NASA finds giant frozen lake beneath Europa

Has any taken a look at the Great Lakes lately? Lake Michigan, Lake Huron, Lake Ontario, Lake Something Else, etc. Are they still there? Phew.

It must be some other water entirely, then, that NASA scientists have just discovered lurking like a frightened lemur beneath the frozen surface of Europa, one of Jupiter's moons.

Europa is primarily known as the moon where college students used to go backpacking in the 80s and 90s before Goa went mainstream. The moon, one of many circling Jupiter, was discovered some time ago by Galileo Galilei, an early astronomer from economically troubled Italy who was recently and bizarrely invoked by Rick Perry in defense of global warming denial despite that fact that Texas looks likely to be suffering from severe, climate-change induced drought for at least the next ten years (is God angry at Texas?)

(Warning! Some of the preceding links may not be strictly relevant to the topic at hand.)

Returning to the topic at hand, Europa is also famous for hosting a giant frozen ocean containing enough salt water to cover its entire surface – more water than in all of the Earth's oceans. Deep underneath lurks the liquid lake currently hypothesized.

How lakes are formed on Jupiter's moon Europa

From NASA:

NASA's Galileo spacecraft, launched by the space shuttle Atlantis in 1989 to Jupiter, produced numerous discoveries and provided scientists decades of data to analyze. Galileo studied Jupiter, which is the most massive planet in the solar system, and some of its many moons.

One of the most significant discoveries was the inference of a global salt water ocean below the surface of Europa. This ocean is deep enough to cover the whole surface of Europa and contains more liquid water than all of Earth's oceans combined. However, being far from the sun, the ocean surface is completely frozen. Most scientists think this ice crust is tens of miles thick.

"One opinion in the scientific community has been if the ice shell is thick, that's bad for biology. That might mean the surface isn't communicating with the underlying ocean," said Britney Schmidt, lead author of the paper and postdoctoral fellow at the Institute for Geophysics, University of Texas at Austin. "Now, we see evidence that it's a thick ice shell that can mix vigorously and new evidence for giant shallow lakes. That could make Europa and its ocean more habitable."

Schmidt and her team focused on Galileo images of two roughly circular, bumpy features on Europa's surface called chaos terrains. Based on similar processes seen on Earth -- on ice shelves and under glaciers overlaying volcanoes -- they developed a four-step model to explain how the features form. The model resolves several conflicting observations. Some seemed to suggest the ice shell is thick. Others suggest it is thin.

This recent analysis shows the chaos features on Europa's surface may be formed by mechanisms that involve significant exchange between the icy shell and the underlying lake. This provides a mechanism or model for transferring nutrients and energy between the surface and the vast global ocean already inferred to exist below the thick ice shell. This is thought to increase the potential for life there.

The study authors have good reason to believe their model is correct, based on observations of Europa from Galileo and of Earth. Still, because the inferred lakes are several miles below the surface, the only true confirmation of their presence would come from a future spacecraft mission designed to probe the ice shell. Such a mission was rated as the second highest priority flagship mission by the National Research Council's recent Planetary Science Decadal Survey and is being studied by NASA.

And if you'd care to have a look for yourself, here's a handy animation showing how lakes form beneath the thick, densely frozen shell of Europa.