We use three different models of asteroid 433 Eros (D.L. Mitchell et al., submitted to Icarus, 1996) to study the relation between asteroid shape and patterns of ejecta redistribution. Each model is based on Goldstone radar spectra from Eros' 1975 close approach (Jurgens and Goldstein 1976, Icarus 28, 1-15). The models are a triaxial ellipsoid and two non-axisymmetric shapes, all constrained to be in principal-axis rotation. Both non-axisymmetric shapes exhibit one or more large concavities on one side of the asteroid while the opposing side is highly convex. The simulated impacts map two-dimensional impact ejecta fields computed for consolidated and unconsolidated basalt onto the three-dimensional asteroid model. The initial ejecta field is symmetric about the impact axis and the impacts occur normal to the surface. Each particle in the ejecta field is assigned a volume so the mass flow of the ejecta field over the asteroid can be tracked. These impacts are applied at different points on the asteroid surface, detailed dynamical trajectories for each particle are computed, and original and final positions are recorded. The dynamical simulations include a coefficient of restitution that allow the particles to re-impact the surface multiple times. As predicted by theory (Scheeres, et al. 1996, Icarus 121, 67-87), the ejecta fields tend to migrate towards the leading edges of the asteroid. Inclusion of multiple particle impacts cause the ejecta fields to be more widely distributed and lead to a migration of the ejecta from the equator. Should these general trends persist under different conditions and assumptions, the cumulative effect of non-catastrophic impacts would be to re-distribute asteroid mass from the equator and trailing edges of the body to the poles and leading edges. Local topography can influence the final ejecta distribution and, in specific regions, can mask general trends. For example, the larger concavities can trap ejecta fields and re-distribute them within their general boundaries. These results may have broad implications for our understanding of the evolution of asteroid shapes and spin states.
AAS/Division for Planetary Sciences Meeting Abstracts #28
- Pub Date:
- September 1996