A High Stiffness Boom to Increase the Moment-Arm for a Propulsive Attitude Control System on FalconSAT-3

Small satellite missions requiring attitude control can realize significant mass savings by extending the moment arm of a propulsion-based system. Replacing traditional torque rods and reaction wheels with small thrusters on extendable booms can significantly reduce the mass of the ACS. Small satellite buses pose significant integration challenges when incorporating electric micro-thrusters. Generally these satellites have low power capability and small geometries. This impacts attitude determination and control system (ADACS) thruster performance significantly, as it results in low thrust capability (due to power limitations) and small torque moment arms (due to size limitations). To address these technical challenges, the Air Force Research Laboratory is developing a lightweight deployable boom for extending the moment arm of Busek Inc.’s Micro-Propulsion Attitude Control System (MPACS). Specific engineering requirements include increased stiffness, integrated power, and a telemetry wiring harness embedded within the boom’s multi-functional structure. A major design goal is to standardize a modular integration with satellites using the Evolved Expendable Launch Vehicle (EELV) Secondary Payload Adapter (ESPA). Therefore, the boom is designed to stow within the ESPA interface port, a surface region that is generally unused on ESPA satellites. Deployment of the boom is accomplished with a series of elastic-memory composite (EMC) hinges that extend a multi-functional composite structure to a total length of 4 meters. Gravity-gradient stabilization for tip and roll control is abetted by a 6.2-kg tip mass, comprised of the MPACS micro-thrusters and integrated batteries used to power the boom deployment. The boom design effort is currently underway for the United States Air Force Academy’s (USAFA) FalconSAT-3 (FS3) satellite, manifested for launch in 2006 as a secondary payload on the MLV-06 Space Test Program ESPA flight