Early in its history, the red planet had abundant surface water. Could microbes lurk underground?
With rocky cores heated by tugs from Jupiter, these moons are thought to have potentially life-supporting seas beneath their icy crusts.
This icy moon of Saturn also has subsurface deposits of liquid water or slush, a rocky core, and Saturn's gravity for heat. Active ice volcanoes could be circulating nutrients that life forms could use.
Saturn's largest moon has lots of hydro-carbons as raw material for biologically important molecules. It's extremely cold. Could life exist underground?
It's a long shot, with its crushing atmosphere and surface temperatures that would melt lead. But 30 miles up, conditions might be more favorable. Bacteria on Earth endure much worse.