the one-dimensional, isentropic Ideal Rocket Theory. In particular, the specific technical challenges associated with the miniaturization of this class of propulsion systems are highlighted and shortly explained. The current state-of-the-art available commercial-off-the-shelf chemical and cold gas micro-propulsion systems is then described in detail, including comparative tables with their main design characteristics and performance parameters. Based on these tables, performance charts are presented that define a range of possible applications of this class of micro-propulsion systems to small satellite missions and tasks. Finally, some of the future expectations in the development of these systems are briefly discussed.