“NASA’s Cassini spacecraft has provided scientists the first clear evidence that Saturn’s moon Enceladus exhibits signs of present-day hydrothermal activity which may resemble that seen in the deep oceans on Earth,” NASA announced yesterday.
What is “hydrothermal activity,” you might ask?
The space agency describes it as the natural occurrence here on Earth “when seawater infiltrates and reacts with a rocky crust and emerges as a heated, mineral-laden solution.” Here is a brief video that visualizes the process:
Now, spacecraft Cassini has transmitted data that provides a first clear indication that the icy Enceladus moon may have similar ongoing, active processes, which create an environment friendly to life. In other words, there are most likely warm (even hot) oceans underneath the icy moon surface.
The key finding that led to this conclusion was the frequent detection of “miniscule rock particles rich in silicon” by Cassini‘s cosmic dust analyzer (CDA) instrument – even before it entered Saturn’s orbit in 2004.
After an extensive, four-year analysis, scientists determined that these miniscule rocks (the largest of which were 6 to 9 nanometers) are most likely grains of silica, which are the result of hydrothermal activity and can be found in sand and mineral quartz on Earth.
“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 the paper’s lead author Sean Hsu, a postdoctoral researcher at the University of Colorado at Boulder.
According to the paper, the tiny grains of silica only form when “hot water containing dissolved minerals from the moon’s rocky interior travels upward, coming into contact with cooler water.”
“We methodically searched for alternate explanations for the nanosilica grains, but every new result pointed to a single, most likely origin,” said co-author Frank Postberg, a Cassini CDA team scientist at Heidelberg University in Germany.
Postberg was able to confirm the theory when colleagues at the University of Tokyo performed laboratory experiments that validated the hydrothermal activity hypothesis. In fact, they were able to verify the conditions under which silica grains formed at the exact same size Cassini detected around Saturn.
John Grunsfeld, astronaut and associate administrator of NASA’s Science Mission Directorate in Washington concluded that, “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.”
“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.”
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