Could life exist on Saturn's moon Enceladus?

Saturn has 146 confirmed moons, far more than any other planet in the solar system, and one of them deserves special attention. We're talking about Enceladus, which is only 313 miles (504 kilometers) in diameter. Scientists think it has everything it needs to support life, writes Fabian Klenner, a planetary scientist and astrobiologist at the University of Washington (Washington).

From 2004 to 2017, Cassini, a joint mission of NASA, the European Space Agency and the Italian Space Agency, explored Saturn, its rings and moons and produced very interesting results, according to which Enceladus harbors an ocean of liquid water under the icy crust of Enceladus. In addition, it is known that geysers at the south pole of this satellite eject gas and ice particles formed from ocean water into space.

Like Earth's oceans, Enceladus' ocean contains salt, most of which is sodium chloride, commonly known as table salt. The ocean also contains various carbon-based compounds and undergoes a process called tidal heating that generates energy on the moon. Liquid water, carbon-based chemistry and energy are the key ingredients of life, the scientist writes. It turns out that this satellite has all three.

In 2023, Klenner and other scientists discovered phosphate, another compound essential to supporting life, in ice grains originating from Enceladus' ocean. Phosphate, a form of phosphorus, is also important for all life on Earth: it is found in DNA, cell membranes and bones. This was the first time scientists had discovered this compound in an extraterrestrial water ocean.

No one has yet been able to discover life beyond the Earth. However, scientists agree that Enceladus is a very promising place to search for life.

Where should this search start?

In a paper published in March 2024, Klenner and colleagues tried to see if the spacecraft's dust analyzer instruments could detect and identify traces of life in ejected ice grains on Enceladus. They found that the tools they used to do this were good at identifying cellular material. Instruments designed to analyze individual ice grains should be able to identify bacterial cells, even if an ice grain from a geyser like Enceladus contains only 0.01% of the components of a single cell.

The special dust analyzer on Cassini did not have the analytical capabilities to identify cellular material in ice grains. However, scientists are already developing instruments with much greater capabilities for potential future missions to Enceladus. The results of Klenner and his colleagues' experiments will serve as the basis for planning and designing these tools.

According to Klenner, Enceladus is one of the main targets of future missions from NASA and the European Space Agency. In 2022, NASA announced that the mission to Enceladus has the second highest priority when selecting the next major missions—the mission to Uranus has the highest priority.

The European Agency recently announced that Enceladus is the main target of its next big mission. This mission will likely include a high-throughput dust analyzer to analyze ice grains.

It should be noted that Enceladus is not the only moon with an ocean of liquid water. Jupiter's moon Europa also has an ocean that covers the entire moon beneath its icy crust. Europa's ice grains float above the surface, and some scientists believe Europa may even have Enceladus-like geysers that shoot grains into space.