NSTAR flight thruster qualification testing

Abstract

Deep Space 1 is a technology demonstration mission scheduled to be launched in October 1998. One of those technologies is the NSTAR 30 cm diameter xenon ion thruster which will provide the primary propulsion. Three Flight-design thrusters were designed and built by Hughes Electron Dynamics Division, with assistance from NASA's Lewis Research Center. The first thruster was a Pathfinder to finalize the fabrication and assembly procedures for the other thrusters. Two flight-worthy thrusters were then fabricated and tested to Protoflight Qualification levels at NASA's Lewis Research Center and Jet Propulsion Laboratory. Each thruster was performance tested before and after Vibration Tests, integrated with different flight power processors and digital control interface units, and underwent Thermal Vacuum Tests with engine starts from -97 °C. Performance tests included neutralizer, discharge chamber, and ion optics characterizations as well as measurements of thruster efficiency over the full 0.5 to 2.3 kW power throttle range. The performance, at both component and thruster levels, was as expected and found to be quite repeatable with negligible dispersion between thrusters. After final functional tests, one thruster was installed on the DS 1 spacecraft while the other was set aside as a flight spare.