NASA scientists believe large lakes could be hiding within Europa's icy shell

Jupiter's icy moon Europa is one of the most intriguing targets in the search for potentially habitable regions of our Solar System.

NASA's Juno spacecraft recently performed a flyby of the moon, and the space agency's Europa Clipper spacecraft will soon launch on a mission specifically designed to investigate Jupiter's celestial neighbor.

The reason behind this is the fact that strong evidence suggests there is a massive ocean beneath Europa's thick, icy crust that could potentially be habitable. Now, scientists have theorized that there are also large pockets of water hidden within that ice shell, a blog post from NASA reveals.

Europa's icy shell might be hiding large water reservoirs

Scientists believe salty liquid reservoirs may reside within Europa's icy shell — some of them close to the surface and others far below. The new discovery is detailed in a paper published in The Planetary Science Journal.

The discovery was made thanks to observations taken by NASA's Galileo orbiter that may help guide NASA's Europa Clipper mission, which is set to launch in 2024.

The Galileo orbiter's observations support the long-held idea that water could erupt above the surface of Europa as plumes of vapor or as cryovolcanic activity — the latter would resemble a volcanic eruption but with slushy ice instead of lava.

NASA scientists used computer simulations to show that any eruptions would likely come from these liquid reservoirs instead of from the ocean deep below the icy surface.

"We demonstrated that plumes or cryolava flows could mean there are shallow liquid reservoirs below, which Europa Clipper would be able to detect," explained Elodie Lesage, Europa scientist at NASA's Jet Propulsion Laboratory in Southern California and lead author of the research. "Our results give new insights into how deep the water might be that's driving surface activity, including plumes. And the water should be shallow enough that it can be detected by multiple Europa Clipper instruments."

The scientists' computer models suggest water reservoirs on Europa would be located somewhere in the upper 2.5 to 5 miles (4 to 8 kilometers) of the crust, where the ice layer is at its most brittle and at the lowest temperature. As that brittle subsurface ice doesn't allow for expansion, freezing pockets of water could break the surrounding ice, leading to massive eruptions.

Europa Clipper will shed new light on Jupiter's icy moon

Once it arrives at Jupiter in 2030, the Europa Clipper spacecraft will fly by Europa about 50 times as it orbits the gas giant. New insights from studies like this one can help to guide the work of NASA scientists controlling that mission. They can use the spacecraft's radar instrument, called Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON), for example, to search for pockets of ice at the depths described by the study.

"The new work shows that water bodies in the shallow subsurface could be unstable if stresses exceed the strength of the ice and could be associated with plumes rising above the surface," explained Don Blankenship of the University of Texas Institute for Geophysics in Austin, Texas, who leads the radar instrument team. "That means REASON could be able to see water bodies in the same places that you see plumes."