By BlueShift and AFP | 2025-10-28

Scientists sifting through data collected by the Cassini spacecraft have discovered fresh evidence that Saturn’s moon Enceladus could have all the right ingredients to host extraterrestrial life.

In a study published October 1 in Nature Astronomy, researchers said they have discovered new complex organic molecules spewing from Enceladus.

This indicates that complex chemical reactions are taking place within its underground ocean, they said. Some of these reactions could be part of chains that lead to even more complex, potentially biologically relevant molecules.

Just 500km wide, the white, scar-covered Enceladus is one of hundreds of moons orbiting Saturn, the sixth planet from the sun. Scientists once believed it was too far away from the sun, and therefore too cold, to be habitable.

Then the Cassini orbiter flew past the moon several times during a 2004-2017 trip to Saturn and its rings, discovering evidence that a vast saltwater ocean is concealed under the moon's kilometers-thick layer of ice.

By studying the data collected by Cassini, scientists found that Enceladus's ocean has many of the elements thought to be needed to host life, including salt, methane, carbon dioxide and phosphorus.

When the spacecraft passed over the moon's south pole, it discovered jets of water bursting through cracks on the surface.

These jets were propelling tiny ice particles -- smaller than grains of sand -- into space. While some of these ice grains fell back to the moon's surface, others collected around one of Saturn's many rings.

The Cassini mission

The Cassini mission to study Saturn and its complex system of rings and moons was a joint endeavor of NASA, the European Space Agency (ESA), and the Italian space agency (ASI).

Cassini's Huygens probe, built by ESA, parachuted to the surface of Saturn’s largest moon, Titan, in January 2005, in the most distant landing to date in our solar system, returning spectacular images and other scientific findings.

Key discoveries during Cassini's 13 years at Saturn, which concluded in September 2017, included a global ocean with strong indications of hydrothermal activity within Enceladus and liquid methane seas on Titan.

When Cassini flew through Saturn's outermost "E" ring, it was "detecting samples from Enceladus all the time," said planetary scientist Nozair Khawaja of the Free University of Berlin, who is the new study's lead author.

By looking through these samples, scientists had previously identified numerous organic molecules, including the precursors of amino acids, which are fundamental building blocks of life.

But these ice grains could have been altered after being trapped in the ring for hundreds of years or beaten up by blasts of cosmic radiation, so they wanted to look at some fresh ice grains.

Scientists had access to some fresh ice grains already, collected by Cassini's Cosmic Dust Analyzer when the orbiter flew directly into the spray spewing from the moon's surface in 2008.

But it took years to complete a detailed chemical analysis of these particles.

Case for another probe

Study co-author Frank Postberg said the research proves that "the complex organic molecules Cassini detected in Saturn's E ring are not just a product of long exposure to space, but are readily available in Enceladus's ocean."

To get the best idea about what is happening on Enceladus, a mission would need to land near the icy geysers and collect samples, said French astrochemist Caroline Freissinet, who was not involved in the study.

Reporting the discovery on its website, the ESA said this finding further strengthens the case for a dedicated ESA mission to orbit and land on Enceladus.

"Enceladus ticks all the boxes to be a habitable environment that could support life," it said.

"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," Khawaja said.