The random walk of Main Belt asteroids: orbital mobility by non-destructive collisions

Abstract

Non-destructive collisions among Main Belt asteroids have effects on their orbits due to the transmission of linear momentum. The efficiency of this mechanism depends on several parameters which are currently poorly known. The most critical aspects are (i) the inventory and size distribution of small Main Belt asteroids, with sizes well below a few kilometres; (ii) the energy threshold for collisional fragmentation and fragment dispersion and (iii) the efficiency of linear momentum transfer. In spite of these difficulties, a general statistical model of the dynamical effects of non-destructive collisions can be developed, and is presented here. Based on this model, the consequences of different assumptions concerning the asteroid size distribution and collision physics are computed and discussed. Quantitative evaluations of the collisionally induced orbital mobility in different possible scenarios are presented.