When it comes to habitable places in our solar system, the tiny moons of Saturn don’t seem likely candidates. Yet time and time again, they’ve proven themselves to be exciting places for life. Europa, Titan, and Enceladus all have a claim to potential habitability. A new study just made Enceladus even more interesting.

In 2005, Cassini found the first evidence that Enceladus has a hidden ocean beneath its icy surface. After that, Enceladus has teased scientists for years with its spectacular plumes. Chemical analyses showed that this alien ocean contained salts and simple organic molecules. Already, you’ve got water, salt, and organic molecules necessary for life.
But it gets better.
Scientists, re-examining data from NASA’s Cassini mission, have identified a fresh batch of organic molecules bursting from Enceladus’s depths, including types never before seen there. They found esters, which give fruits their smell on Earth. They also observed ethers and alkenes, crucial chemical connectors, and other complex molecules containing nitrogen and oxygen. In other words, the chemistry on Enceladus looks even more promising for life.
Old Ice, New Ice
The new study is an analysis of already existing data. The Cassini spacecraft orbited Saturn for 13 years, and its Cosmic Dust Analyzer (CDA) was designed to scoop up tiny dust and ice particles and analyze what they were made of.
On one of its 22 fly-bys of Enceladus, a maneuver codenamed “E5,” Cassini did something unique: it flew faster and closer than ever before, plunging through the densest part of the plumes at a staggering speed of nearly 18 kilometers per second (over 40,000 miles per hour). This speed was key.
Jets of water burst from cracks in Enceladus’ South Pole all the time. Some of them fall back onto the moon’s surface, while others escape and form a ring around Saturn that traces Enceladus’ orbit. Smaller than grains of sand, some of the tiny pieces of ice fall back onto the moon’s surface, whilst others escape and form a ring around Saturn that traces Enceladus’s orbit. Scientists call this the E ring.
“Cassini was detecting samples from Enceladus all the time as it flew through Saturn’s E ring. We had already found many organic molecules in these ice grains, including precursors for amino acids,” says lead author Nozair Khawaja.

The ice grains in the ring can be hundreds of years old. They have been weathered and may have undergone chemical changes. Scientists wanted fresh grains. This is where the E5 mission came into play. It gathered particles straight from Enceladus, not from the ring. This speed made another key difference. At lower velocities, when the CDA instrument captured ice grains, the impact was relatively gentle. The water molecules in the ice would often clump together, creating “water-cluster species” that could mask the signals of the more interesting organic compounds hidden within.
“The ice grains contain not just frozen water, but also other molecules, including organics. At lower impact speeds, the ice shatters, and the signal from clusters of water molecules can hide the signal from certain organic molecules. But when the ice grains hit CDA fast, water molecules don’t cluster, and we have a chance to see these previously hidden signals.”
Tantalizing Chemistry
So, what are these new molecules, and why do they matter so much?

The study confirmed the presence of compounds seen before, like aryl groups (ringed structures like benzene) and other simple oxygen-bearing molecules. But the new detections have opened up entirely new possibilities for the chemistry of Enceladus.
One group includes esters and alkenes. On Earth, esters are known for creating the pleasant smells of fruits like pineapples and pears. In biology, they form the chemical bonds in lipids, the molecules that make up cell membranes. Alkenes are highly reactive molecules that are key intermediates in the synthesis of more complex organic structures.
They also found strong evidence for ethers and ethyl groups. Ethers are molecules in which an oxygen atom acts as a bridge between two carbon chains. This structure makes them excellent building blocks for larger, more complex macromolecules. The detection of these compounds hints that Enceladus’s ocean can create the organics and link them together.
Perhaps most tantalizingly, the analysis revealed complex spectra that suggest the presence of molecules containing both nitrogen and oxygen. This includes possible derivatives of compounds like pyrimidine, a core component of the nucleobases in DNA and RNA. While the data isn’t sharp enough to identify specific molecules like thymine, the fragments strongly suggest a rich chemistry involving nitrogen, an absolutely essential element for life as we know it.
What Does This All Mean?

All this reads a bit like “tell me you found life on Enceladus without telling me.” Sure, there are other plausible mechanisms through which these molecules could be there. There isn’t any smoking gun for evidence of life. But all of this fits perfectly well with a habitable subsurface ocean.
“There are many possible pathways from the organic molecules we found in the Cassini data to potentially biologically relevant compounds, which enhances the likelihood that the moon is habitable,” says Nozair. “There is much more in the data that we are currently exploring, so we are looking forward to finding out more in the near future.”
Based on what we know now, it appears that Enceladus has all the necessary ingredients for life. We know it has a liquid water ocean. We know that ocean is salty and in contact with a rocky core. And we have strong evidence for hydrothermal vents — cracks in the moon’s seafloor where hot, mineral-rich water churns up from the interior, creating chemical energy.
Here on Earth, such vents are vibrant ecosystems, powered not by sunlight but by chemical reactions. They are considered one of the most likely places for life to have originated. The detection of these new, relatively complex organic molecules on Enceladus suggests that similar life-powering chemistry could be happening right now, 800 million miles away.
The Legacy of Cassini
The Cassini mission officially ended in 2017 when the craft plunged into Saturn’s atmosphere, but its legacy is a gift that keeps on giving. The data it collected continues to be a treasure trove. But if we want to truly confirm whether Enceladus has life, we will need to go back with a new generation of tools designed for that specific purpose.
Cassini was a scout, and an excellent one at that. It proved that Enceladus is a habitable world, but its instruments weren’t built to find inhabitants. A future mission would need to be a dedicated astrobiology probe, one that could analyze freshly-plucked ice grains with even greater sensitivity, or maybe even dive into the planet.
The study was published in Nature.