Re-analysis of frozen fragments of rock from one of Saturn’s rings, fed by ice vapor from the moon Enceladus, has revealed the presence of phosphorus, the only element essential to life that had not been detected before.

In any case, Enceladus quickly evolved from the status of “just another small moon of Saturn” to the status of a leader in the question: are we alone in the universe? No one thinks that intelligent beings would live there, but even a few microbes would be irrefutable proof that life is abundant and finds its way if given a chance.

Ammonia and methane ices in the clouds of the satellite confirm the presence of nitrogen and carbon in the internal ocean of Enceladus, and molecular hydrogen indicates the presence of biologically necessary energy. But there were doubts about the existence of phosphorus.

Although there are other ways for life to exist, the prospects for organisms capable of self-reproduction were greatly reduced in the absence of phosphorus. Fortunately, an article published in the “Proceedings of the National Academy of Science” removes the problem of lack of phosphorus.

“In the years since the Cassini probe visited the Saturn system, we have been repeatedly amazed by the discoveries made possible by the data collected,” admits Dr. Christopher Glein of the Southwest Research Institute. Although the existence of an internal ocean on Jupiter’s moon Europa was known long before that on Enceladus, much more is known about the composition of Saturn’s moon.

“The steam emitted by the geysers on Enceladus contains almost all the elements necessary for life as we know it,” says Glein. Phosphorus is an exception because there is no direct evidence of its existence. Missions capable of verifying the existence of phosphorus are not yet planned, but Glein and co-authors envisioned a less direct route.

Enceladus is not completely solid. Its density indicates the presence of a solid core, which probably contains all the elements of the universe necessary for life, including phosphorus. The paper models the interaction between the core and the overlying ocean to determine whether phosphates in the rocks will be released into the ocean.

In this way they learned that temperature, pressure, and acidity all corresponded to make phosphates soluble, especially in the form of orthophosphate. “The geochemistry has a simple elegance that makes the presence of dissolved phosphorus inevitable, reaching levels even higher than present-day Earth’s waters,” enthuses Glein.

This does not necessarily mean that Enceladus is inhabited; we could “impregnate” him if we wanted to. On the contrary, the absence would indicate the difficulty in the emergence of life, the fact that its presence is not inevitable on the respective worlds.

Glane puts it bluntly: “We need to go back to Enceladus to see if there’s a living ocean.”

Sources: IFL Science, New Scientist.

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• Life in the solar system? A moon of Saturn could be a good host, says a theoretical model from MIT