Bunker buster technology
Might work. If launched from orbit after a mapping phase it could be aimed at the thinnest part of the ice and might actually penetrate to the ocean below. Or maybe there could be a kinetic energy impactor first to knock a hole in the ice followed by a penetrating probe either immediately or in a subsequent orbit? I'm way out of my field here so anyone feel free to tell me I don't know what I'm talking about...
ET''s probably right about the scope of this mission but damnit I'm impatient to get a rover onto the surface or even better a hydrobot into that ocean!