Europa’s Ocean Floor May Be Too Still for Life

For decades, scientists have imagined Europa’s hidden ocean as a place where alien microbes might thrive around volcanic vents, much like they do in Earth’s deepest seas. That vision is now facing a reckoning. A new study suggests the seafloor beneath Jupiter’s icy moon is probably locked tight, with no active fractures, no fresh volcanic heat, and no way to refresh the chemical fuel that life would need.

The research, led by planetary scientist Paul Byrne at Washington University in St. Louis, concludes that the forces acting on Europa today are simply too weak to crack its rocky interior. Without that geologic activity, the ocean may have settled into a kind of chemical stalemate, where the water and rock have nothing left to trade. On Earth, tectonic plates constantly expose fresh minerals to seawater, creating the energy gradients that deep-sea organisms depend on. Europa appears to lack that engine entirely.

The team modeled stresses from Jupiter’s gravity, the moon’s internal cooling, and its sluggish mantle convection. Even accounting for tidal flexing every 84 hours, the numbers came up short. The diurnal tide contributes only about three percent of the stress needed to reactivate old faults. For the seafloor to crack under its own weight, Europa would need to have shrunk by at least one kilometer in radius. There is no evidence that has happened recently.

“If we could explore that ocean with a remote-control submarine, we predict we wouldn’t see any new fractures, active volcanoes, or plumes of hot water on the seafloor,” Byrne explains.

Not Enough Stress to Break Rock

The researchers took a deliberately conservative approach, assuming Europa’s seafloor was already weakened by earlier tectonic episodes. Even with that head start, the forces at work today fall far short of what is needed to fracture rock at the boundary between brittle and ductile layers. The stress from mantle convection, for instance, registers around 150 kilopascals, while breaking the rock would require upward of 51 megapascals. That gap spans more than two orders of magnitude.

Europa’s mantle is also unusually small, roughly half the volume of Mars. That limits how vigorously it can churn, further reducing the likelihood of active geology. Without movement in the mantle or contraction of the moon’s interior, the seafloor remains under crushing pressure from the overlying ocean and ice, effectively frozen in place.

What This Means for the Search

A geologically dead seafloor does not necessarily mean a lifeless ocean, but it does change where scientists might look for energy. If microbial life exists in Europa’s water, it probably cannot rely on the kind of hydrothermal circulation that powers ecosystems around Earth’s mid-ocean ridges. Instead, any organisms would need to tap into slower processes, such as radiolysis, where radioactive decay splits water molecules into hydrogen and oxygen.

The real answers will come in 2031, when NASA’s Europa Clipper arrives in orbit around Jupiter. The spacecraft will not land or drill through the ice, but it will map the moon’s gravity field and surface features in enough detail to reveal what is happening beneath. Those measurements could confirm whether the seafloor is as static as the models suggest or whether some geologic surprise is still waiting in the dark.

Byrne remains philosophical about the possibility of disappointment. Life may exist elsewhere in the solar system or beyond, even if Europa turns out to be a cold archive rather than a living world. Understanding why one ocean fails to support life could be just as valuable as finding one that does.

Nature Communications: 10.1038/s41467-025-67151-3