Enceladus (Image Credit: NASA/JPL)

Enceladus, one of Saturn’s largest moons, is often looked over in favor of the Jovian moon, Europa, when there’s some indication that it might be more conducive for microbial life-forms.

However, if a new study is correct, Enceladus might finally surpass Europa in scientific curiosity. Researchers from the University of Colorado, Boulder, have published research that suggests hydrothermal activity may be brewing deep within the interior of this Saturnian moon.

According to the paper—published earlier this month in ‘Nature,’ after four painstaking years of analysis—evidence of this activity can be found within the microscopic grains of rock detected by the Cassini probe. Using Cassini data in conjunction with lab work and computer simulations, the likely origin of these grains were determined.

In the corresponding press release, the team describes the process through which these grains arise, first “seawater infiltrates and reacts with a rocky crust, before emerging as a heated, mineral-laden solution.” The water would need to be quite hot—around 194 degrees Fahrenheit (90 degrees Celsius)—to make this scenario possible, which requires some internal source of heat beyond tidal friction.

This diagram shows how the interior of Enceladus might look (Credit: NASA/JPL)

Moreover, “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 Sean Hsu, a research associate with CU Boulder’s Laboratory for Atmospheric and Space Physics, and the lead author of the paper.

How We Know:

The specks were originally picked up by one of Cassini’s instruments, the Cosmic Dust Analyzer (CDA), in 2004. Careful analysis indicated that the rocks contained significant concentrations of silicon: an element forged by hydrothermal forces found in great abundance on Earth (found in sand, for instance). In fact, roughly 90 percent of Earth’s crust is composed of silicates.

Before determining the source, numerous hypotheticals had to be ruled out.

“We methodically searched for alternate explanations for the nano-silca grains, but every new result pointed to a single, most likely origin,” said Frank Postberg, a Cassini CDA team scientist at Heidelberg University in Germany, and a co-author on the paper. They expand:

With help from researchers from the University of Tokyo, the team ran a number of simulations, hoping to give credence to, or completely rule out, their hypothesis. Specifically, they wanted to know under what condition small silica grains—those that match Enceladus’ in size—are forged. If non-hydrothermal activity was at work, one would expect the grains to be composed of water-ice instead of silica.

“Ten years ago it was a big mystery why the nano-grains were made of silica rather than water ice,” Kempf said. “Now we know the observations were correct. We know where the silica particles are coming from, and why we are seeing them. We learned something very unexpected, which is why I really like this study.”

One unexpected find was just how treacherous their journey tends to be. Of course, the grains originate on the seafloor, before being forced upward. Once they exit the interior through geysers, they are flung more than 30 miles (50 kilometers) into space, where they languish for a few years. Any longer and they would be much larger.

While tentative, these findings are very promising indeed. Also, we should note that in the past, astronomers have asserted that Europa might have a similar set up.

SEE ALSO: Gemini Observatory in Hawaii Captures Powerful, Bright Volcanic Eruptions on Jupiter’s Moon, Io


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