Express delivery of fossil meteorites from the inner asteroid belt to Sweden

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2006.11.021 Byline: David NesvornA1/2 (a), David VokrouhlickA1/2 (a), William F. Bottke (a), Brett Gladman (b), Therese Haggstrom (c) Keywords: Meteorites; Asteroids; Asteroids; dynamics Abstract: Our understanding of planet formation depends in fundamental ways on what we learn by analyzing the composition, mineralogy, and petrology of meteorites. Yet, it is difficult to deduce the compositional and thermal gradients that existed in the solar nebula from the meteoritic record because, in most cases, we do not know where meteorites with different chemical and isotopic signatures originated. Here we developed a model that tracks the orbits of meteoroid-sized objects as they evolve from the [nu].sub.6 secular resonance to Earth-crossing orbits. We apply this model to determining the number of meteorites accreted on the Earth immediately after a collisional disruption of a D[approximately equal to]200-km-diameter inner-main-belt asteroid in the Flora family region. We show that this event could produce fossil chondrite meteorites found in an [approximately equal to]470 Myr old marine limestone quarry in southern Sweden, the L-chondrite meteorites with shock ages [approximately equal to]470 Myr falling on the Earth today, as well as asteroid-sized fragments in the Flora family. To explain the measured short cosmic-ray exposure ages of fossil meteorites our model requires that the meteoroid-sized fragments were launched at speeds >500 mas.sup.-1 and/or the collisional lifetimes of these objects were much shorter immediately after the breakup event than they are today. Author Affiliation: (a) Department of Space Studies, Southwest Research Institute, 1050 Walnut St., Suite 400, Boulder, CO 80302, USA (b) Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC, V6T 1Z1, Canada (c) Department of Earth Sciences, Marine Geology, Goteborg University, P.O. Box 460, SE-405 30 Goteborg, Sweden Article History: Received 26 August 2006; Revised 23 October 2006