Hydrocode simulations of micrometeorite impacts on the heat shield of the Mars Sample Return Earth entry vehicle

Micrometeorite impacts pose a significant risk to the Mars Sample Return mission. Of particular concern was potential damage to the heat shield of the Earth Entry Vehicle on its trip to Mars and back, and the consequences if the vehicle attempted entry into Earth’s atmosphere with a damaged heat shield, which could lead to overheating and failure of the primary structure. Due to planetary protection requirements for robust containment of the samples currently being collected on Mars, the tolerable risk is orders of magnitude lower than any previous mission. To meet these requirements without an excessively large and heavy heat shield, hydrocode simulations were used to make more accurate predictions of the damage from meteorite impacts. This paper covers the development and experimental validation of hydrocode simulations of impacts into several potential materials, and various potential heat shield designs. It then extends the simulations beyond the ground testable limit of ∼7 km/s to address impacts at speeds up to 70 km/s, for the full range of meteorite densities from porous ice through rock to iron.