Jupiter's moon Europa could support alien life, scientists announce after finding activity under its shell

A moon in our own solar system might support life, according to scientists.

Europa, which orbits around Jupiter, looks cold and desolate. But strange activity appears to be happening under its surface – which could indicate that it would be hospitable to aliens, according to scientists who study it.

Researchers say they have found evidence that there are sliding tectonic plates underneath the moon's ice shell. The presence of such activity could have important implications for the possibility of life in the sea that scientists think is hiding underneath the crust that covers it.

That crust appears to contain within it oxidants and other chemical food that can support life. If the tectonic plates are moving, then they could cause a process called subduction – where those materials would be spread into the sea beneath and provide the material for whatever alien life lurks beneath.

"If indeed there's life in that ocean, subduction offers a way to supply the nutrients it would need," said Brandon Johnson, an assistant professor in Brown's Department of Earth, Environmental and Planetary Sciences and a lead author of the study.

On Earth, that process of subduction happens when slabs are pushed into the hot mantle – since the cooler material from the crust is more dense, it sinks down deep into the mantle and causes movement within the planet. But it wasn't clear how that would work on an icy planet, without such differences in temperature.

But the new research found the same thing might happen with the amount of salt, rather than heat. That would change the density of the slabs and move them around.

"Adding salt to an ice slab would be like adding little weights to it because salt is denser than ice," said Professor Johnson. "So rather than temperature, we show that differences in the salt content of the ice could enable subduction to happen on Europa."

The movements have important implications for life on Europa. But they're also incredibly important in themselves – they would be the first time that we've somewhere else that has such movements like us, and so give us the opportunity to compare them as never before.

""It's fascinating to think that we might have plate tectonics somewhere other than Earth," said Professor Johnson. "Thinking from the standpoint of comparative planetology, if we can now study plate tectonics in this very different place, it might be able to help us understand how plate tectonics got started on the Earth."

It's somewhere between unlikely and basically impossible that there's live on any of the large planets in our solar system. Mars is the most likely home for aliens – and it's almost certain that if anything did once live there, it's not dead.

But other smaller worlds – like icy Europa and Saturn's similar moon Enceladus – seem more promising. They appear to have plenty of water and other important materials, and scientists have even detected processes on them that would suggest they could actually support some forms of alien life.