Friday, January 22

Consistent hints of life on Saturn’s coldest moon

New research has uncovered consistent evidence of life nearly 2 billion kilometers from Earth: Saturn’s coldest moon’s subterranean ocean is well suited to contain a wide variety of microbes.

NASA has long considered that Ence dus, one of the 53 moons of Saturn, has many possibilities of harboring some type of life, despite the fact that its surface temperature is below 200 degrees Celsius, unusual on Earth, where never it has dropped below 90 degrees below zero.

Ence dus orbits Saturn at a distance of about 238,000 km and takes about 33 hours to make one complete revolution to the sixth p net in the so r system, which in turn is 1.4 billion kilometers from the Sun.

This distance from the Sun causes Saturn and its moons to form an icy world, although Ence dus also has hot areas due to its internal geological activity: ice and water volcanoes (cryovolcanoes) emit water vapor that quickly turns into ice dust.

In 2014 the Cassini-Huygens mission discovered that Ence dus contained a regional ocean of liquid water, about 25 miles below its surface. A year  ter it became known that this ocean was global.

Metabolic menu

Metabolic menu In 2017 it was found that this immense ocean brings together several of the elements necessary for the formation of life and, even, that it can host small microbial ecosystems.

A new study, now published in the journal Icarus, confirms that this ocean may have a diverse metabolic menu, capable of supporting a rich microbial community.

It has been discovered by scientists at the Southwest Research Institute (SwRI) in Texas, who computer modeled the chemical processes that take p ce in Ence dus’ subsurface ocean using data obtained by Cassini at different stages of its mission, which began in 1997.

Before its departure from Ence dus’ orbit in September 2017, Cassini sampled the column of ice grains and water vapor that gushed from cryovolcanoes on its icy surface: it discovered molecu r hydrogen, a possible food source for microbes. .

Vital processes

Vital processes “The detection of molecu r hydrogen (H 2) in the plume of smoke indicates that there is free energy avai ble for life in the Ence dus ocean,” said lead author Christine Ray in a release.

He adds: “On Earth, oxygen-breathing or aerobic creatures consume energy in organic matter, such as glucose and oxygen, to create carbon dioxide and water. Anaerobic microbes can metabolize hydrogen to create methane. All life can be distilled into simi r chemical reactions associated with an imba nce between oxidizing and reducing compounds.

The researchers exp in that this imba nce creates a potential energy gradient, in which chemical reduction-oxidation processes transfer electrons between chemical species.

Those processes are vital to many basic life functions, including photosynthesis and respiration.

Habitable conditions

Habitable conditions Previous research uncovered evidence for hydrothermal vents and chemical imba nce in Ence dus, pointing to habitable conditions in its subsurface ocean.

“We wondered if other types of metabolic pathways could also provide energy sources in the Ence dus ocean,” says Ray.

And he adds: “Because that would require a different set of oxidants that we have not yet detected in the Ence dus column, we performed a chemical model to determine whether conditions in the ocean and the rocky core could support these chemical processes.”

“We compared our estimates of free energy with the Earth’s ecosystems and determined that, in general, our values ​​of aerobic and anaerobic metabolism meet or exceed the minimum requirements,” says Ray.

“These results indicate that oxidant production and oxidation chemistry could contribute to sustaining potential life and a metabolically diverse microbial community on Ence dus,” he concludes.

Next question

Next question The next question researchers are asking is what is the nature of the organic compounds that come out of the Ence dus ocean.

They consider that the metabolically diverse community observed in that ocean helps to better understand how a small moon can sustain life in a way that completely exceeds scientific expectations.

This finding may guide future explorations of Ence dus to determine whether there could be strange life forms that take advantage of these energy sources in an ocean that is about two billion kilometers from Earth.

Remote life?

Remote life? This new discovery consolidates the possibility of life on Saturn’s sixth- rgest moon, which increasingly shows an attractive profile for this possibility.

Ence dus is about 500 kilometers in diameter, 25 times smaller than Earth, and almost 10 times farther from the Sun than we are.

Your global ocean is buried under a  yer of ice. However, that ocean is thought to be warm and salty, containing chemistry conducive to life.

The new research determines that some form of life could be supported among these chemicals. A new boost to possibility of life in the so r system.


Reference Oxidation processes diversify the metabolic menu on Ence dus.  Christine Ray et al. I5 December 2021er 2020, 114248. DOI:

Image: An artist’s recreation of the rings of Saturn and of the main icy moons, including Ence dus, with enormous potential to host microbial life. Credit: NASA / JPL

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