That means Enceladus has the only ocean beyond Earth known to contain all six elements needed for life.

The claimed discovery of dissolved sodium phosphate, announced in a report published Wednesday in the journal Nature, makes Enceladus all the more intriguing in the search for habitable worlds beyond Earth.

The report is based on data from an instrument on board NASA’s Cassini spacecraft, which explored Saturn and its moons for 13 years before engineers sent it plunging into the gas giant’s atmosphere in 2017.

“We now really have found that Enceladus’s subsurface ocean is the most habitable place in the solar system, at least as far as we know,” said lead author Frank Postberg, a professor at the Free University of Berlin.

“But that doesn’t mean that it’s actually hosting life, that it’s inhabited,” he added.

Modest in size at just a few hundred miles in diameter, Enceladus seems to have what scientists call a “soda ocean” — carbonated, bubbly, salty. Postberg suggests it might taste a little soapy if you had a glass of it. The ocean is hidden beneath a layer of ice many miles thick, but frozen particles migrate through cracks in the ice and spurt into space. The plumes have sometimes been called “geysers,” but Postberg doesn’t like the term, as it suggests Old Faithful-like eruptions of liquid water.

The detection of phosphorus required years of analysis of data from particles impacting an instrument on Cassini as it hurled past the icy moon.

Phosphorus is the “P” in CHNOPS, which stands for carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur — the sextet of elements that, along with water and energy, are foundational to biochemistry on Earth. Because it is relatively rare, phosphorus has been considered a “bottleneck” for life, Postberg said.

But it’s abundant in the Enceladus ocean, according to Postberg and his colleagues. That means the soda ocean has no bottleneck. Phosphorus, the report states, is “thus extremely unlikely to be a limiting factor in the survival of putative life on Enceladus.”

Despite their great distance from the sun, the ice moons orbiting Jupiter and Saturn can host liquid oceans because they get energy from gravity. The small bodies are squeezed and stretched by tidal forces generated in their circuits around the huge planets, action that produces internal heat. Jupiter’s rocky moon Io, covered with volcanoes, is the star exhibit of that phenomenon. On Enceladus, tidal heating may be driving hydrothermal vents akin to the ones that spew nutrient-rich water into the ocean on Earth.

Biology remains a sufficiently embryonic science that a basic definition of “life” remains elusive. We have one sample to work with, Earth life, and although we can say with confidence what it requires, no one knows if this is a universal rule.

Earth life is constructed with common ingredients. It is not made of uranium, for example. But of the six essential elements, phosphorus plays an outsize role in terrestrial biochemistry. It’s necessary, for example, to the structure of DNA and RNA and for energy transfer in cells.

“Could there be an alternative biochemistry that doesn’t need to use P or uses something else? I suppose, but P as an element has the optimal properties to serve the roles that it does in life-as-we-know-it,” said Jonathan Lunine, a Cornell University planetary scientist who has studied ocean worlds and was not part of the new research.

Enceladus, he said in an email, “has such an earth-like interior ocean that if life is present, we will recognize it.”

Mikhail Zolotov is an Arizona State University planetary geochemist who served as a reviewer of the new paper and wrote a perspective article for Nature. He said he still favors Mars as the most likely abode of life beyond Earth. But he added that he is a scientist and not a science-fiction writer, and there are so many unknowns.

“We don’t know how life originated, and under what conditions,” he said.

Europa, one of Jupiter’s big moons, also might have the whole suite of CHNOPS elements. NASA’s Europa Clipper, a Jupiter orbiter scheduled for launch next year, will get a closer look. But for now, Enceladus is arguably the most fascinating world in our solar system — other than the one we’re standing on.