Beneath Jupiter’s icy moon Europa’s icy crust lies a deep ocean that could be habitable. But scientists now believe there is another type of water reservoir on the distant moon: lakes within the crust. These bodies of water may be responsible for eruptions occurring on the surface of this frozen world.
New computer simulations have looked at how the huge lakes are likely to squeeze the ice around them as their temperature changes. Water ice is less dense than liquid water, so if one of these lakes begins to freeze, its volume will expand, putting pressure on the surrounding walls.
For some of these lakes, the pressure will be too much and cracks in the surface will have water gushing out. This can happen either as clouds of vapor spreading out into space or as cryovolcanoes, eruptions of slushy, salty ice rather than the hot volcanoes we have on Earth and its fellow Jovian moon Io.
“We showed that cryolava plumes or flows could mean that there are shallow reservoirs of liquid below that the Europa Clipper could detect,” lead study author Elodie Lesage, a Europa scientist at NASA’s Jet Propulsion Laboratory, said in a statement. .
“Our results give new insights into how deep the water driving surface activity, including plumes, can be. And the water would have to be shallow enough to be detected by multiple Europa Clipper instruments.”
This image depicts a plume of water vapor that could potentially be emitted from the icy surface of Jupiter’s moon Europa. Image credit: NASA/ESA/K. Retherford/SWRI
The Europa Clipper is NASA’s mission that will launch in 2024 to study this icy moon. The presence of these possible lakes will hopefully be confirmed by the instrument outfit on the spacecraft. For example, the Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON) is designed to study the frozen crust.
The model suggests that these reservoirs may exist very close to the surface, perhaps 4 to 8 kilometers (2.5 to five miles) deep. The crust is expected to be 15 to 25 kilometers (10 to 15 mi) thick.
“The new work shows that bodies of water in the shallow subsurface could be unstable if stresses exceed ice strength and could be associated with plumes rising above the surface,” added Don Blankenship, of the University’s Institute of Geophysics of Texas in Austin. Texas, who leads the radar instrument group. “That means REASON could see bodies of water in the same places you see plumes.”
The work is published in the Planetary Science Journal.