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- Saturn\u2019s moon Enceladus has organic molecules<\/strong> in its water vapor plumes and subsurface ocean. Could they be evidence for possible life?<\/li>\n
- A new analysis of data from the Cassini mission<\/strong> has yielded even more complex organics. They are in icy grains in both the plumes and Saturn\u2019s E ring.<\/li>\n
- The complex organics provide more evidence<\/strong> for complex chemistry and habitable conditions in the ocean below.<\/li>\n<\/ul>\n
New complex organics in Enceladus\u2019 ocean<\/h3>\n
Last month, scientists reported that organic molecules found on Saturn\u2019s moon Enceladus might be created by radiation. That\u2019s in contrast to the long-held earlier idea that they originate in a hidden ocean, below the moon\u2019s icy surface. <\/p>\n
But now, another international team of researchers has said that a new analysis of data from the Cassini mission has found new complex organics that are certain<\/em> to originate in an ocean below Enceladus\u2019 surface. The researchers said on October 1, 2025, that the organic molecules are in pristine ice grains in the water vapor plumes that Cassini flew through and analyzed. <\/p>\n
Organics in the plumes is powerful evidence for organics in an ocean below, and for complex chemistry occurring in the waters below.<\/p>\n
The ice grains in the plumes are being ejected from large cracks in the icy surface of Enceladus. Scientists call these cracks tiger stripes. The ice grains were ejected only minutes before hitting Cassini\u2019s Cosmic Dust Analyzer (CDA) instrument. This meant they were as fresh as could be expected.<\/p>\n
The research team published their peer-reviewed findings in Nature Astronomy<\/em> on October 1, 2025.<\/p>\n
Organic molecules in plumes and the E ring<\/h3>\n
Scientists already knew the plumes contained organics since Cassini first flew through them back in 2008. Later analysis showed there were various kinds of organics, both simple and more complex. Cassini also found them in Saturn\u2019s E ring, which consists of particles from the plumes.<\/p>\n
Lead author Nozair Khawaja at Freie Universit\u00e4t Berlin in Germany said:<\/p>\n
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Cassini was detecting samples from Enceladus all the time as it flew through Saturn\u2019s E ring. We had already found many organic molecules in these ice grains, including precursors for amino acids.<\/p>\n<\/blockquote>\n
One problem with the organics in the E ring, however, is that those molecules can already be quite old, even hundreds of years old. This means they could have been altered by radiation in Saturn\u2019s magnetosphere. Their composition might be significantly different from when they were freshly ejected into space.<\/p>\n
![\"Graphic](\"https:\/\/earthsky.org\/upl\/2025\/10\/organic-molecules-ice-grains-ocean-plumes-Enceladus-ESA-October-1-2025.jpg\")
View larger. | This graphic depicts how organic molecules in the subsurface ocean make their way through the tiger stripes cracks in the ice crust and condense onto ice grains in the water vapor plumes. Image via NASA\/ JPL-Caltech\/ ESA.<\/figcaption><\/figure>\n Pristine organics in Enceladus\u2019 plumes<\/h3>\n
So how could scientists study the organic molecules in their original state? By analyzing those in the plumes, of course. The ones in the plumes just erupted from the ocean below, through the tiger stripes. They were the most pristine that Cassini could ever sample.<\/p>\n
Indeed, Cassini had already analyzed some of those organics. The results showed evidence of a variety of organics, as well as water, salts, ammonia, nitrogen, oxygen, phosphorus, hydrogen cyanide and methane. There was even evidence for active hydrothermal activity on the ocean floor, much like on Earth.<\/p>\n
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? The discovery of new complex organic molecules at Saturn’s #Enceladus enhances the likelihood that the moon is habitable ?On Earth, these molecules are involved in chemical reaction chains that lead to the more complex molecules essential for life.Read more ? www.esa.int\/Science_Expl\u2026? ? ??<\/p>\n
\u2014 ESA Space Science (@science.esa.int) 2025-10-01T09:09:47.185Z<\/p>\n<\/blockquote>\n
Speed matters<\/h3>\n
But now, the new analysis results take that a step further. And as it turns out, the speed<\/em> of the ejected molecules makes a difference. It has to do with how fast the molecules hit Cassini\u2019s Cosmic Dust Analyzer instrument. The faster, the better, as Khawaja explained:<\/p>\n
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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\u2019t cluster, and we have a chance to see these previously hidden signals.<\/p>\n<\/blockquote>\n
Old and new organic molecules<\/h3>\n
