I always thought the young ice on Europe was a consequence of high-pressure outbursts of material (in this case water) through an otherwise inert crust, a mechanism that dominates on Venus. But now it would appear it is a consequence ofplate tectonics, a mechanism that dominates on Earth.
Could this bring up the possibility of two different kinds of life on Europa? I mean, life on the frozen surface, and different life that's adapted to the warmer water in the mantle?
The surface of Europa is an environment very inimical to life. The Europan atmosphere has a significant percentage of free oxygen atoms, which are highly reactive and would bind very quickly with any complex molecules they run across. There is also the highly ionizing radiation from Jupiter, which would ionize the complex molecules themselves, also changing their structure. However, ice is very good protection against these influences, and already a mere 10 meters under the surface any trapped life form will be completely shielded and its fossils would remain as long the ice exists. Actually, these fossils would be preserved in a far better state than fossils on Earth, because they would not be exposed to high temperatures and rock. We could find out everything we need about their chemistry.
And since there is young ice everywhere due to plate tectonics, these fossils will be found everywhere on Europa. You just need a hardened impactor that would hit the surface at a certain speed, stopping itself under 10 meters of ice, and conduct the analysis. This mission is sufficiently simple that even space agencies with meagre budgets should be able to carry it out.
