A Low Power Approach to Small Satellite Propulsion

Small Satellites are emerging as the preferred platform for a wide variety of earth orbit and even interplanetary missions. These spacecraft are, by their very nature, extremely limited in volume, mass and power. Existing fluid propulsion options are too large, costly and complex for many small satellite applications. In an attempt to address this problem the Applied Physics Laboratory of Johns Hopkins University, as part of an advanced development contract with NASA, has contracted with V ACCO Industries. The objective of this program is to conceive and demonstrate a cold gas propulsion system specifically designed for small satellites. Major design drivers included low cost, minimum power/mass, small envelope and simple architecture. The Cold Gas Propulsion System (CGPS) resulting from this effort is unique in several ways. It utilizes a simple blow down architecture which requires the entire system to operate at full storage tank pressure. The traditional pressure regulator has been eliminated. This required the development of unique thrusters capable of functioning with inlet pressures to 3000 psi. The thrusters utilize a latching valve design that requires a pulse to open and a pulse to close. Between pulses the thruster is magnetically latched in either the Cardin / Mosher 1 open or closed pOSItion as required. This dramatically reduces the power required by the thruster valves while preserving the option for small impulse bits. In order to minimize mass and cost, the system uses only four thrusters. By mounting these thrusters in a double canted orientation to the spacecraft, pitch, yaw and roll control as well as delta V can be accomplished