In the Solar System, Enceladus ought to be one of the highest priorities for the world's space agencies. Enceladus has a source of energy (tidal heating), organic material, and liquid water. That's a textbook-like list of those properties needed for life. Moreover, nature has provided astrobiologists with the ultimate free lunch: jets that spurt Enceladus's organic material into space.

However life started, once established, it persisted for over 3.5 billion years and evolved from microbial slime to the sophistication of human civilization.