In-flight performance of the NSTAR ion propulsion system on the Deep Space One mission

Deep Space 1 is the first interplanetary spacecraft to use an ion propulsion system for the primary delta-v maneuvers. The purpose of the mission is to validate a number of technologies, including ion propulsion and a high degree of spacecraft autonomy, on a flyby of an asteroid and two comets. The ion propulsion system has operated for a total of 3500 hours at engine power levels ranging from 0.48 to 1.94 kW and has completed the encounter with the asteroid 1992KD and the first set of deterministic burns required for a 2001 encounter with comet Wilson-Harrington. The system has worked extremely well after an initial grid short was cleared after launch. Operation during this primary mission phase has demonstrated all ion propulsion system and autonomous navigation functions. All propulsion system operating parameters are very close to the expected values with the exception of the thrust at higher power levels, which is about 2 percent lower than that calculated from the electrical parameters. This paper provides an overview of the system and presents the first flight validation data on an ion propulsion system in interplanetary space.