I came back today because I read something exciting this morning:
According to Terence Dickinson's 'The Universe and Beyond' page 55, Europa could easily harbour life because for a few hundred million years or so Europa was covered not by ice but by liquid water. Currently the ice is thought to be about 50 feet thick, but at the time of the oceans Jupiter's radiant heat kept the water liquid. As well, Europa has a thin, water molecule atmosphere.
Atmosphere of Europa "The Galileo mission discovered something amazing! Europa has its own atmosphere, although it is very, very thin. This atmosphere is created when fast moving molecules in Jupiter's magnetosphere hit the surface of Europa and knock out a water molecule. These molecules may float around Europa for awhile, but because of Europa's weak gravity, the "atmosphere" rapidly drifts away."
http://en.wikipedia.org/wiki/Europa_(moon) seems to be incorrect in saying Europa has an oxygen atmosphere .. well, water molecules will be H20.
I propose that because of the distinct, dark linear deposits of organic matter on the surface, that the organic material came largely from undersea volcanoes and/or hydro-thermal, reaching the surface through cracks in the ice.
We know that in earth's arctic region life abounds beneath the polar ice. We also know that life abounds near under hydro-thermal vents.
All of the above rather supports my theory that earth began as a globe of water in which minerals formed, creating the mineral core and layers.
So I stick my thumbs into my ears, spread wide my fingers, waggle them, and say, "Nya, Nya, Nya!"