Methane spreading over Saturn’s sixth moon reveals it may be there life on Enceladus, or better, life swarms in the sea beneath the surface of Saturn’s moon, reports a new study.
In 2005, the Cassini Saturn orbiter NASA discovered geysers that launched water ice particles from fractures in the “tiger stripe” near the south pole of Enceladus into space.
According to scientists, that material, which forms a plume that powers Saturn’s E ring (the planet’s second outermost ring), is thought to come from a huge ocean of liquid water flowing under the frozen shell of the moon.
Further studies revealed that there is not only water ice in the plume, in fact during numerous close flyovers of the 313 miles (504 kilometers) wide Enceladus, Cassini also identified many other compounds, for example dihydrogen monoxide (H2) and a variety of organic compounds containing carbon, including the methane (CH4).
Dihydrogen monoxide and methane are particularly intriguing to astrobiologists, as it is likely produced by the interaction of rock and warm water at the bottom of the sea of Enceladus, the scientists said, suggesting that the moon has deep-water hydrothermal vents. same kind of environment that may have been the cradle of life here on Earth.
Additionally, dihydrogen monoxide provides energy to some terrestrial microbes that produce methane from carbon dioxide, in a process called methanogenesis. Something similar could happen on Enceladus, especially considering that Cassini also spotted carbon dioxide, and a surprising amount of methane, in the lunar plume.
“We wanted to know: Could Earth-like microbes that ‘eat’ hydrogen and produce methane explain the surprisingly large amount of methane detected by Cassini?”
stated in a note the lead author of the study Régis Ferrière, associate professor in the Department of Ecology and Evolutionary Biology at the University of Arizona.
So Ferrière and his colleagues built a series of mathematical models that evaluated the probability that there was life on Enceladus, and that the methane was biologically generated.
These simulations were different, with the team investigating whether the observed H2 production could sustain a population of microbes, and how that population affected the rate at which H2 and methane escaped into the plume.
“In summary, not only can we assess whether Cassini’s observations are compatible with a habitable environment for life, but we could also make quantitative predictions on the predicted observations, if methanogenesis were to actually occur on the seabed of Enceladus”
So can we actually say from the studies that there may be life on Enceladus?
This assessment should cheer up those of us who are hoping that there is indeed life on Enceladus, and something swims in the cold, dark sea of Saturn’s sixth largest moon.
The team determined that abiotic (without the help of life) hydrothermal chemistry as we know it on Earth does not explain very well the methane concentrations observed by Cassini, however the addition of the contributions of methanogenic microbes bridges the gap well.
To be clear: the new study, published last month in the magazine Nature Astronomy, he does not claim that life exists on EnceladusIn fact, the researchers said it could be possible that the frozen moon has some types of abiotic reactions that produce methane that are not prevalent here on Earth, such as the decay of primordial organic matter left over from the moon’s birth.
Indeed, the latter hypothesis would fit well if Enceladus had formed from material rich in organic substances supplied by comets, as some scientists believe.
“Partly it boils down to how likely it is that we believe there may be various assumptions, for example, if we believe that the probability of life on Enceladus is extremely low, then such alternative abiotic mechanisms become much more likely, even if they are very alien to what we know here on Earth.“
That said, “biological methanogenesis appears to be compatible with the data,” added Ferrièr. “In other words, we cannot dismiss the ‘life hypothesis’ as highly improbable. To reject the life hypothesis, we need more data from future missions ”.
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