A recent study of Enceladus, one of Saturn’s moons, has detected several organic compounds that had never been recorded there before. The findings, published this month in Nature Astronomy, provide new clues about the interior chemical composition of this icy world, as well as new hope that it could harbor life.
The researchers analyzed data from the Cassini probe, which launched in 1997 and studied Saturn and its moons for years until its destruction in 2017. For Enceladus, Cassini gathered data from ice fragments forcefully ejected from the moon’s subsurface ocean up into space.
Enceladus is one of 274 bodies so far discovered in Saturn’s gravitational pull. It measures about 500 kilometers in diameter, making it the planet’s sixth-largest satellite. While this moon does not stand out for its size, it is notable for its cryovolcanoes—geysers at Enceladus’s south pole that spew out water vapor and ice fragments. Plumes of ejected material can extend to nearly 10,000 kilometers in length, which is more than the distance from Mexico to Patagonia, and some of this material rises into space. The outermost of Saturn’s main rings—its E ring—is primarily made up of ice ejected into space by Enceladus.
This material is believed to come from a saline water chamber beneath the moon’s icy crust that is connected to its rocky core. It’s possible that chemical reactions are taking place down there, under high pressure and heat.
Until now, most chemical analyses of ice from Enceladus were of particles deposited in Saturn’s E ring. But during a high-speed flyby of the moon in 2008, Cassini was fortunate enough to directly sample freshly ejected fragments from a cryovolcano. The new research paper reanalyzed this data, confirming the presence of previously detected organic molecules, as well as revealing compounds that had previously been undetected.
“Such compounds are believed to be intermediates in the synthesis of more complex molecules, which could be potentially biologically relevant. It is important to note, however, that these molecules can be formed abiotically as well,” Nozair Khawaja, a planetary scientist at Freie Universität Berlin and lead author of the study, told Reuters. The discovery significantly expands the range of confirmed organic molecules on Enceladus.
The key is that the compounds appeared in freshly ejected particles, suggesting that they were formed within the moon’s hidden ocean or in contact with its internal interfaces, not during their journey through the E ring or via exposure to the conditions of space. This reinforces the hypothesis that hydrothermal processes beneath Enceladus’s surface could be generating rich organic chemistry. Combining this new research with previous studies, scientists have now found five of the six elements essential for life—carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur—in the satellite’s ejected material.
This itself is not a discovery of life, nor of biosignatures—the signs of life. However, the research confirms that Enceladus has the three basic conditions for life to form: liquid water, an energy source, and essential elements and organics. “Enceladus is, and should be ranked, as the prime target to explore habitability and search whether there is life or not,” Khawaja said.
This story originally appeared on WIRED en Español and has been translated from Spanish.
