CubeSat Propulsion Using Electrospray Thrusters

The space industry is showing increasing interest in small, low-cost CubeSats which can serve a variety of missions. Busek Co, Inc is developing a small TOAC (thruster-on-a-card) that is designed to provide both primary and ACS propulsion within a 1U CubeSat volume. Electrospray thrusters operate by electrostatically accelerating charged droplets of an electrically conductive ionic liquid, and are capable of providing a high degree of throttling and variable Isp. The electrospray thruster, propellant reservoir and power processing unit and digital control interface unit (DCIU) occupy less than 1U and will provide over 350m/s delta-v for a 1kg CubeSat. The propulsion system presented here has a target thrust of 75μN, is designed to operate on a specific impulse of 800-1600s and a nominal power consumption of 2.5W. This propulsion system can be used to enable formation flying, pointing and orbit maintenance applications for CubeSats. This device has grown from AFRL and NASA development heritage, including Busek’s recent delivery of 8 flight electrospray thrusters to Space Technology 7 Disturbance Reduction System (ST7-DRS) technology demonstration mission, sponsored by NASA’s New Millennium Program and managed by JPL, slated to fly in 2011. This paper describes the electrospray thruster system and its capability.