"Swiss army knife" of life and energy buffet found on Saturnian moon
The most promising places to look for life beyond Earth might not be Mars but icy moons orbiting gas giants. Saturn’s moon Enceladus has just climbed the list, as NASA data reveals it’s home to a molecule thought to be key to the origin of life, and suggests there’s more chemical energy for life to chow down on than we thought.
Enceladus might not seem too inviting – it looks like a big snowball. But beneath that icy shell is a deep global ocean that’s surprisingly cosy for life thanks to hydrothermal vents and, it turns out, a veritable buffet of ingredients important for life. Over the years scientists have detected complex organic molecules, phosphorus and other compounds that life requires – as well as methane, which could be emitted by microbes snacking on this stuff. In another study, scientists exposed Earthly microbes to these conditions and found they thrived.
Analyzing data gathered by NASA’s Cassini probe, the new study lends even more weight to Enceladus’s potential habitability for some forms of life. First, the team detected hydrogen cyanide, a molecule considered the starting point for most theories of how life got started here on Earth. The researchers call it a kind of Swiss army knife because of how versatile this molecule is in forming amino acids, which are the building blocks of life.
The team also discovered evidence that chemical energy sources on Enceladus are far stronger and more diverse than previously known. In 2017 scientists found evidence of potential life-sustaining chemistry called methanogenesis, consisting of carbon dioxide, methane and hydrogen. In the new study, the researchers found a variety of organic compounds that were oxidized, a process that helps release chemical energy in larger amounts.
“If methanogenesis is like a small watch battery, in terms of energy, then our results suggest the ocean of Enceladus might offer something more akin to a car battery, capable of providing a large amount of energy to any life that might be present,” said Kevin Hand, co-author of the study.
The scientists note that the chemical pathways suggested in this study could be tested in the lab. As the case for life on Enceladus continues to get stronger, more work will no doubt be focused on this strange Saturnian moon.
The research was published in the journal Nature Astronomy.