The NASA Evolutionary Xenon Thruster (NEXT) project at

Glenn Research Center NASA John H. Glenn Research Center at Lewis Field is a NASA center within the cities of Brook Park and Cleveland between Cleveland Hopkins International Airport and the Rocky River Reservation of Cleveland Metroparks, with a subsidiary facilit ...

is a gridded electrostatic ion thruster about three times as powerful as the NSTAR used on

Dawn Dawn is the time that marks the beginning of twilight before sunrise. It is recognized by the appearance of indirect sunlight being scattered in Earth's atmosphere, when the centre of the Sun's disc has reached 18° below the observer's ...

and

Deep Space 1 ''Deep Space 1'' (DS1) was a NASA technology demonstration spacecraft which flew by an asteroid and a comet. It was part of the New Millennium Program, dedicated to testing advanced technologies. Launched on 24 October 1998, the ''Deep Space ...

spacecraft. and was used in

DART Dart or DART may refer to: * Dart, the equipment in the game of darts Arts, entertainment and media * Dart (comics), an Image Comics superhero * Dart, a character from ''G.I. Joe'' * Dart, a ''Thomas & Friends'' railway engine character * Da ...

. NEXT affords larger delivered payloads, smaller launch vehicle size, and other mission enhancements compared to chemical and other electric propulsion technologies for

Discovery Discovery may refer to: * Discovery (observation), observing or finding something unknown * Discovery (fiction), a character's learning something unknown * Discovery (law), a process in courts of law relating to evidence Discovery, The Discove ...

, New Frontiers, Mars Exploration, and

Flagship A flagship is a vessel used by the commanding officer of a group of naval ships, characteristically a flag officer entitled by custom to fly a distinguishing flag. Used more loosely, it is the lead ship in a fleet of vessels, typically the ...

outer-planet exploration missions.

manufactured the test engine's core ionization chamber, and

Aerojet Rocketdyne Aerojet Rocketdyne is an American manufacturer of rocket, hypersonic, and electric propulsive systems for space, defense, civil and commercial applications. Headquartered in Sacramento, California, the company is owned by Aerojet Rocketdyne Hold ...

designed and built the ion acceleration assembly.

Performance

The NEXT engine is a type of

solar electric propulsion Solar electric propulsion (SEP) refers to the combination of solar cells and electric thrusters to propel a spacecraft through outer space. This technology has been exploited in a variety of spacecraft by the European Space Agency (ESA), th ...

in which thruster systems use the electricity generated by the spacecraft's

solar panel A solar cell panel, solar electric panel, photo-voltaic (PV) module, PV panel or solar panel is an assembly of photovoltaic solar cells mounted in a (usually rectangular) frame, and a neatly organised collection of PV panels is called a photo ...

to accelerate the

xenon Xenon is a chemical element with the symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...

propellant to speeds of up to 90,000 mph (145,000 km/h or 40 km/s). NEXT can consume 6.9 kW power to produce 237 mN

thrust Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that ...

, with a

specific impulse Specific impulse (usually abbreviated ) is a measure of how efficiently a reaction mass engine (a rocket using propellant or a jet engine using fuel) creates thrust. For engines whose reaction mass is only the fuel they carry, specific impulse is ...

of 4,170 seconds (compared to 3120 for NSTAR), and has been run for over five years. It can be throttled down to 0.5 kW power, when it has a

of 1320 seconds.

Longevity and total impulse

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.

Status

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. The ''CAESAR'' mission concept to comet

67P/Churyumov–Gerasimenko 67P/Churyumov–Gerasimenko (abbreviated as 67P or 67P/C–G) is a Jupiter-family comet, originally from the Kuiper belt, with a current orbital period of 6.45 years, a rotation period of approximately 12.4 hours and a maximum velocity of . Chu ...

was a finalist for the

New Frontiers program The New Frontiers program is a series of space exploration missions being conducted by NASA with the purpose of furthering the understanding of the Solar System. The program selects medium-class missions which can provide high science returns. ...

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. After that, 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.

Use in space

Launched in November 2021, for the first time in space, the

Double Asteroid Redirection Test Double Asteroid Redirection Test (DART) is a NASA space mission aimed at testing a method of planetary defense against near-Earth objects (NEOs). It was designed to assess how much a spacecraft impact deflects an asteroid through its transfe ...

(DART) spacecraft used the NEXT-C ion thrusterPlanetary Defense: Double Asteroid Redirection Test (DART) Mission
NASA 2017 powered by 22 m² of solar arrays generating ~3.5 kW.

References

{{Spacecraft propulsion Ion engines

Performance

Longevity and total impulse

Status

Use in space

See also

References