NASA’s Cassini spacecraft found no evidence of a key ingredient for life in the giant space geysers that erupt from Enceladus at the time, but new research by planetary scientist Jihua Hao (University of Science and Technology) China Technology) and colleagues, argues that their computer models of the icy moon’s geology and chemistry suggest that (life) could be there anyway.
“Enceladus is one of the main targets in humanity’s search for life in our solar system. In the years since NASA’s Cassini spacecraft visited the Saturn system, we have been repeatedly amazed by discoveries that have been possible thanks to the collected data “, explains Christopher R. Glein, co-author of the work published in the journal Proceedings of the National Academy of Sciences.
New geochemical model of Enceladus
The Cassini spacecraft discovered 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.
Scientists at the Southwest Research Institute decided to find out if it could be that the phosphorus in the Enceladus samples just wasn’t showing up. They collected all the data on the chemical composition of the satellite’s water collected by Cassini, combined it with models of the planet’s internal structure, and reproduced the thermodynamic and kinetic situation in its ocean.
They built a model of how streams of various substances should move and interact with each other. They concluded that the phosphorus on Enceladus should still be in the form of orthophosphates, which dissolve easily in water and are often used on Earth as acidity regulators in beverages. Thus phosphorus in the planet’s rocky core would leach into the water above it (and flow through it if the rock is porous in places).
“What this means for astrobiology is that we can be more certain than before that Enceladus’ ocean is habitable ,” added Glein.
The experts comment that “while the bioessential element phosphorus has not yet been directly identified, our team discovered evidence of its availability in the ocean beneath the moon’s icy crust.” And so far, scientists haven’t found any signs of phosphorus in the data NASA’s Cassini spacecraft collected when it swooped into the plumes of Enceladus in 2017.
Several years after Cassini’s dramatic end, scientists are still studying the data the spacecraft sent back to Earth.
As scientists and astronomers continue to study ocean worlds like Enceladus and Jupiter’s moon Europa from afar, Glein cites another important step that needs to be taken as soon as possible: “We need to go back to Enceladus to see if a habitable ocean is actually inhabited.”
Phosphorus rarely appears on its own; most of the time, it binds with oxygen molecules to form a chemical compound called phosphate. But finding other phosphorus compounds, combinations of phosphorus and other elements, could suggest not just a habitable environment, but real life on Enceladus.
It’s time to send a new and future mission to Enceladus.
“The search for extraterrestrial habitability in the solar system has shifted focus, as we now search for the building blocks for life, including organic molecules, ammonia, sulfur-containing compounds, and the chemical energy needed to support life,” Glenn said. “Phosphorus presents an interesting case because previous work suggested it might be scarce in Enceladus’ ocean, dimming the prospects for life.”
Referencia: Jihua Hao, Christopher R. Glein, Fang Huang, Nathan Yee, David C. Catling, Frank Postberg, Jon K. Hillier, Robert M. Hazen. Abundant phosphorus expected for possible life in Enceladus’s ocean. Proceedings of the National Academy of Sciences, 2022; 119 (39) DOI: 10.1073/pnas.2201388119
