Our solar system is host to a wealth of icy worlds that may have water beneath the surface. The Cassini spacecraft recently uncovered evidence of a possible ocean under the surface of Saturn's moon, Mimas.
Mimas is not alone in the possibility of having a global ocean, which would potentially provide a foothold for life to exist. Other worlds under examination include Jupiter's moon, Europa. In 2013, NASA's Hubble Space Telescope observed evidence that Europa erupts water, while the Cassini spacecraft has observed geysers spewing on Saturn's moon, Enceladus.
How likely is habitability on such icy worlds, and how would we search for it? This is one of the questions driving a research team led by Isik Kanik at NASA's Jet Propulsion Laboratory in Pasadena, California. Kanik's team was selected for a new grant from the NASA Astrobiology Institute for a five-year project looking at how metabolism could come about by way of chemical differences on icy worlds, and how signatures of these unbalanced states can be detected. This is assuming that metabolism works similarly on these other worlds as it does on Earth.