Since NASA's Stardust mission returned in 2006 from its trip of billions of miles collecting the dust of a comet called Wild2 and dropped it samples down to Earth in the Utah desert, the samples have raised all sorts of questions about how comets formed and what the early solar system was like. In a study this week in Science, there's a new surprise. Scientists say that the comet sample contains chemicals that must have formed in our home turf, the inner solar system. Lead researcher Jennifer Matzel studies a tiny particle taken from Stardust's sample, a piece just five micrometers across. In it her team found the mark of materials that would have formed under high temperatures.
Matzel, who specializes in using the decay rates of radioactive chemical elements to assess ancient dates, determined that the Stardust particle must have crystallized just 1.7 million years after the oldest solid ...
