Enceladus, Saturn’s icy moon, is home to life’s essentials

By Steve Gorman

(Reuters) – High concentrations of phosphorus, an essential element for all biological processes on Earth, have been detected in ice crystals spewed from the inner ocean of Saturn’s moon Enceladus, adding to its potential to harbor the 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 in 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) outside Los Angeles, which designed and built the Cassini probe.

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

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

“This is the first time that this essential element has been discovered in an ocean beyond Earth,” study lead author Frank Postberg, a planetary scientist at the Free University of Berlin, said in a statement. 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 life forms on Earth.

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

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

The inner ocean discovered by Cassini has made Enceladus – about a seventh the size of Earth’s moon and the sixth largest of Saturn’s 146 known natural satellites – a prime candidate in finding places in our system. solar beyond the Earth that are habitable, if only to microbes.

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

A notable aspect of the latest Enceladus discovery was geochemical modeling by the study’s co-authors in Europe and Japan, showing that phosphorus exists in concentrations at least 100 times greater than those in Earth’s oceans. , bound to water-soluble forms of phosphate compounds.

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

Yet scientists have pointed out that the presence of phosphorus, complex organic compounds, water, and other basic building blocks of life are just proof that a place like Enceladus is potentially habitable, not inhabited. Life, past or present, has not been confirmed anywhere beyond Earth.

“Whether life could have originated in the ocean of Enceladus remains an open question,” Glein said.

(Reporting by Steve Gorman in Los Angeles; Editing by Lisa Shumaker)

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