Enceladus’s plumes. Image: NASA/JPL/Space Science Institute
Now, scientists which refer to Enceladus as a hot spot in the search for alien life have discovered how certain methane-producing microbes on Earth, have the ability to survive extremely harsh conditions which may exist on Enceladus.
Furthermore, scientists explain how methane found around Enceladus’ surface may have been produced by microbial life, located just beneath its icy crust.
According to the cited scientific publication, prokaryotic microorganisms known as methanogenic archaea could develop under certain conditions assumed on Enceladus, using carbon dioxide and molecular hydrogen for growth, releasing methane.
Enceladus as seen from afar across Saturn’s rings. Image: NASA/JPL/Space Science Institute
“I’m pleased people are starting to take deep looks at biological methane production,” says Christopher Glein, a geochemist and planetary scientist at the Southwest Research Institute speaking to WIRED. “The next step is doing this hard work in the lab to figure out what life might look like from a spacecraft instrument’s point of view.”
To reach this conclusion, a team of researchers from the University of Vienna cultivated three of these microorganisms in the laboratory, under gas compositions and pressures similar to those attributed to Enceladus. One of the microbes, called Methanothermococcus Okinawensis, grew and produced methane, even in the presence of components that inhibited the growth of other methanogenic archanes, such as ammonia, carbon monoxide or formaldehyde.
This graphic shows how Cassini scientists think water interacts with rock at the bottom of the ocean of Saturn’s icy moon Enceladus, producing hydrogen gas.
In addition, scientists found that serpentinization – a process in which rocks are geochemically altered – that possibly occurred in the Enceladus nucleus, could generate enough hydrogen to support these prokaryotic microorganisms.
The recently obtained results support the idea that methanogenic archaea could, in theory, develop and produce methane in Enceladus. However, experts warn that methane can also be generated by geochemical, not biological, processes.
To find out whether or not Enceladus may in fact be an alien homeworld, “Future missions to Enceladus or other icy moons should be equipped to be able to detect methanogenic biosignatures related to methanogens, like certain lipids or ratios of certain carbon isotopes,” said study co-author Simon Rittmann, of the Department of Ecogenomics and Systems Biology at the University of Vienna in Austria, in an interview with space.com
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