meteorite

Presolar grains — tiny bits of solid interstellar material formed before the sun was born — are sometimes found in primitive meteorites. But a noble gas analysis from physicists in Arts & Sciences reveals evidence of presolar grains in part of a meteorite where they are not expected to be found.

A strange stone found in the Moroccan desert was the talk of the recent Lunar and Planetary Science Conference. The stone has highly unusual chemistry, suspiciously like that found by the Messenger space probe, which is currently surveying the surface of Mercury. If it was from Mercury, it would be the first meteorite from that body ever found. The prospects was thrilling but doubts crept in. WUSTL’s Randy Korotev, a lunar meteroite expert, explains the arguments for and against Mercurian origin.

Ann Nguyen chose a risky project for her graduate studies at Washington University in St. Louis. A university team had already sifted through 100,000 grains from a meteorite to look for a particular type of stardust — without success. In 2000, Nguyen decided to try again. About 59,000 grains later, her gutsy decision paid off. In the March 5 issue of Science, Nguyen and her advisor, Ernst K. Zinner, Ph.D., research professor of physics and of earth and planetary sciences, both in Arts & Sciences, describe nine specks of silicate stardust — presolar silicate grains — from one of the most primitive meteorites known.