Researchers, who used data from the NASA’s Cassini spacecraft, think chemical reactions between the moon’s rocky core and warm water from its subsurface ocean are linked to these complex molecules. “We are, yet again, blown away by Enceladus. Previously we’d only identified the simplest organic molecules containing a few carbon atoms, but even that was very intriguing,” said Christopher Glein, a space scientist from Southwest Research Institute in the US. “Now we’ve found organic molecules with masses above 200 atomic mass units. That’s over ten times heavier than methane,” said Glein.
“With complex organic molecules emanating from its liquid water ocean, this moon is the only body besides Earth known to simultaneously satisfy all of the basic requirements for life as we know it,” he said. Prior to its deorbit in September of 2017, Cassini sampled the plume of material emerging from the subsurface of Enceladus. The Cosmic Dust Analyser (CDA) and the SwRI-led Ion and Neutral Mass Spectrometer (INMS) made measurements both within the plume and Saturn’s E-ring, which is formed by plume ice grains escaping Enceladus’ gravity. “Even after its end, the Cassini spacecraft continues to teach us about the potential of Enceladus to advance the field of astrobiology in an ocean world,” Glein said.
During Cassini’s close flyby of Enceladus on in 2015, researchers detected molecular hydrogen as the spacecraft flew through the plume. Previous flybys provided evidence for a global subsurface ocean residing above a rocky core. Molecular hydrogen in the plume is thought to form by the geochemical interaction between water and rocks in hydrothermal environments. “Hydrogen provides a source of chemical energy supporting microbes that live in the Earth’s oceans near hydrothermal vents,” said Hunter Waite, from Southwest Research Institute.
“The paper’s findings also have great significance for the next generation of exploration,” Glein said. “A future spacecraft could fly through the plume of Enceladus, and analyse those complex organic molecules using a high-resolution mass spectrometer to help us determine how they were made,” he said. “We must be cautious, but it is exciting to ponder that this finding indicates that the biological synthesis of organic molecules on Enceladus is possible,” he added.