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Extraterrestrial life: we should be searching on Enceladus

Geysers on Encelade / Credits: Nasa

Humanity may not need to look too far to detect the presence of life “elsewhere in the universe”, according to recent research. Enceladus, Saturn’s moon, could harbour conditions that are ideal for supporting unicellular microorganisms. 

Along with Europe, Jupiter’s moon, it is possible that Enceladus is our best chance of being able to one day detect extraterrestrial life. Enceladus contains a liquid ocean on its surface which could effectively harbour unicellular microorganisms known as archaea, found in some of the Earth’s most extreme environments, as can be read in a recent publication in Nature Communications. A methanogenic archaeon -called Methanothermococcus okinawensis -can also survive in laboratory conditions simulating an icy moon environment.

On Earth, we find this type of archeon developing at very high temperatures near deep hydrothermal vents. They convert carbon dioxide and hydrogen into methane. What we need to remember is that traces of methane have also been detected by the Cassini probe in the vapours emanating from fissures on the surface of Enceladus. “We conclude that some of the CH4 [methane] detected in the plume of Enceladus might, in principle, be produced by methanogens”, explain the researchers. However, they also note that sufficient hydrogen to support such microbes could be produced via geochemical processes in the rock core of the moon.

So let’s be clear: the data gathered in laboratories does not confirm that there is in fact life on Enceladus, but that the conditions appear to be favourable for supporting the presence of methanogenic archaea. “Our study only concerns microorganisms, and I want to avoid any speculation about intelligent life”, notes Simon Rittman of the University of Vienna. In relation to methane on Enceladus, further research is obviously needed in order to rule out geochemical rather than biological causes.

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