Initial Checkout of the Psyche Electric Propulsion System

NASA’s Psyche spacecraft launched on October 13, 2023, and soon afterward the mission operations team began spacecraft initial checkout activities. For the electric propulsion system, the feed system and thruster gimbals were first prepared and then the rest of the subsystem completed an initial operations test during thruster bakeout. Thrust for each thruster was measured across the full range of operating powers and was in good agreement with pre-flight expectations. A weeklong test of the spacecraft and mission operations plan during thrusting activities was successful, but a thruster burn-in phenomenon was observed during full power operation that was longer than expected based on previous flight history. Data accumulated during the initial checkout activities shows that this burn-in behavior is different for each thruster and suggests that it is a result of the thruster discharge transitioning between two different plasma modes that can be mitigated by reducing discharge power and by adjusting the thruster magnet current. At the conclusion of the checkout activities, the subsystem had accumulated 357 hours of thrusting operations while consuming 18.5 kg of propellant and was fully ready to begin the cruise phase of the mission