In order to take advantage of electric propulsion for a rendezvous with a near-earth small body such as a commet or an asteroid, very long continuous thruster operation of several years is required. For the asteroid sample and return mission named MUSES-C, the institute of space and astronautical science is developing a new-concept ion engine, microwave discharge ion engine, whose cathode-less discharge chamber made the engine being free from the degradation of the electrodes. To demonstrate the new thruster's lifetime, a full-automated test facility was constructed and the endurance test of the ion engine started in February 1997. The facility consists of a large vacuum chamber evacuated by cryogenic pumps and a thruster system; the latter includes a propellant feed system, microwave power generators, power supply units for ion acceleration, and a data acquisition system. All the engine operation system is integrated into a GPIB bus interface and safely controled by computers without any on-site personnel.
