The discovery of life-sustaining phosphates in the subterranean ocean on Enceladus, one of Saturn’s moons, is the first of its kind in the universe. The researchers write that no scientists have ever detected phosphates in an ocean beyond Earth in a newspaper article nature.
As it passed Enceladus, one of Saturn’s moons, the Cassini spacecraft collected ice grains from plumes sprouting from a suspected subsurface ocean. Because of all this liquid water, the icy moon is, according to experts, one of the most promising locations for extraterrestrial life in our solar system.
If the oceans on Enceladus contained the dissolved salts and organic compounds that contributed to the cataclysmic chemical processes of life on Earth, then it is entirely conceivable that such life originated there as well. The same goes for the moon Europa, which orbits Jupiter.
Phosphates play an important role in the chemistry of life. Phosphate is present in the cells of all living things and contributes to the growth, development and reproduction of those cells, among other things. It’s no wonder that phosphates appear in foods like cheese, milk, nuts, and legumes, but also in animal feed and crop manure, among other things.
Unexpectedly a lot
“We already expected that phosphates would be present in the oceans on Enceladus,” says planetary researcher Stephanie Cazaux of Delft University of Technology, who was not involved in the study. Phosphates previously appeared in material returned by the Japanese space probe Hayabusa2 from a distant asteroid Ryugu. Previous measurements from Cassini itself also indirectly suggested that there could be phosphates in the subsurface ocean on Enceladus.
“However, I didn’t expect there to be so many of them,” says Casaux. Based on their analysis, the researchers estimate that the concentration of phosphates on Enceladus may be about a hundred times higher than in Earth’s oceans. This makes no difference what kind of life might be present – that life then got used to high concentrations of phosphate.
“We can only explain this chemically if Enceladus arose in a very cold place, with lots of water and carbon dioxide.”2ice, in the outer regions of the solar system,” says Casaux. “I find the coloring of the history of this icy moon, and what that implies for how other icy moons in the solar system formed, very interesting.”
ancient puzzle pieces
Remarkably, the discovery has only been made now, while Cassini has not been active since 2017. After the probe ran out of fuel, the Cassini spacecraft was sent into Saturn’s atmosphere, where it burned up.
Stéphanie Cazaux: “This research was done using old puzzle pieces, with data from the archives. This now provides such an outstanding insight. This is very special and shows how long science will enjoy a mission like Cassini.”
In the meantime, she and others are already working on potential future missions to the icy moon, though major space agencies haven’t yet planned those missions — they’ll first visit the icy moons around that other gas giant from the solar system with Jupiter. Icy Moon Explorer.
Kazaux: “At TU Delft, we’re already working on robots that can stick to ice and that we can use to climb through cracks on the surface of Enceladus. Ultimately, we still want to know if there is anything alive.”
Phosphates and the environment
Although phosphates are important to life on Earth, an excess can, paradoxically enough, lead to environmental problems. For example, if excess phosphate ends up in ditches and rivers after over-fertilization, this wealth of nutrients can cause algae and duckweed to spread. This then blocks, among other things, the light for further life. Too much phosphate sometimes leads to an imbalance in the Earth’s ecosystem.
The fact that there are up to a hundred times more phosphates on the surface of Enceladus than there is on Earth does not mean that any of the inhabitants of Enceladus live in a polluted environment. The ecosystem on Enceladus – if it exists – would have a very different balance: life on it would get used to high concentrations of phosphates.
