Martian Meteorite Launch: High-Speed Ejecta from Small Craters
James N. Head,12
H. Jay Melosh,1
Boris A. Ivanov3
We performed high-resolution computer simulations of
impacts into homogeneous and layered martian terrain analogs to try to account for the ages and characteristics of the martian meteorite collection found on Earth. We found that craters as small as ~3 kilometers can eject ~107 decimeter-sized fragments from
Mars, which is enough to expect those fragments to appear in the
terrestrial collection. This minimum crater diameter is at least four
times smaller than previous estimates and depends on the physical
composition of the target material. Terrain covered by a weak layer
such as an impact-generated regolith requires larger, therefore rarer,
impacts to eject meteorites. Because older terrain is more likely to be
mantled with such material, we estimate that the martian meteorites
will be biased toward younger ages, which is consistent with the
meteorite collection.
1 Department of Planetary Sciences, University
of Arizona, 1629 East University Boulevard, Tucson, AZ 85721, USA.
2 Raytheon Missile Systems, Post Office Box 11337, Building 805, M/S L5, Tucson, AZ 85734-1337, USA.
3 Institute for the Dynamics of Geospheres, Russian
Academy of Sciences, Moscow, Russia 117939.
