NASA Study Suggests Shallow Lakes Could Erupt in Europe’s Ice Crust – Astrobiology

New research raises hypotheses for NASA’s Europa Clipper to test: Any plumes or volcanic activity on Jupiter’s moon’s surface are caused by shallow seas in its icy crust.

Subterranean waters in our outer solar system are among the most important targets in the search for life beyond Earth. This is why NASA is sending the Europa Clipper spacecraft to Jupiter’s moon Europa: There is strong evidence that the moon hosts a global ocean beneath a thick crust of ice that could potentially be habitable.

However, scientists believe that the ocean is not the only water on Europa. Based on observations from NASA’s Galileo orbiter, they believe there may be reservoirs of saline liquid in the moon’s icy shell — some close to the ice surface and some many miles below.

The more scientists understand about the water Europa may contain, the more likely they will know where to look for it when NASA sends Europa Clippers to conduct a detailed survey in 2024. The spacecraft will orbit Jupiter and use its sophisticated instruments to collect scientific data as it flies by the moon about 50 times.

Now the research is helping scientists better understand what Europe’s underground lakes look like and how they behave. A key finding in a recent article published in the Planetary Science Journal supports the long-standing idea that water could potentially erupt over Europa’s surface as either vapor clouds or cryovolcanic activity (think: flowing, squishy ice rather than molten lava).

The computer modeling in the publication goes even further, showing that if there are outbursts on Europa, they are likely to come from shallow, wide lakes embedded in the ice rather than from the global ocean far below.
“We showed that plumes or cryolava flows could mean there were shallow reservoirs of liquid underneath that Europa Clipper could detect,” said Elodie Lesage, a Europa scientist at NASA’s Jet Propulsion Laboratory in Southern California and lead author of the research. “Our results provide new insights into how deep the water might be that drives surface activity, including plumes. And the water should be shallow enough for multiple Europa Clipper instruments to pick it up.”

Different depths, different ice

Lesage’s computer modeling provides a blueprint for what scientists might find in the ice if they observed surface eruptions. According to their models, they would likely detect reservoirs relatively close to the surface in the top 2.5 to 5 miles (4 to 8 kilometers) of the crust, where the ice is coldest and most brittle.

That’s because the subsurface ice doesn’t allow for expansion there: if the pockets of water freeze and expand, they could fracture the surrounding ice and trigger eruptions, much like a can of soda explodes in a freezer. And pockets of water that break through would likely be as wide and flat as pancakes.
Reservoirs deeper in the ice sheet — with bottoms more than 5 miles (8 kilometers) below the crust — would push against warmer ice surrounding them as they expand. This ice is soft enough to act as a cushion and absorb pressure rather than bursting. Instead of acting like a soda can, these water bags would behave more like a balloon filled with liquid, where the balloon simply expands as the liquid it contains freezes and expands.

Feel firsthand

Scientists on the Europa Clipper mission can use this research when the spacecraft arrives in Europe in 2030. For example, the radar instrument – called Radar for Europa Assessment and Sounding: Ocean to Near-Surface (REASON) – is one of the key instruments used to look for water pockets in ice.

“The new work shows that shallow subsurface water bodies could be unstable when stresses exceed the strength of the ice and could be associated with clouds rising above the surface,” said Don Blankenship of the University of Texas Department of Geophysics in austin Texas, who leads the radar instrument team. “That means REASON might be able to see bodies of water in the same places you see feathers.”
Europa Clipper will carry other instruments that will be able to test the theories of the new research. The science cameras will be able to take high-resolution color and stereo images of Europe; The Thermal Emission Imager will use an infrared camera to map Europe’s temperatures and find evidence of geological activity – including cryovolcanism. When feathers erupt, they could be observed by the ultraviolet spectrograph, the instrument that analyzes ultraviolet light.

More about the mission

Missions like Europa Clipper contribute to the field of astrobiology, the interdisciplinary field of research that studies the conditions of distant worlds that could host life as we know it. While Europa Clipper is not a life detection mission, it will conduct a detailed exploration of Europa and investigate whether the icy moon with its subterranean ocean has the ability to support life. Understanding Europa’s habitability will help scientists better understand how life evolved on Earth and the potential to find life outside of our planet.

Led by Caltech in Pasadena, California, JPL is leading the development of the Europa Clipper mission in partnership with APL for NASA’s Science Mission Directorate in Washington. APL designed the main body of the spacecraft in collaboration with JPL and NASA’s Goddard Space Flight Center in Greenbelt, Maryland. The Planetary Missions Program Office at NASA’s Marshall Space Flight Center in Huntsville, Alabama conducts program management of the Europa Clipper mission.

For more information on Europa, go to europa.nasa.gov

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