Ion engine to open up the solar system
NASA/JPL NEWS RELEASE
Posted: September 10, 2002
To most vehicle owners, the value of their vehicle decreases while the mileage on the engine increases. That wisdom does not hold true for NASA's ion engine, whose odometer continues to spin to the delight of its owners.
This little engine that could has more than made up for its diminutive size, proving that sometimes less is more -- particularly in space. It was the first non-chemical propulsion system to be used as the primary means of propelling a NASA spacecraft.
Meanwhile, back on Earth, a spare of the Deep Space 1 ion engine has been running continuously since October 1998, setting ion engines on a course to become the preferred method of propulsion for future missions to explore our solar system.
Under the hood
Key to the ion technology is its high exhaust velocity. The ion engine can run on a few hundred grams of propellant per day, making it lightweight. Less weight means less cost to launch, yet an ion-propelled spacecraft can go much faster and farther than any other spacecraft.
Visiting a comet
It successfully completed its primary mission to test these technologies, then exceeded expectations by cashing in on its frequent flyer miles and flying by comet Borrelly. It captured the best close-up pictures of a comet and returned the best science data from a comet ever. The spacecraft was retired in December 2001, but back home its spare engine kept on running.
Putting the pedal to the metal
On August 25, 2002, the ongoing life test of the spare ion thruster passed a major milestone by processing 200 kilograms (441 pounds) of xenon propellant. This amount of propellant, in addition to being a nice round number, is also the amount required for the ion propulsion system on the Dawn spacecraft, which will be the first science mission to use ion propulsion.
Dawn is a mission to explore the structure and composition of Ceres and Vesta, two large asteroids that have remained relatively unchanged since their formation at the dawn of our solar system. The mission is expected to launch in 2006.
"This remarkable achievement is a tribute to everyone on the team at JPL who has performed this enormously difficult test for the past four years," said Sengupta. "What we have learned and continue to learn from this test will significantly benefit near-term applications of ion propulsion, as well as enable the design of the next generation of ion engines for future NASA space missions."
The test team expects the engine to reach its end-of-life at full power sometime in November of this year. At that point, the thruster will no longer be operational at full power, but will still work at the lower power end of the throttle range.
The ion engine's impressive track record may not only make it the propulsion system of choice for future missions, such as Dawn and those to return samples back from Mars, but also for many other potential solar electric propulsion missions. Those missions will benefit from the higher total impulse that this test and supporting analyses have made possible.
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