The re-analysis of the Cassini data yielded interesting results. Scientists had previously found some of the organics in the fresh ice grains in grains in the E ring. This, the researchers said, confirms that they originated in Enceladus\u2019 ocean. Co-author Frank Postberg at Freie Universit\u00e4t Berlin added:<\/p>\n
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These molecules we found in the freshly ejected material prove that the complex organic molecules Cassini detected in Saturn\u2019s E ring are not just a product of long exposure to space, but are readily available in Enceladus\u2019s ocean.<\/p>\n<\/blockquote>\n
In addition, the researchers also found new kinds of organic molecules they\u2019d not seen before. These included complex chemicals including liphatic, (hetero)cyclic ester\/alkenes, ethers\/ethyl and, tentatively, nitrogen- and oxygen-bearing compounds. That is significant, since on Earth they are part of chemical reactions that lead to even more complex organic molecules needed for life. This increases the chances of the ocean being habitable, as Khawaja noted:<\/p>\n
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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. 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.<\/p>\n<\/blockquote>\n
![\"Black](\"https:\/\/earthsky.org\/upl\/2025\/10\/Nozair-Khawaja-Freie-Universitat-Berlin.jpg\")
Nozair Khawaja at Freie Universit\u00e4t Berlin in Germany is the lead author of the new study about organics on Enceladus. Image via Freie Universit\u00e4t Berlin.<\/figcaption><\/figure>\n A return to Enceladus?<\/h3>\n
Cassini ended its mission to Saturn way back in 2017. But scientists with ESA are now planning a new mission, to launch in the early 2040s. This time, the spacecraft would actually land on Enceladus and take samples to analyze.<\/p>\n
In the meantime, scientists can still compare the new analysis results with those from other icy moons of Saturn and Jupiter. ESA Cassini project scientist Nicolas Altobelli said:<\/p>\n
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It\u2019s fantastic to see new discoveries emerging from Cassini data almost two decades after it was collected. It really showcases the long-term impact of our space missions. I look forward to comparing data from Cassini with data from ESA\u2019s other missions to visit the icy moons of Saturn and Jupiter.<\/p>\n<\/blockquote>\n
Even if we don\u2019t find evidence of life on Enceladus, there would still be a lot to learn about the conditions in its ocean, and perhaps the oceans on other icy moons in the solar system. Khawaja said:<\/p>\n
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Even not finding life on Enceladus would be a huge discovery, because it raises serious questions about why life is not present in such an environment when the right conditions are there.<\/p>\n<\/blockquote>\n
![\"Graphic](\"https:\/\/earthsky.org\/upl\/2025\/10\/Enceladus-mission-concept-orbiter-lander-ESA-October-1-2025.png\")
View larger. | Mission concept for new Enceladus orbiter and lander mission by ESA, to launch in the early 2040s. Image via ESA.<\/figcaption><\/figure>\n Organics on Enceladus: Ocean or radiation?<\/h3>\n
The new study is also interesting with regard to another study published last month. That one, presented at Europlanet\u2019s EPSC-DPS Joint Meeting 2025 in Helsinki, Finland, on September 9, 2025, postulated that organics on Enceladus\u2019 surface and in its plumes could be created by radiation in Saturn\u2019s magnetosphere. Those organics included carbon monoxide, cyanate, ammonium and the precursors to amino acids.<\/p>\n
This new study, however, published in Nature Astronomy<\/em> on October 1, 2025, details the additional new organics found in the plumes, including the complex compounds listed above. The researchers are confident that they originate in the ocean. So who is right? Or could it be both? Perhaps some organics are the results of radiation, but others do come from the ocean below.<\/p>\n
As happens all the time in science, there are competing hypotheses. But that\u2019s how science works. It will be very interesting to see what else researchers discover about the organics on Enceladus and what they might tell us about the habitability \u2013 and perhaps even life itself \u2013 of this fascinating little world.<\/p>\n
Bottom line: A new analysis of data from the Cassini mission has found more complex organics in Enceladus\u2019 ocean. They hint at complex chemistry and potential habitability.<\/p>\n
Source: Detection of organic compounds in freshly ejected ice grains from Enceladus\u2019s ocean<\/p>\n
Via European Space Agency<\/p>\n
Read more: Complex organics on Enceladus: A clue to possible life?<\/p>\n
Read more: Signs of life on Enceladus might remain hidden in its ocean<\/p>\n
- A new analysis of data from the Cassini mission<\/strong> has yielded even more complex organics. They are in icy grains in both the plumes and Saturn\u2019s E ring.<\/li>\n