Documentary about the Cassini-Huygens spacecraft's seven year journey to Saturn's largest moon, Titan, which scientists think may hold clues to how life began here on Earth. In January 2005, the probe plummeted down to the surface, surviving a fiery entry and with its parachutes safely deployed. Titan was revealed as a place that does look a lot like home, but one whose surface is made of ice, where river channels are gouged by liquid methane rain, and volcanoes belch out subzero liquid water.