New simulations show that Saturn's moon Enceladus may harbor extraterrestrial life

A team of scientists, including Southwest Research Institute's Dr. Christopher Glein, discovered new evidence for a critical building block for life in the subsurface ocean of Saturn's moon Enceladus.

Glein is a globally recognized expert in extraterrestrial oceanography. According to a press release, He and his team's simulations show that the moon's ocean should have an abundance of dissolved phosphorus — an essential ingredient for life here on Earth.

Saturn moon habitability

"Enceladus is one of the prime targets in humanity's search for life in our solar system," Glein, co-author of a new paper on the subject, explained.

"In the years since NASA's Cassini spacecraft visited the Saturn system," he continued, "we have been repeatedly blown away by the discoveries made possible by the collected data."

The Cassini spacecraft discovered Enceladus's subsurface liquid water as it orbited Saturn. It was able to analyze samples as ice and water vapor erupted into space from cracks in the moon's icy surface. "What we have learned is that the plume contains almost all the basic requirements of life as we know it," Glein said. "While the bioessential element phosphorus has yet to be identified directly, our team discovered evidence for its availability in the ocean beneath the moon's icy crust."

Interior water worlds are much more common than worlds like Earth, where the ocean makes up much of the planet's surface. This is because planets like Earth must land in a narrow habitable zone away from their sun. On the other hand, interior water worlds hide their oceans between thick sheets of ice. But that doesn't mean microbial life can't reside in those oceans.

'We need to get back to Enceladus'

"The quest for extraterrestrial habitability in the solar system has shifted focus, as we now look for the building blocks for life, including organic molecules, ammonia, sulfur-bearing compounds as well as the chemical energy needed to support life," Glein explained. "Phosphorus presents an interesting case because previous work suggested that it might be scarce in the ocean of Enceladus, which would dim the prospects for life."

Phosphorus is required to create DNA and RNA, potentially a key indicator for life on other planets and moons. The Southwest Research Institute team members used insights from Cassini to carry out thermodynamic and kinetic modeling to simulate the geochemistry of phosphorus in the oceans of Enceladus. According to Glein, the models showed that "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. What this means for astrobiology is that we can be more confident than before that the ocean of Enceladus is habitable."

Those findings, Glein explained, make the next step very clear: "We need to get back to Enceladus to see if a habitable ocean is actually inhabited."