Landers
I've been looking at articles in AvWeek on penetrating bombs. I'm wondering if it isn't possible to construct a short-term probe that could actually punch into Europa at high velocity and survive.
While there's no way you could make something that would survive Jupiter-system approach velocity, you might make something that could survive Europa-orbit velocity, or some large fraction of it. The tougher the penetrator, the less delta-vee you have to use up to land it.
Others issues include getting a signal out of a buried probe. Long wave?