Does Europa support life? If so, this study might help explain why

Researchers at the University of Texas may have discovered a natural process on Europa that could, in theory, lay the foundations for supporting life on Jupiter's moon of frozen Europa. Originally published in the journal Geophysical Research Letters, according to their research, the icy shell of the moon could be transporting oxygen into the ice-covered liquid waters that would be a prerequisite for life as we know it living there. 

While not a new theory, this study offers some important support for it. To do this, the team developed the world's first physics-based computer model to simulate such a process that involves oxygen effectively hitching a ride on saltwater under the moon's so-called "chaos terrains" landscapes of cracks, ridges, and ice blocks that cover a quarter of the icy world.

The result of the simulation seems to indicate that such a mechanism is not only possible, but it could account for large-scale oxygenation of the moon's ocean comparable to levels in Earth's atmosphere. 

“Our research puts this process into the realm of the possible,” explained lead researcher Marc Hesse, a professor at the UT Jackson School of Geosciences Department of Geological Sciences. “It provides a solution to what is considered one of the outstanding problems of the habitability of the Europa subsurface ocean.”

The results of this model, if true, significantly improve the chances for life being supported on Europa

Europa is one of the best locations in our Solar System that may harbor life of its own other than Earth, as we have been able to detect oxygen and water on its surface. It also has a large number of other chemicals that are also vital for life. 

However, up to now, there has been a serious issue - the fact that its 9.32-mile-thick ice crust likely acts as a barrier between oxygen and water. If Europa does support life, it would likely need access to both of these vital substances. 

By Hesse's estimation, for this to happen, the most likely scenario is for oxygen to be carried by brine on the moon. 

To date, scientists believe that Europa's "chaos terrains" form above regions where Europa’s ice shell partially melts to form brine, which can mix with oxygen from the surface. Building on this, the computer model created by the researchers showed what happens to the brine after the formation of the "chaos terrain".

If correct, brine on Europa drains in a distinct pattern making what is called a "porosity wave" that causes pores in the ice to temporarily widen. This, in turn, allows the brine to pass through before the ice seals itself back up. Hesse compares the process to the classic cartoon gag of a bulge of water making its way down a garden hose.

If true, this would be a very effective and efficient means of bringing oxygen through the ice, with something like  86 percent of the oxygen taken up at the surface riding the wave all the way to the ocean. But the available data allows for a wide range of oxygen levels delivered to Europa’s ocean over its history – with estimates ranging by a factor of 10,000.

According to co-author Steven Vance, a research scientist at NASA’s Jet Propulsion Laboratory (JPL) and the supervisor of its Planetary Interiors and Geophysics Group, the highest estimate would make the oxygen levels in Europa’s ocean similar to those in Earth’s oceans. This would be very significant and significantly raises the chances of life, if it has evolved in Europa, to exist and thrive. 

“It’s enticing to think of some kind of aerobic organisms living just under the ice,” Vance said.

Vance also explained that NASA’s upcoming 2024 Europa Clipper mission may help improve estimates for oxygen and other ingredients for life on the icy moon.

Kevin Hand, a scientist focused on Europa research at NASA JPL who was not part of the study, said that the study presents a compelling explanation for oxygen transport on Europa.

“We know that Europa has useful compounds like oxygen on its surface, but do those make it down into the ocean below, where life can use them?” he said. “In the work by Hesse and his collaborators, the answer seems to be yes.”

Study Abstract: 

Researchers have built the world's first physics-based computer simulation of oxygen transport on Europa, finding that it's possible for oxygen to drain through the moon's icy shell and into its ocean of liquid water -- where it could potentially help sustain alien life -- by hitching a ride on saltwater under the moon's 'chaos terrains.' The results show that not only transports possible but that the amount of oxygen brought into Europa's ocean could be on par with the quantity of oxygen in Earth's oceans today.