Solar Electric Propulsion Demonstration Mission Baseline Concept Description

A cost-constrained, solar electric propulsion (SEP) technology demonstration mission (TDM) is described. The mission is fully compliant with the key objectives of NASA's BAA and demonstrates a modular and extensible solar electric propulsion system. It launches in early 2018 and flies multiple LEO-GEO transits over the ~year-long operations period. The SEP TDM Space Vehicle is single flight element with no critical events occurring after launch and solar array deployments. It is based on integrated SEP and Bus Modules allowing parallel development and efficient integration. The SEP Module includes three Hall thruster strings (3 + 0) which can be operated singly, in pairs or simultaneously for full power operations of all 3 together. Advanced, light-weight, blanket solar array technology is employed for the SEP TDM instead of regularly used, rigid panel technology. MegaFlex technology (derived from UltraFlex), using two 10 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 demonstrating transfers from LEO to GEO and back to LEO. This set of high ΔV trajectories demonstrates long-term SEP operations and flies the SEP TDM Space Vehicle through the radiation belts, sustained plasma environments, diverse distributed inertia spacecraft control environments and repeated spacecraft occultations. Substantial mission timeline, mass and propellant margins are built into the mission concept enabling flexibility to accommodate possible mission enhancements and account for uncertainties in mission characteristics.