The whole sample, reported here this week at the Lunar and Planetary Science Conference, weighs just a few trillionths of a gram, but it’s the first time scientists have laid their hands on primordial material unaltered by the violent birth of the solar system.

 

The Stardust spacecraft, launched in 1999, has already accomplished its prime objective: collecting dust particles in the tail of comet Wild 2 and returning them in a reentry capsule ejected as Stardust passed by Earth in 2006. NASA went to all that trouble because comets were supposed to be the repository of the primordial ice and rock—the product of eons of star birth and death—that went into building the solar system. But it turned out that the minerals in the comet dust that Stardust managed to collect weren’t that pristine: They had been heated, melted, and totally transformed somewhere near the nascent sun and then carried outward to be incorporated into comets in the ultradeep freeze far beyond the outermost planets.