Ingredients for life found on strange Saturn moon
By Will Dunham
WASHINGTON (Reuters) - The basic ingredients for life -- warmth, water and organic chemicals -- are in place on Saturn's small moon Enceladus, scientists said on Wednesday in detailing the content of huge plumes erupting off its surface.
The scientists described observations made by the Cassini spacecraft when it flew over the surface of Enceladus on March 12 as part of an ongoing exploration of Saturn and its moons.
Scientists working on the joint U.S.-European mission did not say they had detected any actual evidence of life on this moon where geysers at its south pole continuously shoot watery plumes some 500 miles off its icy surface into space.
But they said the building blocks for life were there, and described the plumes as a surprising organic brew sort of like carbonated water with an essence of natural gas.
"Water vapor was the major constituent. There was methane present. There was carbon dioxide. There was carbon monoxide. There were simple organics and there were more complex organics," Hunter Waite of the Southwest Research Institute in San Antonio, Texas, told reporters.
Organic molecules contain carbon-hydrogen bonds and can be found in living things.
Waite said the material bursting out of the geysers was very much like a comet's chemistry. Comets are celestial bodies orbiting the sun made of rock, dust and ice with characteristic tails of gas and dust streams.
"The question that one would ask is: where did the organics come from?" Waite said.
"Of course, natural gas comes from decaying biological matter on Earth. But this is not the conclusion we reached for Enceladus. Another possibility is the geochemistry going on in the interior can also produce organics," Waite added.
Scientists are eager to learn whether conditions exist in our solar system other than Earth to support life, even in merely microbial form. Mars has been the subject of a lot of investigation, but some moons also are seen as candidates.
"We see on Enceladus the three basic requirements for the origin of life," Larry Esposito of the University of Colorado said. "We see water, although it may not be liquid. We see organic compounds ... and we also have a source of heat."
"Now we don't yet see, nor can we tell or state, whether the interior of Enceladus contains liquid water, and if that water might be a habitat for life," Esposito added, adding that future fly-bys will examine that question, starting in August.
Some scientists think the source of the geysers may be heated liquid water -- perhaps even an ocean -- under the surface of Enceladus (pronounced en-SELL-ah-dus).
The scientists said Cassini found higher temperatures than previously known at the south pole surface, although still frigid at minus-135 degrees Fahrenheit (minus-93 degrees C).
Cassini was about 120 miles above the surface as it flew through a plume. Enceladus has a diameter of 310 miles
and is one of Saturn's innermost moons.