Benchmarking iSALE and CTH shock physics codes to in situ high-velocity
impact experiments into Fe-Ni targets
Abstract
Cratering is a prominent evolutionary process on asteroids. Crater
morphologies, regolith generation, bulk fracturing and projectile
implantation are all examples of asteroidal surface evolution resulting
from impact processes. With the upcoming launch of the Psyche
mission in 2022, followed by the spacecraft’s arrival at the 225-km
presumed metal-rich asteroid, characterizing impact processes on
relevant metal bodies is key for interpreting mission data. Small-scale
impact experiments into metals (e.g., iron, aluminum, copper, steel)
have shown that crater morphologies into these materials are different
than rocky targets — exhibiting notable distinctive features such as
raised, sharp rims, and deeper cavities. While several impact codes have
been used to simulate and benchmark laboratory scale impacts on rocky
targets, it has not yet been shown how well these codes match observed
crater shapes in Fe-Ni materials which may constitute the metallic
component of Psyche. Here we have used iSALE and CTH shock physics codes
to simulate and compare with the observed experimental crater
morphologies in Fe-Ni targets. It was found that, when using material
strength parameters directly measured in laboratory mechanical tests, at
low and high strain-rates and relevant temperatures, it is possible to
closely match crater diameters and depths from the impact tests.