Images from NASA's Galileo probe a few years ago, coupled with previous observations, suggest that Europa's ice - covered surface may conceal a global,
liquid ocean tens of kilometers deep.
If the craft were to crash on the surface of a cold moon like Enceladus, the RTGs could easily thaw a path through
tens of kilometers of ice, and plop down into the
liquid water
ocean beneath, though this might take a long time.