By Ron Cowen
The first study of comet dust brought to Earth by a spacecraft has revealed several minerals that could have formed only at the fiery temperatures close to the sun or another star. The findings come as a surprise because comets, frozen relics of the early solar system, were born beyond the orbit of Neptune and spend most of their time there.
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Don Brownlee of the University of Washington in Seattle and his colleagues base their findings on the first particles they’ve examined from the Stardust craft, which sped within 236 kilometers of the nucleus of Comet Wild 2 in 2004 and collected material expelled by the frozen body. In January, a canister of the samples parachuted to a Utah desert (SN: 1/21/06, p. 37: Available to subscribers at Pay Dirt: Cometary dust collector comes home).