William D. Deininger

Solar Electric Propulsion Demonstration Mission Using a Minotaur IV Launch Vehicle

The Solar Electric Propulsion (SEP) Technology Demonstration Mission (TDM) is a stepping stone leading to a reusable electric propulsion stage by demonstrating high power (10s kW) transfers from LEO to GEO and back to LEO. A scaled SEP TDM concept is described which can be launched on a Minotaur IV launch vehicle (LV). The mission concept is formulated in response to NASA’s BAA, meets all BAA requirements and demonstrates a modular and extensible solar electric propulsion system. It launches in early 2018 and flies multiple LEO-GEO transits over the 1-2 year-long operations period. The SEP TDM Space Vehicle (SV) is based on integrated SEP and Bus Modules allowing parallel development and efficient integration. The SEP Module includes two 5 kW Hall thruster strings (2 + 0) which can be operated singly or as a pair, or two NEXT strings which can be operated singly or as a pair. Advanced, light-weight, blanket solar array technology is employed for the SEP TDM instead of typically used, rigid panel technology. MegaFlex technology, using two 9 m-diameter wings, is baselined. The power and propulsion systems are at sufficient specific power to demonstrate the movement of large payloads from LEO to higher energy orbits at performance values consistent with future higher power electric propulsion capabilities (Isp, thrust-to-power, power-to-mass). The SEP TDM, and its SEP Module concept, represents a key infusion point to a reusable electric propulsion stage by executing a set of high ΔV trajectories to demonstrate long-term SEP operations, and fly the SEP TDM Space Vehicle through the radiation belts, sustained plasma environments, diverse distributed inertia spacecraft control environments and repeated spacecraft occultations.