Design of the Psyche Spacecraft for NASA's Discovery Program

The NASA Discovery AO in 2014 solicited proposals for space science missions under a cost-cap of $500M for Phases A through D. The earlier Dawn Discovery Mission demonstrated the value of solar electric propulsion (SEP) for enabling planetary science missions that were too expensive and impractical or impossible to conduct using other propulsion methods. The Psyche mission was likewise formulated to use SEP to reach and orbit a Type-M (metal) asteroid in the asteroid belt while remaining under the Discovery cost cap. However, at the time of Psyche’s development, Dawn’s electric propulsion (EP) system, based on the NSTAR gridded-ion thruster, was found to be obsolete and not available for use. For all SEP missions following Dawn, other EP thrusters and power systems that form the heart of the spacecraft needed to be found. Early in mission concept development of the Psyche design, the team prioritized finding an EP system with proven heritage and high Technology Readiness Level. It quickly became apparent that Psyche would benefit from an EP system provided by a commercial satellite manufacturer. The proposal team chose to partner with Space Systems/Loral (now Maxar Space Systems), a company that has built over 40 Earth orbiting spacecraft that have accumulated over 250,000 hours of active EP operation in space. The team developed a spacecraft design that combines Maxar’s experience in high-power electric propulsion systems with JPL’s experience building highly autonomous spacecraft for deep space. The architecture is built around a solar electric propulsion (SEP) chassis, derived from Maxar’s GEO product line, that is coupled with JPL’s deep-space heritage Command & Data Handling (C&DH) systems and flight software to form the Psyche spacecraft bus.