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Stardust’s final act helps other NASA missions

stardust.jpgPosted on behalf of Adam Mann

NASA’s Stardust spacecraft, which visited two comets and sent back to Earth the first solid extraterrestrial samples since the moon landings of the 1970’s, came to the end of its mission during the early morning hours of 25 March (GMT). A paragon of usefulness, even the satellite’s final moments were beneficial to engineers, who commanded the probe to burn its jets one final time in order to provide important information for future spacecraft missions.

“It’s a bittersweet moment for a lot of people on the project,” says Tim Larson, Stardust-NEXT’s project manager at the Jet Propulsion Laboratory in Pasadena, California. “But even in its last day we’re getting good data.”

Because of the zero-g conditions of space, Stardust and other probes can’t be outfitted with a tradition fuel gauge. Instead, engineers on Earth have to estimate the amount of fuel left after each rocket motor firing. During its final burn, Stardust expended approximately 350 grams of fuel. This was on the low end of the team’s estimate range, suggesting that the spacecraft’s tank was very nearly empty and that the established methods for calculating fuel supplies are overestimating, says Larson.

Determining exact fuel levels becomes an issue in extended missions, when every last drop may be needed to continue operations, he says. The data from Stardust will be used for probes such as the Mars Reconnaissance Orbiter, currently on a second extended mission, and the Cassini spacecraft, now on its third extented mission since it arrived at Saturn in 2004.


Since its launch in 1999, Stardust has voyaged through nearly seven billion km of interplanetary space, first passing near asteroid 5535 Annefrank in 2002 and photographing its surface. The spacecraft then flew by comet Wild 2 in 2004, collecting particle samples from the comet’s coma and returning them mission scientists via a sealed capsule which separted from the main spacecraft during an Earth flyby in January 2006, The dust grains recovered from the capsule respresent some of the oldest material yet studied in the solar system.

Earlier this year, during an extended mission, the satellite captured close up images of comet Temple 1, a body previously visited and struck with a projectile form the Deep Impact spacecraft. A comparison of the two encounters gave scientists a rare before-and-after look at a comet’s surface showing the steady changes wrought by exposure to the Sun.

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