Impact comminution of icy targets in the outer solar system: Application of hydrocodes Original Research Article

The availability of hydrocodes with crack growth modelling provides an opportunity to study the extended spallation region for brittle targets such as ices, where conchoidal fracture dominates the volume of crater excavation. Autodyn version 4.1.0.9 using Johnson-Holmquist crack modelling is explored in this role to investigate ejecta size and velocity distributions following validation in quasi-static runs which mimic laboratory measurements of glass and water ice. It is found that the code can model, with realistic values, bulk material properties and fracture patterns. Ejecta size and velocity distributions are presented which indicate low ejecta velocities which would lead to regolith development on 500m diameter objects in the Jovian or Saturnian system. The code is also able to track momentum reaction during impact and establish catastrophic collision limits of icy or rocky bodies under meteoroid impacts.