Hydrocode simulation of Ganymede and Europa cratering trends - How thick is Europa's crust?

Pristine craters formed in a target with high heat flow were shallower than for the same impact into a target of lesser heat flow, suggesting that the 'starting' crater morphology for viscous relaxation, isostatic readjustments and erosion rate studies is different for craters formed in times of different heat flow. We find that the crater depth-diameter trend of Europa can only be recreated when simulating impact into an upper brittle ice layer of 7 km depth, with a corresponding geothermal gradient of 0.025 K/m. As this ice thickness estimate is below ∼10 km, results from this work suggest that convective overturn of the surface ice may occur, or have occurred, on Europa making the development of indigenous life a possibility.