Signs of Life on Saturn's Moon?

USA TODAY

Saturn's geyser-spewing moon, Enceladus — visited by the international Cassini spacecraft on its closest flyby this week— presents planetary scientists with a geophysical locked-room mystery.

Whodunit? Or rather Whatdunit? Or Whatizit?

How does something buried inside an ice ball only 311 miles wide, provide the pop to propel a plume 600 miles out of the moon's south pole? "The biggest puzzle with Enceladus is where is the heat source," says Cassini scientist Linda Spilker of NASA's Jet Propulsion Laboratory, which manages the mission. "This tiny moon 'should' be frozen over like the others orbiting Saturn."

And there is one even more compelling question.

"Is it possible for life to exist on Enceladus, the tiny icy satellite of Saturn," asked planetary scientists Susan Kieffer of the University of Illinois and Bruce Jakosky of the University of Colorado, in the journal Science last year. Life on Enceladus, hidden in an interior lake or ocean suspected under its ice, has consumed planetary researchers since 2005, when Cassini first spotted the plume.