NEXT-C Flight Ion System Status

Abstract

The 7.4 kW NEXT-C (NASA’s Evolutionary Xenon Thruster – Commercial) gridded ion thruster system provides a combination of performance and spacecraft integration capabilities that make it uniquely suited for deep space robotic missions. With modifications, the NEXT-C system can meet some high total impulse defense and commercial missions as well. The purpose of the NEXT-C flight hardware development program, jointly funded by NASA and Aerojet Rocketdyne, was to establish a commercial supply of the thruster and power processing unit (PPU) for future NASA missions. The program has completed all development and flight production testing and delivered the first shipset of flight hardware to NASA GRC in early 2020 for use on the Applied Physics Laboratory’s DART (Double Asteroid Redirection Test) mission. The NEXT system was developed to a readiness approaching TRL 6 in the mid-2000s, followed by characterization and long duration testing at NASA Glenn Research Center. The original NEXT project effort culminated in a long duration life test of 50,000 hours on a NASA EM thruster using Aerojet Rocketdyne high fidelity optics. The thruster is throttleable across a thrust range of approximately 25 to 235mN. Thruster specific impulse ranges from 1400 to 4200sec, depending on the throttle condition. Each NEXT-C thruster is powered by a PPU with an input power of up to 7.4kW. The PPU converts spacecraft power, over an unregulated input voltage range from 80 to 160 volts, to the conditions required to operate the thruster, and also utilizes spacecraft 28 Volt power to operate the PPU’s communication and control circuitry. On the NEXT-C program, the component designs have matured to include design updates to increase capability, address issues identified during the development program, and incorporate lessons learned. Aerojet Rocketdyne has completed all program phases of the project, including full protoflight and integration testing of the Engineering Model hardware, Critical Design Review, ground test equipment validation, fabrication of flight hardware and protoflight level acceptance testing. Flight hardware testing included both component level testing of the flight PPU and thruster, culminating in an integrated system level hot fire test that demonstrated the flight controls and operating parameters planned to be utilized on the DART mission. The flight hardware testing was successfully completed to the DART mission requirements. This paper will present the flight system capabilities, latest test results, and flight hardware status for the NEXT-C ion engine system.