Modelling the Disruption and Reaccumulation of Miranda
V. Vanzani, F. Marzari (Univ. Padova), D. R. Davis, S. J. Weidenschilling (PSI), E. Dotto (Univ. Padova)
The heavily cratered surfaces of the largest Uranian satellites and the unusual surface geology of Miranda suggest that these bodies could have been catastrophically disrupted by collision and then reaccumulated over solar system history (Smith et al., 1986; Mckinnon et al., 1991).
Using the model described by Marzari et al. (1995, Icarus 113, 168) we have simulated the breakup of Miranda by a high velocity impact. With this model we have produced realistic initial conditions for the numerical algorithm of Spaute et al. (1992, Icarus 92, 147) which has been used to model the subsequent reaccumulation of the satellite from the ring of fragments. All the possible outcomes of two body collisions are considered in the model of Spaute et al. (1992): accretion, inelastic rebound, cratering and fragmentation.
Our numerical simulations show that the reaccumulation of Miranda occurs on
a short timescale ( 
years) in spite of the initial large
dispersion of the ring debris and the presence of Ariel at the outer border
of the ring. The reaccumulation is characterized by two stages. An initial
stage during which shattering and cratering dominate and all bodies smaller
than 20 km are destroyed. In the second stage the large survived fragments
grow by accumulating the small comminuted fragments and finally, colliding
each other, rebuild a new Miranda.