For the first time, phosphates have been discovered in exotic surroundings. This discovery was found on Saturn’s moon Enceladus, and raises the possibility of life existing on the small, frozen satellite.
The phosphorus-containing compounds in the vapor emitted from Saturn’s moon Enceladus – the solar system body with the largest proportion of liquid water by mass – have been identified by an international team led by planetary scientist Frank Postberg of the Free University of Berlin in Germany. The quantities found indicate that there may be abundances 100 times higher than what we have here on Earth.
This means we have new evidence for understanding ocean worlds in the solar system and beyond. And since phosphorus is one of the six elements considered critical to life based on water and organic chemistry, its discovery greatly raises the prospects for life on Enceladus.
“Phosphorus is an essential element for planet habitation, but so far, it has not been detected in an ocean beyond Earth. Previous geochemical modeling has suggested that phosphate may be scarce in the vicinity of Enceladus and other icy ocean worlds,” the researchers write in their paper.
“In this work, we provide CDA mass spectra of a group of E-ring ice grains that show the presence of sodium phosphate. We then perform corresponding laboratory experiments to quantitatively demonstrate that Enceladus’ ocean is rich in dissolved phosphate.”
At one-seventh the size of Earth’s moon, Enceladus might not seem like much at first glance, but a lot is going on beneath its frigid outer surface. When the Saturn probe Cassini first detected hot springs erupting from Enceladus, it revealed the existence of a global ocean, which retains liquid due to heat generated by the constant pushing of clouds. the moonGravitational interaction with Saturn.
Saturn, and by extension, Enceladus, are far from the life-nurturing warmth of the Sun, upon which the vast majority of Earth’s food webs depend. But here on Earth, in the very dark and cold regions of the deep sea where sunlight hardly penetrates, chemistry-dependent food webs thrive around heat vents on the ocean floor.
That could also be the case for Enceladus, but it’s not like we can just hop on and send a submarine under it at least 20 km (12 miles) Ice crust to peek a little.
Fortunately, Enceladus is a messy monster. These heaters are an active and continuous feature; In fact, they create and maintain Saturn’s outer E ring, a hazy ring of material made up mostly of microscopic particles of water ice, where Enceladus is comfortably hiding.
And Cassini, before its dramatic final death in Saturn’s clouds at the end of 2017, sampled that ring, collecting the shimmering light from the ice.
In the intricacies of this light, details about chemistry can be discerned. Elements and compounds absorb certain wavelengths and re-emit them at others; By dividing the light into rainbows and looking for bright and dim sections, scientists can identify which chemicals are present, much like a chemical fingerprint.
Postberg and his colleagues did this, taking data from Cassini’s Cosmic Dust Analyzer instrument and performing a comprehensive analysis of 345 particles. In nine of these particles, they identified spectral features that they found to be unique to sodium phosphate — a compound of sodium and phosphorus.
Next, they ran an experiment to try to replicate the spectrum, shooting a laser at a beam of water in which sodium orthophosphate and dihydrogen phosphate had been dissolved. They were able to reproduce the chemical signature they found in the ice grains in the E ring. The abundance of these elements required to reproduce the spectrum indicates a high abundance of sodium in the vicinity of Enceladus.
“The CDA’s detection of ice grains with high concentrations of phosphate indicates that phosphorus is readily available in the upper part of Enceladus’ ocean (i.e. the plume source region),” write the researchers. “Even with a conservative margin, our estimate indicates concentrations in the order of at least hundreds of micromolar, and several times the average phosphate abundance in Earth’s oceans.”
So where does phosphorus come from? Enceladus lies beneath its dirty, liquid ocean It is believed to have a core composed From a type of rock called chondrosarcomas. The team conducted experiments in this direction and found that phosphorus is an inevitable product of the reaction between alkaline and carbonate-rich ocean waters and this rock.
So not only is phosphorus likely abundant on Enceladus, but there is also a plausible source for it.
The other five of the six elements of interest — carbon, hydrogen, nitrogen, oxygen, and sulfur — have already been identified in emissions from Enceladus, although the detection of sulfur is tentative.
So can we go there? Pleeeeeaaaase?
The team’s research is published in nature.
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