Cosmic dirt may strut asteroidal stuff.

Cosmic dirt may strut asteroidal stuff

A microscopic interplanetary dust particle (IDP) snagged by a NASA research plane may help scientists determine the mineral makeup of the solar system's asteroid population, according to a report in the Feb. 1 SCIENCE.

Astronomers think most meteorites originate in the solar system's asteroid belt, with a mineral content reflecting that of their asteroidal parents. But meteorites that visit Earth may represent only a small segment of the asteroid belt, say Donald E. Brownlee of the University of Washington in Seattle and John P. Bradley of McCrone Associates, Inc., in Westmont, III.

IDPs show a variety of mineralogically distinct compositions, but until now, astronomers had never directly linked an IDP to a meteoritic source. Brownlee and Bradley report that one IDP from the NASA sampling contains tochnilinite, a mineral that appears only in a specific class of meteorites, suggesting a common asteroidal source for the IDP and these meteorites. This link suggests that the different mineralogy of other IDPs might reflect the composition of asteroids that have never sent meteorites to Earth. Unfortunately, proving the theory would require actual samples of these asteroids or their meteoritic messengers, and Brownlee says he isn't holding his breath for that.