Discovery provides more evidence that the – ScienceDaily

Using data from NASA’s Cassini spacecraft, scientists at the Southwest Research Institute (SwRI) modeled chemical processes in the underground ocean of Saturn moon Enceladus. The studies show that a mixed metabolic schedule could support a potentially diverse microbial community in the melting water ocean beneath the frozen surface of the moon.

Prior to disinfection in September of 2017, Cassini sampled a grain of ice and water vapor exploding from cracks on the frozen surface of Enceladus, discovering molecular hydrogen, a potential food source. there for microbes. A new paper published in the journal Science planet Icarus explores other potential energy sources.

“The discovery of molecular hydrogen (H2) in the mast has shown that free energy is available in the ocean of Enceladus,” said lead author Christine Ray, who works part-time at SwRI and continues Ph.D. in physics from the University of Texas at San Antonio. “On Earth, aerobics, or breathing with oxygen, creatures consume energy in organic matter such as glucose and oxygen to create carbon dioxide and water. Anaerobic microbes can metabolize hydrogen to form methane. All life can be drawn to chemical reactions related to its imbalance between oxidant and reductant fertilizers. “

This disequilibrium creates a potential energy gradient, where redox chemistry transfers electrons between chemical species, usually with one species undergoing oxidation while another species declines. . These processes are essential for many basic tasks in life, including photo-synthesis and relief. For example, hydrogen is a source of chemical energy supporting anaerobic microbes living in the Earth’s oceans near hydrothermal fins. At the seabed on Earth, hydrothermal fins emit hot, energetic, mineral fluids that allow unique ecosystems that are infested with exotic creatures to thrive. Previous research has found growing evidence of hydrothermal fungi and chemical disequilibrium on Enceladus, which advertises at conditions living in its subterranean ocean.

“We were wondering if other types of metabolic pathways could provide energy sources in the ocean of Enceladus,” Ray said. “Because that would require a different set of oxidants that we have not yet found in the Enceladus plug, we did chemical modeling to see if the conditions in the ocean and the rocky heart could support the chemical processes. sin. “

For example, the authors looked at how ionizing radiation from space could form the oxidants O2 and H2O2, and how mature geochemistry in the ocean and rocky heart could contribute to chemical dysquilibria that may support give to metabolic processes. The team considered whether these oxidants could accumulate over time if reductions are not present in large amounts. They also considered how aqueous reductions or seabed minerals could convert these oxidants into sulfates and iron oxides.

“We compared our free energy estimates with ecosystems on Earth and concluded that, overall, our values ​​for both aerobic and anaerobic metabolism meet or exceed on the minimum requirements, “Ray said.” These results indicate that oxidant production and oxidation chemistry may contribute to supporting potential life and a diverse microbial metabolic community on Enceladus . “

“Now that we have identified food sources for microbes, the next question is to ask‘ what kind of complex organs come out of the ocean? ‘ ”SwRI Program Director, Dr. Hunter Waite, coauthor of the new paper, commented online Nature a paper by the author of Postberg et al. in 2018. “This new paper is another step in understanding how a small moon can sustain life in ways that are completely going higher than we expected!”

The results of the paper are also very important for the next generation of analysis.

“A future spacecraft could fly through the Enceladus mast to test this paper’s prediction of the amount of oxidized compounds in the ocean,” said SwRI Research Senior, Dr Christopher Glein, another coauthor. “We have to be careful, but I am delighted to think that there are strange life forms that take advantage of these energy sources that seem to be fundamental to the work of Enceladus.”

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