Although a few years ago it was not a particularly interesting moon, since it is barely 500 kilometers in diameter and looks like a huge snowball, the truth is that Enceladus is quite a discovery and as we investigate a little more in it, it becomes more fascinating becomes. Now, using mass spectrometry from NASA’s Cassini spacecraft, a team of scientists has discovered carbon-rich organic molecules ejected from cracks in Enceladus’ icy surface. Thus, the saltwater plumes that sprout from this snowy moon have just gathered one of the most important ingredients for habitability: large organic molecules rich in carbon. Enceladus is presented as a promising place to host alien life.
“Once again, Enceladus has impressed us. We had previously only identified the simplest organic molecules that contained a few carbon atoms, but even that was very intriguing,” said Christopher Glein, a space scientist specializing in extraterrestrial chemistry at the Soutwest Research Institute (SwRI ).
But these are huge, complex molecules.
“Now we have found organic molecules with masses greater than 200 atomic mass units. That is more than ten times heavier than methane. With complex organic molecules emanating from its ocean of liquid water, this moon is the only body besides the Earth that satisfies all the basic requirements for life as we know it “, clarifies Glein in the journal Nature that publishes the study.
These findings reinforce the hypothesis that, deep within its icy crust, Enceladus could be home to simple marine life, clustered around the warmth of hydrothermal vents.
Thanks again, Cassini
Before the Cassini spacecraft disintegrated after many years of intense and fruitful work, it sampled the column of material emerging from the subsurface of Enceladus. The SwRI-led Cosmic Dust Analyzer and Neutral and Ionic Mass Spectrometer made measurements both within Saturn’s column and in Saturn’s E ring, which is made up of ice grains escaping from Enceladus’ gravity.
“Even after its end, the Cassini spacecraft continues to teach us Enceladus’ potential to advance the field of astrobiology in an ocean world ,” says Glein.
Last year, Cassini data revealed the presence of molecular hydrogen in the plumes on Enceladus’ surface – a possible source of what ocean water would be reacting with rocks through hydrothermal processes.
The warmth of the vents allows a different process to take place: chemosynthesis. Bacteria around the vents harness chemical energy to produce sugar molecules, food .
“ Hydrogen provides a source of chemical energy that sustains microbes that live in Earth’s oceans near hydrothermal vents, ” says Hunter Waite, co-author of the work. “Once you have identified a possible food source for microbes, the next question to ask is ‘ what is the nature of complex organic compounds in the ocean? ‘ This paper represents the first step in that understanding: complexity in organic chemistry beyond our expectations. “
According to experts, the next interesting step would be to send a spacecraft to fly through Enceladus’ plume and analyze those complex organic molecules using a high-resolution mass spectrometer to help scientists determine how they were created.
“We must be cautious, but it is exciting to think that this finding indicates that biological synthesis of organic molecules in Enceladus is possible, ” says Glein.
Meanwhile, researchers here on Earth continue to observe and experiment at hydrothermal vents in hopes of advancing our understanding of what life would be like on the fascinating moon Enceladus.
Referencia: Macromolecular organic compounds from the depths of Enceladus, Nature, www.nature.com/articles/s41586-018-0246-4
