TheNASA Evolutionary Xenon Thruster (NEXT) project atGlenn Research Center is agridded electrostatic ion thruster about three times as powerful as theNSTAR used onDawn andDeep Space 1 spacecraft.[1][2] It was used inDART, launched in 2021.
Glenn Research Center manufactured the test engine's core ionization chamber, andAerojet Rocketdyne designed and built the ion acceleration assembly.[3][4]
NEXT affords larger delivered payloads, smaller launch vehicle size, and other mission enhancements compared to chemical and other electric propulsion technologies forDiscovery,New Frontiers,Mars Exploration, andFlagship outer-planet exploration missions.[2]
The NEXT engine is a type ofsolar electric propulsion in which thruster systems use the electricity generated by the spacecraft'ssolar panel to accelerate thexenon propellant to speeds of up to 90,000 mph (145,000 km/h or 40 km/s).[3] NEXT can consume 6.9 kW power to produce 237 mNthrust, with aspecific impulse of 4,170 seconds (compared to 3120 forNSTAR),[2] and has been run for over five years.[5] It can be throttled down to 0.5 kW power, when it has aspecific impulse of 1320 seconds.[2]
The NEXT thruster has demonstrated, in ground tests, a total impulse of 17 MN·s; which as of 2010 was the highest total impulse ever demonstrated by an ion thruster.[2] A beam extraction area 1.6 times that of NSTAR allows higher thruster input power while maintaining low voltages and ion current densities, thus maintaining thruster longevity.[2]
In November 2010, it was revealed that the prototype had completed a 48,000 hours (5.5 years) test in December 2009.[3][5][6] Thruster performance characteristics, measured over the entire throttle range of the thruster, were within predictions and the engine showed little signs of degradation and is ready for mission opportunities.[2]
NEXT completed its System Requirement Review in July 2015 and Preliminary Design Review in February 2016. The first two flight units will be available in early 2019.[7] After 2019, it will be a commercial product for purchase by NASA and non-NASA customers.[7] Aerojet Rocketdyne, and their major sub-contractor ZIN Technologies retain the rights to produce the system, known asNEXT-C for future commercialization.[7]
In 2018, theCAESAR mission concept to comet67P/Churyumov–Gerasimenko was a finalist for theNew Frontiers program mission #4, and if selected, it would have been propelled by the NEXT ion engine.[8] However, on 27 June 2019, the other finalist, theDragonfly mission, was chosen instead.[9]
NEXT-C was selected[when?] for the DART mission.
Launched in November 2021, for the first time in space, theDouble Asteroid Redirection Test (DART) spacecraft used the NEXT-C ion thruster[10][11][12] powered by 22 m2 of solar arrays generating ~3.5 kW.[13]
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