Two Moons Quickly

NASA's Cassini spacecraft has just completed a double encounter at Saturn-- flybys of the moons Enceladus and Titan within 48 hours.

Both moons are seen as possible homes of life, even though they are extremely different worlds. Enceladus is small-- about 300 miles across-- and sheathed in ice. The most spectacular aspect of the moon is the group of geysers that erupt from its southern polar region. Scientists think there's a huge ocean of water under the ice shell, heated by internal processes and interaction with Saturn's powerful gravity. Organic compounds have been detected in the geysers' spray. Combined, those factors suggest the possibility of life in the possible ocean.

Titan, on the other hand, is huge-- bigger than Mercury, with an atmosphere denser than Earth's. It is chock full of organics, and has an active surface environment complete with weather. Many scientists see Titan as a strong possibility to harbor life.

Cassini's flybys will add more data to our understanding of those two fascinating worlds.