Quote from : Astrobiology: A Very Short Introduction Book

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.