Saturn’s moon harbors essential element for life – 06/15/2023 – Science

High concentrations of phosphorus, an essential element for all biological processes on Earth, have been detected in ice crystals expelled from the ocean of Saturn’s moon Enceladus, increasing its potential to harbor life, researchers reported Wednesday.

The discovery was based on data collected by NASA’s Cassini spacecraft, the first to orbit Saturn, during its historic 13-year exploration of the gas giant planet, its rings and its moons, from 2004 to 2017.

The findings were published by a German-led international team of scientists in the journal Nature and announced by NASA’s Jet Propulsion Laboratory (JPL) near Los Angeles, which designed and built the Cassini spacecraft.

The same team previously confirmed that Enceladus’ ice grains contain a rich variety of minerals and complex organic compounds, including ingredients for amino acids, associated with life as scientists know it.

But phosphorus, the least abundant of the six chemical elements considered necessary for all living beings —the others are carbon, oxygen, hydrogen, nitrogen and sulfur—, was still missing from the equation.

“It’s the first time that this essential element has been discovered in an ocean beyond Earth,” lead study author Frank Postberg, a planetary scientist at the Free University of Berlin, said in a JPL press release.

Phosphorus is fundamental to the structure of DNA and a vital part of cell membranes and energy-carrying molecules found in all forms of life on Earth.

The latest study stems from measurements taken by Cassini as it flew through salt-rich ice grains ejected into space by geysers erupting from the ocean below Enceladus’ frozen crust at its south pole.

The spacecraft collected its data during passes through a plume of ice crystals and the same material that feeds ice particles to Saturn’s faint “E” ring outside the planet’s brightest main rings.

The interior ocean discovered by Cassini made Enceladus — about one-seventh the size of Earth’s moon and the sixth-largest of Saturn’s 146 known natural satellites — an excellent candidate for looking for places in our solar system beyond Earth. that are habitable, if only for microbes.

Another is Jupiter’s largest moon Europa, which also harbors a global ocean of liquid water beneath its icy surface.

A notable aspect of the latest Enceladus discovery was the geochemical modeling by study co-authors in Europe and Japan, showing that phosphorus exists in concentrations at least a hundred times greater than those in Earth’s oceans, bound to water-soluble forms of phosphate compounds. water.

“This key ingredient could be abundant enough to potentially support life in the ocean of Enceladus,” said lead investigator Christopher Glein, a planetary scientist at the Southwest Research Institute in San Antonio, Texas. “This is an impressive discovery for astrobiology.”

Still, the scientists emphasized that the presence of phosphorus, complex organic compounds, water and other fundamental building blocks of life are just evidence that a place like Enceladus is potentially habitable, not that it is inhabited. Life, past or present, has not been confirmed anywhere other than Earth.

“Whether life could have arisen in Enceladus’ ocean remains an open question,” said Glein.

^{Translated by Luiz Roberto M. Gonçalves}