Hydrothermal Activity on Saturn's Moon Enceladus May Mean Life

It is well known that Saturn's moon Enceladus harbors a subsurface ocean, but what scientists have just discovered are signs of current hydrothermal activity that may be warming up its seas enough for life to survive.

Hydrothermal activity occurs when seawater penetrates and reacts with a rocky crust and then becomes a heated, mineral-laden solution. This phenomenon is seen in the deep oceans on Earth, and now NASA's Cassini spacecraft has found the first clear evidence of it on Enceladus as well.

"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 in Washington, said in a news 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."

Scientists first realized that Enceladus might be a hotspot for life in 2005 when Cassini's Cosmic Dust Analyzer (CDA) detected microscopic grains of rock, rich in silicon, spewing out from geysers on the moon's surface. This suggests that the tiny particles are grains of silica, which on Earth, are mostly formed from hydrothermal activity.

According to the researchers, Enceladus has active hydrothermal vents at the bottom of its cold sea - hidden by layers of ice - and that the heat from those vents warms the ocean to a temperature that could even sustain life. Specifically, this process would require temperatures of at least 194 degrees Fahrenheit (90 degrees Celsius), meaning this icy moon may be hotter than we previously thought.

"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," said lead author Sean Hsu, at the University of Colorado at Boulder.

Previously reported in the journal Geophysical Research Letters, Cassini scientists have also found noteworthy amounts of methane in the atmosphere - another possible indicator of hydrothermal activity or possibly the melting of ice rich in methane.

"This moon has all the ingredients - water, heat, and minerals - to support habitability in the outer Solar System, confirming the astrobiological potential of Enceladus," Cassini project scientist Nicolas Altobelli told the National Monitor.

The latest findings were published Wednesday in the journal Nature.

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