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Proceedings of the National Academy of Sciences of the United States of America 106 (2009) 6904-6909
A unique basaltic micrometeorite expands the inventory of solar system planetary crusts
Matthieu Gounelle1, Marc Chaussidon2, Alessandro Morbidelli3, Jean-Alix Barrat4, Cécile Engrand5, Michael E. Zolensky6, Kevin D. Mckeegan7

Micrometeorites with diameter ≈100–200 μm dominate the flux of extraterrestrial matter on Earth. The vast majority of micrometeorites are chemically, mineralogically, and isotopically related to carbonaceous chondrites, which amount to only 2.5% of meteorite falls. Here, we report the discovery of the first basaltic micrometeorite (MM40). This micrometeorite is unlike any other basalt known in the solar system as revealed by isotopic data, mineral chemistry, and trace element abundances. The discovery of a new basaltic asteroidal surface expands the solar system inventory of planetary crusts and underlines the importance of micrometeorites for sampling the asteroids' surfaces in a way complementary to meteorites, mainly because they do not suffer dynamical biases as meteorites do. The parent asteroid of MM40 has undergone extensive metamorphism, which ended no earlier than 7.9 Myr after solar system formation. Numerical simulations of dust transport dynamics suggest that MM40 might originate from one of the recently discovered basaltic asteroids that are not members of the Vesta family. The ability to retrieve such a wealth of information from this tiny (a few micrograms) sample is auspicious some years before the launch of a Mars sample return mission.
1 :  LMMNHN - Laboratoire de minéralogie du Muséum National d'Histoire Naturelle
2 :  CRPG - Centre de recherches petrographiques et géochimiques
3 :  OCA - Observatoire de la Cote d'Azur
4 :  Domaines Océaniques
5 :  CSNSM - Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse
6 :  SN2 - National Aeronautics and Space Administration Johnson Space Center
7 :  Department of Earth and Space Sciences
Planète et Univers/Astrophysique/Planétologie et astrophysique de la terre

Physique/Astrophysique/Planétologie et astrophysique de la terre

Planète et Univers/Sciences de la Terre/Géochimie

Sciences de l'environnement/Milieux et Changements globaux
asteroids – cosmic dust – differentiation