These are habitats that are similar to the types of places that we think life could have originated in and possibility still survive in.

This is a big deal. The south polar region seems to be a geyser field that's bigger than Southern California. . . . We suspect that liquid water also exists on other moons. But none of the water is so close to the surface.

Do you have the right materials and do you the right conditions? The materials are certainly there.

Io is a weird place. We've known that even before Voyager. And each time Galileo has given us a close look, we get more surprises.

Our understanding of the different characteristics of the outer planet moons has undergone a revolution since the Voyager I reconnaissance in 1979. Prior to getting the Voyager data back, most astronomers thought they would find frozen dirt balls with craters on them.