Mystifying organic molecules discovered erupting from Enceladus: ScienceAlert

Mystifying organic molecules discovered erupting from Enceladus: ScienceAlert

Enceladus doesn’t look very chronological. It’s monochromatic and rather small, and pales in comparison to Saturn’s large, showy rings and giant hexagon.

But as many Solar System objects demonstrate, appearances can be very deceiving. Enceladus has a lot more going for it than an initial glimpse might indicate. A new analysis suggests that the icy world harbors far more organic molecules than previous findings indicate.

A closer look at data from Saturn’s Cassini probe revealed that Enceladus is spewing molecules like methanol, ethane and molecular oxygen from geysers bubbling up from liquid water deep within its icy shell.

It’s a discovery that leans further into the idea that the moon could support some kind of biochemistry, or even communities of microbes, in its global surroundings — adding support to calls to send a dedicated mission to Enceladus in the hope of finally discovering it. Finding extraterrestrial life.

“The results presented here suggest that Enceladus hosts a multi-phase, compositionally diverse chemical environment consistent with a habitable subsurface ocean,” wrote a team led by astrobiologist Jonah Peter of Harvard University and NASA’s Jet Propulsion Laboratory.

“The (chemical) species identified in this work also suggest that this ocean may contain the necessary building blocks needed to synthesize compounds important for the origin of life.”

Previously unidentified organic molecules on Enceladus indicate a habitable environment. (Peter et al., Nat. Astron., 2023)

Most of what we know about Enceladus comes from the Cassini mission, which explored Saturn and its moons from 2004 to 2017. We didn’t know much about the small, icy moon before then; But then the probe detected plumes of fog emerging from cracks in Enceladus’ icy surface and flew through them, revealing a flowing liquid ocean below.

Subsequent analysis of data collected by Cassini’s ion and neutral mass spectrometer (INMS) instrument revealed the presence of organic molecules in those plumes – water, carbon dioxide, methane, ammonia and molecular hydrogen.

But INMS has low mass accuracy, which makes identification of less abundant species difficult, because there is a very wide range of possible groups that can fit the data. So the complete composition of the columns remained an open question.

Peter and his colleagues, planetary scientist Tom Nordheim and astrobiologist Kevin Hand of JPL, took another swing at the data from IMNS. They used statistical modeling to compare the data to a large library of known mass spectra to determine what could produce the patterns seen in the Cassini data.

Their results confirmed previous findings while also revealing a wider range of organic molecules than first identified, including hydrogen cyanide, acetylene and propylene. Compounds involved in prebiotic chemistry – the chemistry that leads to the formation of life.

We have some compelling evidence that Enceladus has an active hydrothermal environment. It orbits Saturn, causing the moon to expand and compress, heating its interior. This thermal energy can escape through holes in the ocean floor, providing a hospitable environment for life, even far from the sun. We know this, because it happens deep in the Earth’s oceans.

We can’t know at this point whether what we’ve discovered so far means there is life on Enceladus. It could just be a bunch of molecules, hanging out by chance. But the exciting thing is that it can be really important. We can conduct laboratory experiments here on Earth to try to determine whether or not Enceladus is inhabited, but really, the only way we’ll know for sure is to explore further.

There are currently some proposed missions for Enceladus, but nothing has been decided yet. However, every drop of evidence brings us one step closer to visiting that strange moon and searching for those strange bacteria.

“Our results suggest the existence of a chemically rich and diverse environment that could support complex organic synthesis and perhaps even the origin of life,” the researchers wrote.

What the hell are we waiting for?

Their findings have been published in Nature astronomy.

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