Planetary Science

Cosmic Crystal Kinetics

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Science  05 Dec 2003:
Vol. 302, Issue 5651, pp. 1627-1629
DOI: 10.1126/science.302.5651.1627e

Fragments of extraterrestrial space debris experience different degrees of heating in the atmosphere. Spinel crystals with different compositions and shapes are ubiquitous products found in most space debris. Spinel grains can rapidly crystallize at high temperatures from space debris that melts on its way through the atmosphere.

Toppani and Libourel produced about 300 different spinels in pulse heating experiments with samples of the Orgueil meteorite and compared these synthetic products with over 130 debris particles. Using the Al2O3 content and FeO/Fe2O3 ratio of the spinels and the composition of the atmosphere, they estimated the entry velocity, angle of entry, duration of the fall, and the altitude at which the spinel formed. From this thermal history they can potentially eliminate the atmospheric effects to estimate the pristine extraterrestrial condition of space debris. — LR

Geochim. Cosmochim. Acta 67, 4621 (2003).

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