Cassini at Saturn's moon Enceladus.

On Oct. 28, 2015, NASA's Cassini spacecraft will take the deepest dive ever through the plume of Saturn's moon Enceladus. Scientists hope this close flyby will shed light on what's happening beneath the moon's icy surface. With a global ocean and likely hydrothermal activity, could Enceladus have the ingredients needed to support simple forms of life?