re: A Submarine for Europa
Dang, as usual, I can't get at the original paper without coughing up 30 bucks). I'd like to see how the communication issue was handled.
While I really like the idea of something exploring the deep Europan seas, as McKinnon points out in the article, you could find out a great deal about what's under the ice with a much simpler lander plopped down near some place where deep ocean water has been spewed out onto the surface and frozen.
A drilling system to dig down and analyze ice that has not been exposed to as much radiation would be a lot easier to build.