A new study reports that methane emitted by Enceladus may indicate life in the subterranean seas of Saturn’s moons.
In 2005, NASA’s Cassini Saturn orbiter discovered that geysers ejected water ice particles from cracks in the “tiger pattern” near Enceladus’ south pole into space. This material forms a column that provides energy for Saturn’s E ring (the second outermost ring on the planet), which is believed to come from a huge ocean of liquid water splashing under the moon’s icy crust.
There is more than ice water in the column. During several nearby flights from Enceladus, 313 miles (504 kilometers), Cassini also discovered many other compounds, for example dihydrogen (H2) and various carbon-containing organic compounds, including methane (CH4).
Photo: Enceladus, Saturn’s cold and bright moon,
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Dihydrogen and methane are of particular interest to astrobiologists. Scientists say that H2 may be produced by the interaction of Enceladus’s seafloor rocks and warm water, which indicates that the moon has deep-sea hydrothermal vents-this environment may have been the cradle of life on earth.
In addition, it is called methane During the production process, H2 provides energy for some terrestrial microorganisms that produce methane from carbon dioxide. A similar thing may happen on Enceladus, especially since Cassini also detected carbon dioxide and surprisingly abundant methane in the lunar pillar.
“We want to know: Can terrestrial microorganisms that’eat’ dihydrogen and produce methane explain the large amount of methane detected by the Cassini?” Regis, co-author of the study and associate professor in the Department of Ecology and Evolutionary Biology at the University of Arizona · Ferrière (Regis Ferrière) said in a statement.
Ferrière and his colleagues established a series of mathematical models to evaluate the probability of bio-production of Enceladus. These simulations are diverse. For example, the team investigated whether the observed H2 production can sustain the Enceladus microbial population, and how this population will affect the rate of H2 and methane escape into the column.
“In short, we can not only assess whether Cassini’s observations are compatible with the habitable environment for life, but we can also quantitatively predict the expected observations if methane production does occur on the seafloor of Enceladus.” Ferrier Say. Chapter
This evaluation should please those of us who are expecting something to swim in Enceladus’s icy and dark ocean. The team determined that the chemical reaction of the non-biological hydrothermal event (without the help of life) that we know on Earth does not explain the methane concentration observed by the Cassini. However, the contribution of adding methanogenic microorganisms fills this gap well.
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To be clear: this new study published in the journal Nature Astronomy last month does not claim life on Enceladus. Researchers say that, for example, the cold moon may have some abiotic reactions that produce methane that are not common on Earth, perhaps the decay of the original organic matter left after the moon was born. In fact, if Enceladus was formed by a comet-rich material rich in organic matter, then the latter hypothesis would be very suitable, as some scientists believe.
“First of all, this is partly due to the possibility that we think there are different hypotheses,” Ferrière said. “For example, if we think that the possibility of life on Enceladus is extremely low, then those alternative non-biological mechanisms will become more likely, even if they are very strange compared to what we know on Earth.”
In other words, “biomethane production seems to be in line with the data,” Ferrièr added. “In other words, we cannot rule out the possibility of the’life hypothesis’ being very small. To reject the life hypothesis, we need more data from future tasks.”