From Michelle Starr at ScienceAlert:
These findings bolster the hypothesis that, deep under its icy crust, Enceladus could be harbouring simple marine life, clustered around the warmth of hydrothermal vents.
Previously, simple organic molecules detected on the little moon were under around 50 atomic mass units and only contained a handful of carbon atoms.
“We are, yet again, blown away by Enceladus,” said geochemist and planetary scientist Christopher Glein of the Southwest Research Institute.
“We’ve found organic molecules with masses above 200 atomic mass units. That’s over ten times heavier than methane.
“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.”More.
Abstract: Saturn’s moon Enceladus harbours a global water ocean1, which lies under an ice crust and above a rocky core2. Through warm cracks in the crust3 a cryo-volcanic plume ejects ice grains and vapour into space4,5,6,7 that contain materials originating from the ocean8,9. Hydrothermal activity is suspected to occur deep inside the porous core10,11,12, powered by tidal dissipation13. So far, only simple organic compounds with molecular masses mostly below 50 atomic mass units have been observed in plume material6,14,15. Here we report observations of emitted ice grains containing concentrated and complex macromolecular organic material with molecular masses above 200 atomic mass units. The data constrain the macromolecular structure of organics detected in the ice grains and suggest the presence of a thin organic-rich film on top of the oceanic water table, where organic nucleation cores generated by the bursting of bubbles allow the probing of Enceladus’ organic inventory in enhanced concentrations. (paywall)
At this point, it will be just as interesting if Enceladus has “all of the basic requirements for life as we know it” but does not have life. That would cast doubt on the thesis that life naturally evolves when the conditions are right. Of course, we will need quite a few examples to be sure.
Notes re Enceladus from NASA:
Overview: For decades, scientists didn’t know why Enceladus was the brightest world in the solar system, or how it related to Saturn’s E ring. Cassini found that both the fresh coating on its surface, and icy material in the E ring originate from vents connected to a global subsurface saltwater ocean that might host hydrothermal vents.
♦ Saturn’s moon Enceladus is a small, icy body, but Cassini revealed this ocean world to be one of the solar system’s most scientifically interesting destinations.
♦ Cassini discovered that geyser-like jets spew water vapor and ice particles from an underground ocean beneath the icy crust of Enceladus.
♦ With its global ocean, unique chemistry and internal heat, Enceladus has become a promising lead in our search for worlds where life could exist.
Before Cassini arrived at the Saturn system, planetary explorers only had hints that something interesting might be happening at Enceladus. Pictures from the Voyager spacecraft in the 1980s indicated that although this moon is small—only about 310 miles (500 kilometers) across—its icy surface is remarkably smooth in some places, and bright white all over. In fact, it’s the most reflective body in the solar system.
See also: Looking for life in all the hard places – a guidebook Researcher: “We are using Earth to guide our search for life on other planets because it is the only known example we have,” said Timothy Lyons, a distinguished professor of biogeochemistry and director of the Alternative Earths Astrobiology Center.
Could alien life be buried in ET oceans?