On a January morning 10 years ago, tiny pieces of a comet landed on Earth inside of a spacecraft. NASA's Stardust return-sample capsule arrived in Utah with its precious cargo on board, and ever since, principal investigator Don Brownlee (University of Washington) has been combing through the samples to see what it collected after seven years in space.
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Even years later, surprises have emerged. In 2014, Brownlee's team announced that probable interstellar particle tracks were found in the aerogel and aluminum foil particle detectors. A newer paper (by another team) submitted to the Lunar and Planetary Science Conference in Houston suggests this interplanetary dust is also made up in part of glass, which is a rare element in meteoroids.
"We're constantly learning new things using better and better techniques," Brownlee told Discovery News. "The more you look at these, how to deal with them, the more you can refine the techniques."
Stardust collected samples from Comet Wild-2 in 2004, about two years before a part of the spacecraft came back to Earth with samples on board. The spacecraft was a pioneer in sample collection, with only one spacecraft (Japan's Hayabusa, in 2010) doing it since on an asteroid. Hayabusa-2 (in flight now) and NASA's OSIRIS-REx (yet to be launched) plan asteroid sample returns in the coming years.
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