Can there be life elsewhere? A proposed mission to Jupiter’s icy moons would explore Europa and Ganymede.

Data from a previous NASA planetary mission, Galileo, have provided scientists evidence of what appears to be a body of liquid water just beneath the icy surface of Jupiter’s moon, Europa. The data suggest that, not only is the volume of this Europan subsurface ocean similar to that of the North American Great Lakes, but also that there is significant exchange between the moon’s icy shell and the ocean beneath.