NEXT (ion thruster)

Purpose

NEXT affords larger delivered payloads, smaller launch vehicle size, and other mission enhancements compared to chemical and other electric propulsion technologies for Discovery, New Frontiers, Mars Exploration, and Flagship outer-planet exploration missions.

Design

The NEXT engine is a type of solar electric propulsion in which thruster systems use the electricity generated by the spacecraft's solar panel to accelerate the xenon propellant to speeds of up to 90,000 mph (145,000 km/h or 40 km/s). It can be throttled down to 0.5 kW power, when it has a specific impulse of 1320 seconds.

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. 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.

In November 2010, it was revealed that the prototype had completed a 48,000 hours (5.5 years) test in December 2009. 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.

Development

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. After 2019, it will be a commercial product for purchase by NASA and non-NASA customers. Aerojet Rocketdyne, and their major sub-contractor ZIN Technologies retain the rights to produce the system, known as NEXT-C for future commercialization.

In 2018, the CAESAR mission concept to comet 67P/Churyumov–Gerasimenko was a finalist for the New Frontiers program mission #4, and if selected, it would have been propelled by the NEXT ion engine. However, on 27 June 2019, the other finalist, the Dragonfly mission, was chosen instead.

Later in 2019, NEXT-C was selected for the DART mission and was successfully delivered to APL in the summer of 2020.

Use in space

Launched in November 2021, for the first time in space, the Double Asteroid Redirection Test (DART) spacecraft used the NEXT-C ion thruster powered by 22 m2 of solar arrays generating ~3.5 kW.

References

References

1. George R Schmidt. "The NASA Evolutionary Xenon Thruster (NEXT): the next step for US deep space propulsion".
2. Herman, Daniel A.. (May 3–7, 2010). "57th Joint Army-Navy-NASA-Air Force (JANNAF) Propulsion Meeting". NASA - [[Glenn Research Center]].
3. [http://www.nasa.gov/centers/glenn/news/pressrel/2013/13-021_thruster.html NASA Thruster Achieves World-Record 5+Years of Operation]. NASA. June 24, 2013.
4. Dwayne Brown. "NASA Thruster Achieves World-Record 5+ Years of Operation".
5. Nancy Smith Kilkenny, SGT, Inc.. "NEXT Provides Lasting Propulsion and High Speeds for Deep Space Missions".
6. (March 2016). "Current Status of NASA Evolutionary Xenon Thruster - Commercial (NEXT-C).".
7. (17 January 2018). "CAESAR Project Overview". [[Lunar and Planetary Institute]].
8. Brown, David. (27 June 2019). "NASA Announces New Dragonfly Drone Mission to Explore Titan". [[The New York Times]].
9. (2021). "NASA’s Evolutionary Xenon Thruster–Commercial (NEXT–C)".
10. [https://www.nasa.gov/planetarydefense/dart Planetary Defense: Double Asteroid Redirection Test (DART) Mission] NASA 2017 {{PD-notice
11. (2017). "2017 IEEE Aerospace Conference".
12. (24 November 2021). "NASA, SpaceX Launch DART: First Planetary Defense Test Mission". NASA.
13. (2019). "2019 IEEE Aerospace Conference".