Large Collisions on Icy and Rocky Bodies with Strength

Abstract:

Here, we investigate the outcome of collisions between icy-rocky planetary embryos with strength. In the inner solar system, impacts between embryos are hypothesized to generate crustal dichotomies on global scales, e.g., the Borealis Basin on Mars. In the Kuiper Belt, such global scale collisions differ from the inner solar system in important ways. First, bodies are less massive and their mutual collision velocities are smaller in amplitude compared to the inner solar system. As a result, the amount of direct shock heating is small and very localized. Strength is an important factor because shear heating is a process that can deposit energy more deeply into the final body. With a small gravitational potential, the post impact shape of the body may exhibit features related to residual strength. The variety of possible post-impact structures depends on the pre-impact thermal state and level of differentiation of the silicate-ice mixture and impact conditions. Here, we focus on collisions scenarios proposed for the origin of the Pluto system using the CTH shock physics code. We report on the magnitude of thermal processing and residual strength for varying assumptions about initial conditions.