Microbes Could be Right at Home on Saturn’s Moon Enceladus

Enceladus could harbor alien life, at least in the form of microbes, according to a new study, examining how microbes react to conditions thought to exist on this small moon of Saturn. Since the arrival of the Voyager spacecraft in the 1980’s, astronomers have known that this small satellite was home to mighty oceans of water hidden beneath its icy surface.

Single-celled methanogenic (methane producing) microorganisms called Methanothermococcus okinawensis were tested to see how they would survive under the harsh conditions seen at Enceladus. With their simple design, these lifeforms flourished in the wet, hot conditions.

“Methanogenic archaea are among the organisms that could potentially thrive under the predicted conditions on Enceladus, considering that both molecular hydrogen (H2) and methane (CH4) have been detected in the plume,” researchers wrote in the journal Nature Communications.

The plumes of Enceladus
An illustration of the Cassini spacecraft diving through the jets of salty water erupting from the south pole of Enceladus. Photo: NASA/JPL-Caltech

Geyser-like jets expel water vapor and ice into the space around Saturn, suggesting a large amount of energy is present in the oceans, likely provided by heat within the alien moon being expelled into the oceans by hot hydrothermal vents. These geysers were discovered by the Cassini spacecraft, as it carried out the most extensive study, to date, of Saturn and its moons.

On Earth, these microorganisms are typically found near hydrothermal vents, converting hydrogen gas and carbon dioxide into methane.

“We conclude that some of the CH4 (methane) detected in the plume of Enceladus might, in principle, be produced by methanogens,” the international team of investigators reported.

Warmth from the moon, together with vast storehouses of liquid water, provide Enceladus with two key ingredients thought necessary to support alien lifeforms. This experiment shows that simple life could thrive on this world of water and ice, but provides no evidence that intelligent life may have arisen on this moon, which whizzes 180,000 km (112,500 miles) above the cloud tops of Saturn.

The hydrogen required to drive the life processes could be produced by chemical reactions happening under the frozen crust of Enceladus, the team concluded.

Saturn is the second-largest planet in the Solar System and is host to dozens of moons. In 2007, Cassini arrived at Saturn, on a mission to explore the gas giant, together with its family of satellites and magnificent system of rings. When the orbiting observatory looked at Enceladus, the magnetometer revealed that something – likely an atmosphere – was pushing against the planet’s magnetic field near the tiny moon.

On further investigation, astronomers found salty water was continually erupting from vents on the moon, shooting out into space at velocities of nearly 1,300 KPH (800 MPH). Reaching space, the material freezes, forming Saturn’s E ring. Analysis of that ring shows it is composed, in part, of silica nanograins, which can only be produced at temperatures above 90C (200F), providing evidence for geothermal vents beneath the ocean, much like those seen on Earth. The venting emanates from the moon’s southern pole.

Enceladus is only 500km (310 miles) in diameter, but it reflects more light back from its surface than any other body in the Solar System, due to its smooth, ice-covered surface.


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