Versatile Attitude Control Actuators for Sub-Milliarcsecond Precision Pointing

In cooperation with ROCCOR LLC, Busek seeks to develop thruster heads integrated with deployable booms. The high resolution, low quiescence and extreme throttling capabilities of Busek electrospray propulsion, combined with the customizable moment arms afforded by ROCCORs compact deployables will ensure the system is applicable to a wide variety of mission concepts. A preliminary performance map was obtained for the BET-1mN thruster, demonstrating hundreds’ of µN’s of thrust from a single emitter. Time of flight measurements indicated mixed mode operation (droplets/ions), indicating that updated thrust control algorithms may be necessary, as present implementations focus on droplet or ion dominated emission. Thrust modulations were demonstrated via control of flow rate and beam voltage, demonstrating deep throttling and operation over a wide range of conditions. Size, Weight, and Power (SWaP) for two integrated BET-1mN thruster systems were provided to the ROCCOR LLC and used to develop requirements for the boom. A notional 2m deployable boom design was developed and static load modeling performed to identify deflection. Under the Phase II effort, Busek shall update test setups to include in-situ mass flow measurement during direct thrust measurement in order to fully assess thruster performance. Additional thruster characterization shall focus on completing parameterized thruster performance while also measuring thrust noise, stability, and capturing electrospray plume sweeps. Updated thrust control algorithms will be implemented in hardware/firmware and commanded thrust control demonstrated as part of an integrated test with the BET-1mN thruster. Deployable boom requirements will be updated and a prototype boom fabricated and tested. Static load testing will be performed to validate Phase I modeling results.