Icy Life

Noting that the most likely places to find life elsewhere in the Solar System are cold-- Mars, Jupiter's moon Europa, Saturn's Encyladus-- scientists are looking at life associated with ice sheets on Earth in an attempt to understand how they might detect life on those other worlds.  Methane might be the key. Methane can be created by both geological and biological processes, but it exists in different isotopic versions. If a methane isotope can be firmly tied to biology, that would be a useful marker.

Using Earth analogies probably has its limits, however.  It's reasonable to assume that the life around Earth's ice sheets, for example, originated elsewhere, spread to the cold regions, and adapted.  That history might make the life on Earth's ice sheets quite different from life that had to arise and endure in bitter cold.