Europa is too far from the sun for sunlight warmth. However, some have postulated that the gravitational pull of the massive planet Jupiter would disrupt the core of Europe enough to generate heat.
Therefore, if you wrap your head around this, we may be looking at a more or less relatively warm ocean, surrounded by a cake of ice. This would happen because the heat is from inside out, instead of outside in. (theoretically)
I don't know. It will be interesting if they get it done. I always wonder about whether or not NASA will wind up introducing some microbe into these galactic destinations. If someone breathed, coughed, or even touched anything that hits that moon, they would introduce DNA and could potentially create, instead of find, a new life form.