Aliens on Enceladus: Microbes Thrive in Environment Similar to Saturn's Icy Moon

Saturn's icy moon Enceladus, as pictured by NASA's Cassini spacecraft. NASA/JPL-Caltech/Space Science Institute

Microbes could be pumping methane into the erupting gas plumes of Enceladus, one of Saturn's moons, a new laboratory simulation has shown.

Microorganisms producing the gas thrived in a laboratory environment that was designed to mimic conditions on the moon. Furthermore, researchers think there may be enough molecular hydrogen on Enceladus to support this life.

Earth-like hydrothermal activity

Enceladus is a "hot spot" in the search for extraterrestrial life, the authors wrote in the study published this week in Nature Communications.

Geophysical evidence suggests a liquid ocean and a rocky core lie beneath the moon's icy shell. Hydrothermal activity sends plumes of water and gas through cracks in Enceladus's frozen surface. Before it plunged to its death, NASA's Cassini probe found gases including methane, carbon dioxide and molecular hydrogen in these jets.

"There are many conditions on Enceladus that are similar to environments...found on Earth. On Earth, these environments (anaerobic, hydrothermal vent systems) harbor life," study author Simon Rittmann from the University of Vienna told Newsweek in an email interview. "We tried to reproduce the putative Enceladus-like conditions in the lab and to grow methanogens under these conditions."

Methanogens are microorganisms which can produce methane. Their presence on Enceladus could—theoretically—account for some of the methane detected in the moon's plumes.

The team investigated different gas and pressure compositions which could mimic those of Enceladus. Then they cultivated methanogens—some of which grew even in the presence of potential inhibitors like formaldehyde.

Microbes munch on molecular hydrogen

The microbes consume carbon dioxide and molecular hydrogen for growth, churning out methane in the process.

A process called serpentinization can alter rock in hydrothermal systems on Earth, and scientists think something similar might be happening in the rocky heart of Enceladus. These geochemical reactions, the researchers think, might produce enough molecular hydrogen to support these microorganisms.

Theoretically possible

Unfortunately for alien hunters, this study cannot actually confirm what is happening on Enceladus. But, this simulation offers a window into the distant icy moon. "The conditions of the lab experiments could not encompass all putative conditions...on Enceladus. But, we tried to be as broad as possible with the experiments," Rittmann said.

While it doesn't prove microbes exist on Enceladus, it does show they might be possible. "Some of the [methane] detected in the plume of Enceladus might, in principle, be produced by methanogens," the authors wrote in the study.

However, the research had its limitations. Methane, for example, can be produced via non-biological means. The authors modeled this kind of methane production rate as part of their work, but suggest efforts to find chemical signatures of biological methane production would be valuable.

The next steps for the team will take them back down to their home planet. They will investigate how methanogens grow in serpentinization environments on Earth, Rittmann told Newsweek.