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May 2003
Planetary science: Meteorites under fire
Each year about 30,000 tons of tiny interplanetary dust particles fall to Earth. The composition of most of these micrometeorites is similar to that of the larger hydrated, porous meteorites that reach the Earth's surface. But these make up only 3% of the recovered meteorite falls, the majority being anhydrous. This size-related imbalance was thought to be due to atmospheric filtering. Now by firing a propellant gun at samples from the (hydrous) Murchison and (anhydrous) Allende meteorites, Tomeoka et al. find evidence that the imbalance is established in space, before contact with the atmosphere. Hydrous material shatters over a much broader pressure range than anhydrous, suggesting that collisions between asteroids produce a preponderance of hydrated material in the interplanetary dust.
Interplanetary dust from the explosive dispersal of
hydrated asteroids by impacts
KAZUSHIGE TOMEOKA,
KOJI KIRIYAMA, KEIKO NAKAMURA, YASUHIRO YAMAHANA & TOSHIMORI SEKINE
Nature
423, 60–62 (2003); doi:10.1038/nature01567
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