According to Gizmag, NASA's Evolutionary Xenon Thruster (NEXT), the latest ion engine, has clocked a record 43,000 hours of continuous operation at NASA's Glenn Research Center's Electric Propulsion Laboratory.
Ion engines propelling space exploration
NASA, which has been developing ion engines for decades, has used a version called NSTAR for deep space missions. Deep Space 1, which was launched in 1998, used an ion engine to visit both an asteroid and then a comet in a mission that lasted until 2001. Dawn, which uses three of the NSTAR ion engines, recently finished a visit to the asteroid Vesta and is currently voyaging to Ceres, the largest asteroid in the main belt between the orbits of Mars and Jupiter.
Ion engines compared to chemical rockets
Chemical rockets have a great deal more thrust than do ion engines, but burn only for a few minutes. Ion engines, which accelerate charged ions from an inert gas such as xenon, have an advantage for long space voyages, according to NASA, because they can operate much longer than a chemical rocket, for months or, as NEXT proved, even years. A spacecraft powered by an ion engine builds up a great deal of acceleration over time, achieving speeds that are impossible for a spacecraft with a chemical rocket. Typically, ion engines are powered by solar panels or radioisotope thermal generators (RTGs), which use the decay of plutonium to provide energy.
NEXT the latest version of the ion engine
According to the Gizmag piece, the NEXT is twice as powerful as the current NSTAR, but is lighter and of simpler design. The 43,000 hours of continuous thrust is the equivalent of five years of operation. However, only 770 kilograms of the xenon propellant has been consumed.
The sort of missions NEXT could be used for
Thus far, no missions have been manifested by NASA using the NEXT ion engine. However, a 2006 article in the New Scientist suggested that whereas the NSTAR ion thruster was suitable for missions as far as the asteroid belt, NEXT could power future spacecraft to some of the outer planets, Jupiter and Saturn. That suggests that the NEXT may be the engine of choice for future space probes to Europa, a moon of Jupiter covered by an ice pack that is thought to encase a world-girdling ocean. Titan, a moon of Saturn that has lakes and rivers of liquid hydrocarbon, is another possible target for a future space probe propelled by a NEXT ion engine.
Mark R. Whittington is the author of Children of Apollo and The Last Moonwalker. He has written on space subjects for a variety of periodicals, including The Houston Chronicle, The Washington Post, USA Today, the L.A. Times, and The Weekly Standard.
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