Feasibility of Developing a Refrigerant-Based Propulsion System for Small Spacecraft

This paper documents the feasibility of developing a low pressure, low-budget, two-phase refrigerant propulsion system for small spacecraft. The spacecraft design teams at the University of Missouri-Rolla, University of Texas at Austin, and Washington University in St Louis have collaboratively researched and assessed the feasibility of using a refrigerant propellant to provide a safe and practical type of propulsion system for the small spacecraft community. As an alternative to a typical inert cold-gas system, the teams investigated two-phase refrigerant-based systems motivated by the excellent propellant storage advantages and the ease of use and inherent safety. A primary benefit is its ability to be stored as a saturated liquid with inherently lower pressures as the constant volume system maintains self-equilibrium at saturation pressure. The associated laboratory safety of using a refrigerant propellant and ease of constructing cold-gas hardware make the propulsion system an ideal choice for low-budget satellite developers. The safety and performance analysis conducted on a general system indicates that with appropriate precautions and conservative design, test and analysis a refrigerant-based propulsion system can be safely implemented on small spacecraft and is a viable propulsion option. This feasibility study has been used as a guide to design and develop propulsion systems for each of the universities.