Distal Terrains on Asteroid 4 Vesta Resulting from the Rheasilvia Impact
The geologically recent (~1 Gya) Rheasilvia basin on asteroid 4 Vesta is one of the most
spectacular impact structures in the solar system, with a diameter nearly equal in size to that of
Vesta itself. To date, much of the numerical modeling of this impact has concentrated on the
morphology of the Rheasilvia basin. However, the stress wave produced by an impact of this
size is capable of causing deformation at considerable distance from the basin itself. We use
high resolution hydrocodes modeling coupled with a strain analysis routine in order to understand
the modes and magnitudes of deformation expected globally on Vesta following the Rheasilvia
impact. These simulations give insight into several interesting observations by NASA’s Dawn
spacecraft. First, our results suggest that the major system of graben circling Vesta’s equator
opened shortly after the passage of the Rheasilvia related impact shock wave. Secondly, we find
that the deficiency of small craters at Vesta’s north pole is likely a result of antipodal focusing of
Rheasilvia impact related stresses. The details behind both of these findings are dependent on
material parameters of Vesta’s interior, including core strength, mantle porosity, and damage to
the body from previous major impacts. By matching model output to observation, we can perform
a crude sort of seismology and gain insight into both Vesta’s internal rheology as well as its
impact history.