Scientists have not solved the mystery of methane on Mars yet and another exciting mystery of the gas from one of Saturn’s 82 moons, Enceladus, is here to tease them. The amount of methane on Enceladus, which is otherwise unexplainable, indicates that the existence of life on Saturn’s moon is “very likely," scientists say.
In 2005, NASA’s Cassini probe found ice and methane on Enceladus. When scientists analysed the observations made by the spacecraft, they found that a liquid ocean existing below the surface of Enceladus. Methane was found in the plumes rising from the surface. For years, scientists have been studying and guessing the origin of the gas. In nature, methane is mainly produced by living organisms, such as humans and animals, when they digest food, or when bacteria eat and decompose organic matter. Some geochemical processes also produce methane, however, their contribution is very low compared to what living beings produce. The methane on Enceladus though is not in such a low amount.
To know if microbes living in the undersea were at the core of high amounts of methane, scientists need to send a probe equipped to do the task. However, scientists thought of a way around it. Researchers at the University of Arizona calculated probabilities for all the possible known sources of methane using new mathematical models on the data collected by Cassini.
The findings are exciting and mysterious. Scientists concluded that the plumes are either the result of microbial hydrothermal vent activity, in which microbes eat dihydrogen produced by hydrothermal vents — fissures in the sea bottom, or some other mysterious process that is never seen on Earth.
According to scientists, even the highest possible estimate of methane produced from known non-living processes is far less than the concentration of methane found in plumes. Scientists claim that Cassini’s observations are consistent with an environment habitable for life.
“Obviously, we are not concluding that life exists in Enceladus’ ocean," said Regis Ferriere, one of the two lead authors of the study, in a statement. However, he believes that the existence of life on Enceladus is “very likely." The study was published on June 7 in Nature Astronomy.