In 2008, Cassini completed several "flybys" of Enceladus, including one on October 9 that brought the spacecraft to within just 16 miles of the moon's surface -- the closest flyby yet of any Saturn moon. Thanks to Cassini's cameras and instruments, these flybys gave researchers a closer look at the plumes. Scientists from NASA's Jet Propulsion Laboratory, the University of Colorado, and the University of Central Florida teamed up to analyze both the water vapor plumes and the ice particles being ejected from the moon. Their conclusion? That the plumes may come from a liquid water source beneath the surface of Enceladus. According to the scientists, the geysers' behavior supports a mathematical model that treats the vents as nozzles that channel water vapor from a liquid reservoir to the moon's surface at supersonic speeds. The team's findings were reported in the November 27 issue of the journal Nature.