Potential for life on Saturn's moon: Scientists discover key organic compounds on Enceladus

The data analysis from the Cassini probe led scientists to molecular evidence crucial in the formation of life and mysterious energy necessary for its sustenance. These discoveries have been published in Nature Astronomy.

The Cassini probe, launched in 1997, was assigned to explore the mysteries of Saturn and its moon, Titan. The Cassini-Huygens mission, a collaborative project of NASA, the European Space Agency, and the Italian Space Agency, concluded successfully. It provided invaluable data about Saturn, its largest natural satellite, its rings and the geysers on Enceladus before it entered Saturn's atmosphere in 2017 and was destroyed.

Since becoming Saturn's first artificial satellite in July 2004, the Cassini probe has sent hundreds of gigabytes of data to Earth. This data has been the basis for thousands of scientific studies and continues to be utilized for discoveries.

A 2017 research indicated that the plumes of ice and steam, ejected from Enceladus’s geysers and reaching hundreds of miles, are rich in organic compounds, some of which are essential for life. A team of scientists at NASA's Jet Propulsion Laboratory, California, has now reanalyzed data from Enceladus, which is Saturn's sixth-largest moon.

The researchers found evidence of hydrogen cyanide, a key component in the formation of life. The existence of life requires amino acids, and it's one of the crucial elements in forming these amino acids. Hydrogen cyanide is versatile in its combinations, leading researchers to refer to it as a "Swiss army knife" among intermediate metabolites involved in amino acid biosynthesis.

Scientists also determined that beneath Enceladus' icy surface, there exists a source of chemical energy yet unknown to science. This energy source consists of organic compounds, including those that fuel organisms on Earth. The latest discoveries indicate that Enceladus, though seven times smaller than the Moon, could release considerably more chemical energy than previously estimated. This increases the chances of life emergence, sustenance, and replication.

"Enceladus seems to meet the basic requirements for life formation. We now have an understanding of how complex biomolecules can form there and the processes that could precede their formation," said biophysicist Jonah Peter, a doctoral student at Harvard University, who conducted most of the research at the NASA laboratory in California. The presence of hydrogen cyanide on Saturn's moon particularly intrigued Peter. "It's the starting point for most theories on the origin of life," he explained.

Previous studies in 2017 indicated the presence of chemical compounds in the ocean of Enceladus that could sustain life. The mixture of carbon dioxide, methane, and hydrogen found in the icy plumes led researchers to theorize that methanogenesis, a phase of methane fermentation resulting in methane production, could occur on Enceladus. This process, common on Earth, might have been crucial for the emergence of life here.

Peter and his team have uncovered potential sources of chemical energy on Enceladus that appear more potent than methanogenesis. This is confirmed by the discovery of oxidized organic compounds.

"If methanogenesis in terms of released energy is like a small watch battery, the energy source in Enceladus' ocean is more like a car battery. Our research suggests that this ocean would be able to provide significant amounts of energy to any potential life form," explained astrobiologist and planetary scientist Dr. Kevin Hand, a co-author of the study, from the Jet Propulsion Laboratory.

Prior studies of materials from Enceladus primarily involved laboratory experiments and geochemical modeling to emulate the conditions that Cassini encountered on Enceladus. Now, scientists have employed statistical modeling to analyze the data from the mass spectrometer onboard the probe.

"Our research shows that although the Cassini mission has come to an end, its observations continue to provide us with fresh insights about Saturn and its moons, especially Enceladus," observed planetary scientist and co-author of the study Dr. Tom Nordheim, a member of the Cassini-Huygens team.

Scientists are yet to determine whether life could or has originated on Enceladus. However, according to Jonah Peter, the new study defines the chemical processes that can be tested in laboratories to bring us closer to answering this critical question.