Orbital and temporal distributions of meteorites originating in the asteroid belt
 Authors:

                  Morbidelli, Alessandro; Gladman, Brett
 Affiliation:

                  Observatoire de Nice, B.P. 4229, 06304 Nice Cedex 4, France; address:morby@obs-nice.fr
 Journal:

                  Meteoritics & Planetary Science, vol. 33, no. 5, pp. 999-1016.
 Publication Date:

                  09/1998
 Origin:

                  M&PS
 Bibliographic Code:

                  1998M&PS...33..999M
 

                                            Abstract

The recent discovery of the importance of Sun--grazing phenomena dramatically changed our understanding of the dynamics of
objects emerging from the asteroid belt via resonant phenomena. The typical lifetimes of such objects are now expected to be
smaller than 10 Myr, demanding a reassessment of our general picture of the meteorite delivery process.By analysing direct
numerical integrations of about 2000 test particles beginning in the v6, 3:1, and 5:2 resonance in the main belt, we have
re-examined the orbital and temporal distribution of meteoroids which journey to Earth. Comparing the results with fireball data,
we find that the orbital distribution of Earth-impacting chondrites is consistent with a steady-state injection of meteoroids into
the 3:1 and v6 resonances. Since this is the most complete and unbiased data set concerning Earth-impacting meteoroids, the
agreement leads us to believe that our model is accurate. The simulations predict a PM fall ratio for chondrites (14% lower than
the observed value of (68%, arguing for a moderate bias being present in this statistic. Most interestingly, the typical meteorite
transfer times predicted by our models are factors of several lower than the typical chondrite exposure ages, implying that these
meteorites acquired most of their exposure in the main belt before entering the resonances. We discuss some processes that would
allow such pre-exposure. The case of achondrites and iron meteorites is also briefly discussed.