SwRI Lead Scientist Dr. Christopher Glein contributed to new findings that phosphorus in the form of orthophosphate (e.g. HPO42-) is likely abundant in the subsurface ocean of Saturn’s moon Enceladus. A soda or alkaline sea (containing NaHCO3 and/or Na2CO3) interior of Enceladus interacts geochemically with a rocky core. Modeling indicates that this interaction promotes the dissolution of phosphate minerals, making orthophosphate readily available to possible marine life. Because phosphorus is an essential ingredient for life, this discovery strengthens the growing evidence for habitability in this small Saturnian moon. Credit: Southwest Research Institute
The hunt for extraterrestrial life just got more interesting as a team of scientists, including Southwest Research Institute’s Dr. Christopher Glein, has discovered new evidence for a key building block for life in the subsurface ocean of Saturn’s moon Enceladus. New modeling indicates that Enceladus’ ocean should be relatively rich in dissolved phosphorus, an essential ingredient for life.
“Enceladus is one of the main targets in humanity’s search for life in our solar system,” said Glein, a leading expert on extraterrestrial oceanography. He is co-author of an article in Proceedings of the National Academy of Sciences which describes this research. “In the years since NASA’s Cassini spacecraft visited the Saturn system, we have repeatedly been blown away by the discoveries made possible by the data collected.”
The Cassini spacecraft detected Enceladus’ subsurface liquid water and analyzed samples as plumes of ice grains and water vapor erupted into space from cracks in the moon’s icy surface.
“What we’ve learned is that the feather contains almost all of the basic requirements for life as we know it,” Glein said. “While the bioessential element phosphorus has yet to be directly identified, our team discovered evidence of its availability in the ocean beneath the moon’s icy crust.”
One of the most profound discoveries in planetary science in the past 25 years is that worlds with oceans beneath a surface layer of ice are common in our solar system. Such worlds include the icy satellites of the giant planets, such as Europa, Titan and Enceladus, as well as more distant bodies such as Pluto. Worlds like Earth with surface oceans must lie within a narrow range of distances from their host stars to maintain temperatures that support liquid surface water. However, inland ocean worlds can occur over a much wider range of distances, increasing the number of habitable worlds likely to exist throughout the galaxy.
“The search for extraterrestrial habitability in the solar system has shifted focus, as we now look for the building blocks of life, including organic molecules, ammonia, sulfur-containing compounds as well as the chemical energy needed to support life,” Glein said. “Phosphorus presents an interesting case because previous work suggested that it may be low in Enceladus’ ocean, which would dampen the prospects for life.”
Phosphorus in the form of phosphates is vital for all life on earth. It is essential for the formation of DNA and RNA, energy-carrying molecules, cell membranes, bones and teeth in humans and animals, and even the ocean’s microbiome of plankton.
Team members performed thermodynamic and kinetic modeling that simulates the geochemistry of phosphorus based on insights from Cassini about the ocean-ocean floor system on Enceladus. In the course of their research, they developed the most detailed geochemical model to date of how seafloor minerals dissolve in Enceladus’ oceans and predicted that phosphate minerals would be unusually soluble there.
“The underlying geochemistry has an elegant simplicity that makes the presence of dissolved phosphorus inevitable, reaching levels close to or even higher than those in modern Earth seawater,” Glein said. “What this means for astrobiology is that we can be more certain than before that the ocean of Enceladus is habitable.”
According to Glein, the next step is clear: “We need to return to Enceladus to see if a habitable ocean is actually inhabited.”
Theoretical model suggests that the salinity of Enceladus’ oceans may be just right to sustain life
“Abundant Phosphorus Expected for Possible Life in Enceladus’ Ocean”, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2201388119
Provided by Southwest Research Institute
Citation: Scientist helps identify new evidence for habitability in ocean of Saturn’s moon Enceladus (2022, September 19) Retrieved September 20, 2022, from https://phys.org/news/2022-09-evidence-habitability-ocean- saturn-moon.html
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