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Seeds of life found near Saturn

Image: Enceladus
A sniff test of water vapor spewing from Saturn's moon Enceladus shows it is gushing with organic molecules, increasing the possibility of life existing somewhere in the Saturn system.
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A sniff test of water vapor spewing from Saturn's moon Enceladus shows it is gushing with organic molecules, increasing the possibility of life existing somewhere in the Saturn system.

Scientists have been intrigued by the moon since the fountain of water was first spotted in 2005. Now they've identified a soup of prebiotic material there, similar to what's found in comets, from an analysis of data collected by the Cassini spacecraft.

Nobody really knows how life began, but astrobiologists guess it required chemicals like those tasted by Cassini, a little liquid water and some unknown spark.

Hunter Waite, a Cassini principal investigator at the Southwest Research Institute (SWRI) in San Antonio, said Enceladus' newly understood composition should stir up previous notions of Saturn and its moons.

"These findings will definitely get people to ask new questions about the formation of the Saturn system," Wait told "The astrobiological potential of the Saturn system just went up a notch or two."

Cassini made its observations during a high-speed pass 30 miles above Enceladus on March 12, and recorded the highest temperatures yet detected near tiger stripe-like fissures on the icy moon's southern pole.

Waite and other scientists released their early findings about Enceladus' thermal activity and icy plume composition during a briefing today at NASA headquarters in Washington, D.C.

Big comet?
The new heat maps of Enceladus' surface show temperatures higher than previously observed in the south polar region, with hot tracks running the length of giant fissures.

"They're still awfully cold, but much warmer than background temperatures of the rest of the surface," said John Spencer, a Cassini scientist at SWRI in Boulder, Colo. "This means it has to be even warmer under the surface and raises the possibility of liquid water beneath the [exterior]."

Cassini measured the fissures to be -135 degrees Fahrenheit (-93 degrees Celsius) near their centers. That's about 63 degrees F warmer than previously observed and some 200 degrees F (93 degrees C) warmer than the rest of the moon's surface.

Scientists also say Cassini sampled organic chemicals during its bath in the icy jets and that they are similar to those found in comets.

"A completely unexpected surprise is that the chemistry of Enceladus, what's coming out from inside, resembles that of a comet," Waite said, but noted that Enceladus is also very different from a comet. "Comets have tails and orbit the sun, and Enceladus' activity is powered by internal heat while comet activity is powered by sunlight."

Organic steam bath
In addition to carbon dioxide, carbon monoxide and other compounds, Waite said organic molecules such as methane, propane, acetylene and formaldehyde were sniffed in Enceladus' icy plumes.

"Enceladus' brew is like carbonated water with an essence of natural gas," Waite said of the moon's steamy jets. "Astrobiologically speaking, this moon is one of the most interesting places in the solar system."

Dennis Matson, Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif., said all of the ingredients for life could be present beneath Enceladus' pockmarked surface.

"Enceladus has got warmth, water and organic chemicals," said Dennis Matson. "These three basic ingredients provide a minimum for the origin of life."

But Matson said Cassini will have to gather more data before a key element — liquid water — can be verified to exist on the moon.

"We ... [can't tell] whether the interior of Enceladus contains liquid water and if that water might be a habitat for life," Matson said during today's briefing, "but these are the questions that Cassini will focus on in future flybys."

The spacecraft is set to revisit Enceladus in August and October of this year, followed by five more flybys in the next two years.