It's an exciting time to be an astrobiologist looking for life beyond Earth, with signs of water spouting up all over the solar system. In the latest example, NASA's Cassini spacecraft has delivered clear evidence that, far beneath the icy crust of Saturn's small moon Enceladus, hydrothermal activity may be at work, similar to what we find in some life-friendly environments on Earth.
That makes three leading contenders for bodies in our solar system that possess life-friendly conditions.
Jupiter's moon Europa hides under its icy crust what may be the largest ocean in the solar system, and there has been a renewed interest in mounting a mission to explore it.
And NASA's Curiosity rover continues to quench our thirst for finding signs of liquid water in Mars' distant past. Curiosity is currently prospecting the water-deposited sedimentary layers on Mount Sharp, left behind by ancient surface seas.
It has been a decade since Cassini first captured images of plumes of material erupting from great fissures in the icy crust of Enceladus, material that it later identified as water mixed with smaller amounts of nitrogen, methane, and carbon dioxide. These plumes told us there was liquid water beneath the surface. We thought at the time that the water may be held in some kind of geyser chamber heated and pressurized by tidal energy supplied by Saturn's gravity.