Shallow lakes in Europa’s Icy Crust could erupt

Any plumes or volcanic activity at the Jovian moon’s surface are caused by shallow lakes in its icy crust.


Subsurface bodies of water in our outer solar system are some of the most crucial targets in the hunt for life beyond Earth. NASA is sending the Europa Clipper spacecraft to Jupiter’s moon Europa for the following reasons: There is compelling evidence that the moon is covered in a global ocean that may one-day support life.

Based on observations from NASA’s Galileo orbiter, they believe salty liquid reservoirs may reside inside the moon’s icy shell – some close to the surface of the ice and many miles below.

A new study has suggested that shallow lakes cause any plumes or volcanic activity at the Jovian moon’s surface in its icy crust. The findings support the longstanding idea that water could potentially erupt above the surface of Europa either as plumes of vapor or as cryovolcanic activity.

Further computer modeling in the research demonstrates that if Europa has eruptions, they are more likely to originate from shallow, wide lakes trapped in the ice rather than the deep ocean far below.

Elodie Lesage, Europa scientist at NASA’s Jet Propulsion Laboratory in Southern California and lead research author, said, “We demonstrated that plumes or cryolava flows could mean there are shallow liquid reservoirs below, which Europa Clipper would be able to detect. 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 to be detected by multiple Europa Clipper instruments.”

Lesage’s computer simulation offers a model for what scientists would discover if they looked inside the ice and saw explosions on the surface. The models predict that they would find reservoirs in the crust’s upper 2.5 to 5 miles (4 to 8 kilometers), where the ice is the coldest and most brittle, quite close to the surface.

That’s because the subsurface ice there doesn’t allow for expansion: As the pockets of water freeze and expand, they could break the surrounding ice, and trigger eruptions, much like a can of soda in a freezer explodes. And pockets of water that burst through would likely be wide and flat like pancakes.

Deeper reservoirs, with floors greater than 5 miles (8 kilometers) below the crust, would expand and push on warmer ice around them. That ice is so soft to act as a cushion, absorbing the pressure instead of bursting. These pockets of water wouldn’t behave like a can of soda but more like a balloon packed with liquid that stretches as the liquid inside freezes and expands.

Don Blankenship of the University of Texas Institute for Geophysics in Austin, Texas, who leads the radar instrument team, said, “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. That means REASON could be able to see water bodies in the same places that you see plumes.”

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 make high-resolution color and stereoscopic images of Europa; the thermal emission imager will use an infrared camera to map Europa’s temperatures and find clues about geologic activity – including cryovolcanism. If plumes erupt, they could be observable by the ultraviolet spectrograph, the instrument that analyzes ultraviolet light.

Journal Reference:

  1. Elodie Lesage, Helene Massol, et al. Simulation of Freezing Cryomagma Reservoirs in Viscoelastic Ice Shells. The Planetary Science Journal. DOI: 10.3847/PSJ/ac75bf
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