An illustration shows the hydrothermal activity on Saturn's moon Enceladus. Photo by NASA/JPL-Caltech
WASHINGTON, March 12 (UPI) -- NASA's Cassini probe has evidence of active hot-water chemistry on Saturn's moon Enceladus. It's the first confirmation of hydrothermal activity beyond planet Earth.
"These findings add to the possibility that Enceladus, which contains a subsurface ocean and displays remarkable geologic activity, could contain environments suitable for living organisms," John Grunsfeld, astronaut and associate administrator of NASA's Science Mission Directorate, said in a press release.
"The locations in our solar system where extreme environments occur in which life might exist may bring us closer to answering the question: Are we alone in the universe," Grunsfeld added.
The evidence is described in two recently published scientific papers. The first, published this week in the journal Nature, includes observations related to soil grains in Enceladus' atmosphere. Detailed analysis of the grains suggests they formed as minerals, were deposited by warm water as it rose and came into cooler water above. Researchers say the temperatures required to produce the tiny rock grains seen on the moon's surface and its atmosphere would need to be at least 194 degrees Fahrenheit.
"It's very exciting that we can use these tiny grains of rock, spewed into space by geysers, to tell us about conditions on -- and beneath -- the ocean floor of an icy moon," explained Sean Hsu, lead study author and a postdoctoral researcher at the University of Colorado at Boulder.
The second paper, published recently in the journal Geophysical Research Letters, describes the methane-rich composition of the plume of gas and ice particles that regularly erupts from the moon's southern pole. As part of the study, scientists built models to explain the high concentration of methane in the plumes -- as discovered in previous samples collected by Cassini.
The model that most matched the reality of those samples posits hydrothermal activity as the cause. High pressure in Enceladus' deep sea, the study suggests, produces icy materials called clathrates. When clathrates form, models predict they would entrap methane molecules within ice water crystals. These crystals are then blasted into space, releasing copious amounts of methane.
"We didn't expect that our study of clathrates in the Enceladus ocean would lead us to the idea that methane is actively being produced by hydrothermal processes," said lead author Alexis Bouquet, a grad student at the University of Texas at San Antonio.
