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A Japanese spacecraft that visited an asteroid and perhaps even sampled its surface is returning home. The Hayabusa probe, launched by the Japan Aerospace Exploration Agency (JAXA) in 2003, will release a heat-shielded return capsule on June 13 that may contain the first ever samples captured directly from an asteroid.
JAXA reported June 9 that the spacecraft's final course correction had been completed, leaving Hayabusa on its planned trajectory toward Australia. But whether the capsule can survive the searing heat of atmospheric reentry is another question—as are the contents of the sample chamber. Hayabusa has endured several snags in its mission, and it is not clear whether its unprecedented efforts to collect asteroidal samples—from Itokawa, which has an orbit that crosses that of Mars—bore fruit.
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If all goes as planned, Hayabusa could offer important clues about the ancient solar system. NASA's Stardust spacecraft, which returned samples from the comet Wild 2 in 2006, is still providing new findings about the solar system's formation, a process from which asteroids and comets are thought to be leftover scraps. But unlike Stardust, which released its sample capsule and then proceeded toward another encounter, a planned rendezvous with the comet Tempel 1 in 2011, the Hayabusa mothership will burn up in Earth's atmosphere, according to Aviation Week.
Hayabusa did make a number of detailed observations of the 535-meter-wide Itokawa during its visit. (The asteroid was named shortly after Hayabusa's launch in honor of Hideo Itokawa, a Japanese rocketry pioneer who died in 1999.) The spacecraft even managed to land on Itokawa in 2005, although Hayabusa's release of a tiny companion craft, the hopping explorer Minerva, failed to deliver the smaller craft to the asteroid's surface.
If Hayabusa's capsule can survive its return, the next step will be to carefully examine its contents. "JAXA scientists will retrieve the capsule on 14 June, and by the end of the week, they hope to have it back in their laboratory in Sagamihara, just south of Tokyo," Nature News reports. "There they will first take X-ray images to estimate the amount of dust picked up—if any."
Artist's conception of Hayabusa at the asteroid Itokawa: NASA