It seems, right now, that life is bound to liquid state. Besides Kerbin, Laythe and Eve, there is no other body with liquids on the surface (correct me if I am wrong). So, if there is life in other planets, should be in underground oceans. How thick could be the layer of rock/ice to be drilled with a device? I don’t know. However, I think that a planet that could have liquid state medium at least during the day, could feed bacteria from polyhydrocarbon molecules found on the surface. These molecules could come from a lost early-generated atmosphere at the beginning of the solid state of the planet. If it is not possible (I don’t know), they could come from impacts of asteroids and meteors. The polyhydrocarbon (or polyhydrosilicon xD) could serve as a source of C (or Si) and energy (all what bacteria need). Bacteria can also get energy by oxidation or reduction of Fe, S, and many others, elements that could be present in the surface. (Other bacteria could undo the process of the oxidation/reduction made by the others to get energy as well, and thus, establish a recycling cycle). In any case, everything would freeze during the night and the bacteria would start hibernation until the next day. I know we are talking about the vacuum, and we don’t know yet anything that can grow in these conditions. “Let’s imagine†these bacteria are adapted to these conditions. Maybe the daylight could create a micro atmosphere due to the volatilization of some compounds. This could be a little better for hosting life. These are my bases. Then, I think we should not go into detail concerning what is going to happen with the DNA/RNA, proteins, lipids, sugars… cause we will need N, P, S, trace elements,… and we will get lost. I think anything could be possible; after all, arsenic based DNA exists.