© 2012, 2011 WGBH Educational Foundation. All Rights Reserved.

Adapted from NOVA: "Finding Life Beyond Earth." Third party materials courtesy of Cassini Imaging Team/SSI/JPL/ESA/NASA, NASA/JPL-Caltech, NASA/JPL/GSFC/SwRI/SSI, NASA/JPL/Space Science Institute/Universities Space Research Association/Lunar and Planetary Institute.