According to new research, phosphorous, a crucial element for life as we know it, may be abundant in the water of Saturn’s moon Enceladus.
A crucial element of the biochemistry of life is phosphorus. For instance, it works with sugars to give DNA a “backbone” that connects the double helix’s four nucleobases. In addition to being employed in bones and cell membranes, phosphorus is also a component of the molecule adenosine triphosphate, which transports metabolic energy throughout the body.
However, earlier research had indicated that phosphorous would be scarce on Enceladus. Huge water geysers that shoot out of “tiger stripes,” or deep fractures in the moon’s frozen surface, allowed scientists to see a peek of the composition of the ocean. Before its mission concluded in 2017, NASA’s Cassini spacecraft sailed through and “tasted” these geysers, examining the chemical compositions on several times. A number of chemicals and components essential to life as we know it were found by the spacecraft, including organic compounds like methane, ammonia, carbon, nitrogen, oxygen, and perhaps hydrogen sulphide.
But it is notable that there is no phosphorous. Phosphorus would be limited in Enceladus’ ocean, according to research conducted in 2018 by Harvard’s Manasvi Lingam and Avi Loeb. This is because the phosphorus in the rocks on the seafloor would progressively dissolve into the water. On Earth, the weathering of dry soil produces phosphorus, which Enceladus does not.
The 2018 research, according to a recent study led by Jihua Hao, a senior research scientist at the University of Science and Technology of China, employed out-of-date geochemical models of Enceladus’ rocky ocean floor, contradicting the earlier findings.
Although the bio-essential element phosphorus has not yet been directly identified, study co-author Christopher Glein, a senior research scientist at the Southwest Research Institute in San Antonio, said in a statement that his team had found evidence for its availability in the ocean beneath the moon’s icy crust.
Hao and Glein’s team simulated how phosphorus-rich minerals called phosphates dissolve into the ocean from Enceladus’ rocky core using novel models based on the most recent data. The scientists discovered that the rate of disintegration of a mineral called orthophosphate would be significantly faster than what earlier analyses predicted, and that it could fill the ocean with a concentration high enough to support life in just tens of thousands of years. The existence of bicarbonates in the ocean water, whose chemical properties allow phosphates to accumulate in the ocean, is one factor making this high concentration possible.
The occurrence of dissolved phosphorus, which can reach concentrations that are comparable to or even higher than those seen in present seawater [on Earth], is unavoidable due to the beautiful simplicity of the underlying geochemistry, according to Glein. We can now be more certain than ever that the ocean on Enceladus is habitable, which is good news for astrobiology.
A future trip to Enceladus would need to directly locate orthophosphate or another phosphorus-derived mineral in the water geysers that frequently erupt from the moon in order to verify that the ocean there includes phosphorus, despite the exciting possibilities.
To determine whether a habitable ocean is genuinely inhabited, Glein remarked, “We need to return to Enceladus.”