Title:

                  Numerous Weak Resonances Drive Asteroids toward Terrestrial Planets Orbits
 Authors:

                  Morbidelli, A.; Nesvorny, D.
 Affiliation:

                  AA(, Nice Cedex 4, France), AB(, Nice Cedex 4, France)
 Journal:

                  Icarus, Volume 139, Issue Icarus, pp. 295-308. (Icarus Homepage)
 Publication Date:

                  06/1999
 Origin:

                  ICAR
 Abstract Copyright:

                  (c) 1999: Academic Press
 Bibliographic Code:

                  1999Icar..139..295M
 

                                            Abstract

A systematic exploration of the chaotic structure of the asteroid belt is presented, first taking into account only the perturbations
provided by the four giant planets and then including also the effects of the inner planets. We find that both the inner belt (a < 2.5
AU) and the outer part of the main belt (a > 2.8 AU) are mostly chaotic. In the outer part of the belt, chaos is due to the presence of
numerous mean-motion resonances with Jupiter and three-body resonances, Jupiter-Saturn-asteroid. In the inner belt, chaos is
generated by mean motion resonances with Mars and three-body resonances, Mars-Jupiter-asteroid. Due to the chaoticity of the
belt, asteroids tend to slowly migrate in eccentricity. This phenomenon of ``chaotic diffusion'' allows many bodies in the inner
belt to become Mars-crossers. The number of asteroids leaking out from the inner belt is large enough to keep the population of
Mars-crossing asteroids in steady state, despite of the short dynamical lifetime of the latter (~25 Myr). We speculate that chaotic
diffusion could have substantially eroded the high-eccentricity part of the asteroid belt, thus providing the impactors responsible
for the Late Heavy Bombardment phase of the early Solar System.