Interest in Enceladus as a potential host for alien life likely to intensify as tests demonstrate Earth bacteria thrive in similar conditions
Deep-sea bacteria thrive in conditions designed to closely match those on Saturn’s tiny moon, Enceladus, according to scientists investigating possibilities for alien life sorts to survive there.
The findings are likely to intensify those who are interested in Enceladus, which has risen to the top of the list of potential locations in our solar system that might have the right conditions to support extraterrestrial life. Last year Nasa announced that a flyby of Enceladus by the Cassini spacecraft had identified water, ice and most of the chemical ingredients necessary for habitability.
The Cassini spacecraft, which flew through a plume of vapour erupting from fissures in the moon’s icy surface, exposed the presence of hydrogen, which points to the existence of active energy sources on the moon’s ocean floor, similar to the hydrothermal vents that teem with life on Earth.
The microorganisms found on Earth, known as methanogenic archaea, utilize carbon dioxide and hydrogen as fuel and release methane as a byproduct. Traces of methane were also picked up by the Cassini probe, although it was impossible to tell whether these were linked to biological or geochemical reactions.
Now scientists have tested whether some of the microbes found in the Earth’s ocean vents, known as methanogens, could survive the conditions likely to be found on Enceladus. In hypothesi at least, the scientists observed they can.
Simon Rittmann, a biologist who led the work on the University of Vienna, said:” We’ve extended the boundaries within which we know methanogens can live .”
In designing the simulations, a challenge was the limited information about the conditions on Europa. Cassini’s observations demonstrate there is a liquid brine ocean, but scientists don’t know the ocean depth- which determines pressure- the temperatures around the vents and many details of the ocean chemistry.
So Rittmann and colleagues simulated a wide range of conditions, for instance varying pressure from three bars( shallow water) to 90 bars( virtually 1km depth ).
One of the deep-sea organisms tested, called Methanothermococcus okinawensis , prospered irrespective of the pressure, temperature, whether it was given vitamins or not and whether it was exposed to toxic chemicals such as formaldehyde, ammonia, or carbon monoxide gas. When placed in the most extreme conditions, the bacteria entered a nation of dormancy, and reactivated within got a couple of seconds once they were returned to a more favourable environment.
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