Jupiter's moon Europa may lack key ingredients for life after all

Jupiter's moon Europa is on the short list of places in our solar system seen as promising in the search for life beyond Earth, with a large subsurface ocean thought to be hidden under an outer shell of ice. But new research is raising questions about whether Europa in fact has what it takes for habitability.

The study assessed the potential on Europa's ocean bottom for tectonic and volcanic activity, which on Earth facilitate interactions between rock and seawater that generate essential nutrients and chemical energy for life. After modeling Europa's conditions, researchers concluded that its rocky seafloor is likely mechanically too strong to allow such activity.

They considered factors including Europa's size, the makeup of its rocky core and the gravitational forces exerted by Jupiter, the solar system's largest planet. Their evaluation that there probably is little to no active faulting at Europa's seafloor suggests this moon is barren of life.

"On Earth, tectonic activity such as fracturing and faulting exposes fresh rock to the environment where chemical reactions, principally involving water, generate chemicals such as methane that microbial life can use," said planetary scientist Paul Byrne of Washington University in St. Louis, lead author of the study published on Tuesday in the journal Nature Communications.

"Without such activity, those reactions are harder to establish and sustain, making Europa's seafloor a challenging environment for life," Byrne added.

Europa, with a diameter of roughly 3,100 km, about a quarter Earth's, is slightly smaller than our moon. Its icy shell is believed to be 15 km to 25 km thick, sitting atop an ocean perhaps 60 km to 150 km deep.

The fourth-largest of Jupiter's 95 formally recognized moons possesses three major ingredients thought to be critical for supporting life, with first and foremost liquid water. But its ocean of salty liquid water may contain double the water present in Earth's oceans.

The other two are organic chemicals spotted on its exterior icy shell and energy generated by tidal heating caused by the strong and varying gravitational pull of Jupiter. 

NASA in 2024 launched the robotic Europa Clipper spacecraft on a mission to examine whether Europa has conditions suitable to support life. The U.S. space agency is planning for Europa Clipper to conduct dozens of close flybys, starting in 2031.

Life may have emerged on Earth billions of years ago in the dynamic environment around seafloor hydrothermal vents. But Europa may lack these features.

"Based on our findings, the seafloor would probably not contain major tectonic landforms, such as long ridges or deep troughs. There would likely not be any underwater volcanoes or seamounts, and we would not have any hydrothermal activity such as black smokers. Having said that, I hope I will stand corrected one day," said University of Georgia geologist and study co-author Christian Klimczak.

"While geology operates similarly across the solar system, every planetary body that we have explored has been found to have some unique process to them. Given what we know about Europa, it is still the best place to look for extraterrestrial life," Klimczak said.

(With input from Reuters)