Ice Europe deformed by an unexpected heat generator

Ice Europe deformed by an unexpected heat generator

This excitement surrounds NASA's Juno mission, which will go into Jupiter’s orbit this summer, and future missions that are planning to explore the ices of its moon, Europe. New research on the strange properties of the lunar cracked crust may reveal some interesting points about the subsurface ocean of Europe.

Researchers from Brown University in Providence, Rhode Island, have combined European observations with computer models and laboratory experiments that will help detect tidal contractions caused by the enormous gravitational field Jupiter. Which in turn can lead to the fact that the fragmented ice of the moon generates more heat than thought, creating new exciting opportunities to search for life in Europe.

Before the NASA Voyager and Pioneer missions completed their missions in the 1970s, and then the Galileo missions in the 1990s, we had little knowledge of the dynamic nature of Jupiter’s satellites. “Scientists expected to see cold, dead spots, but were immediately stunned by their striking surfaces,” said Christine McCarthy, of Columbia University, who conducted research on ice Europe as a graduate student at Brown University. - “There was obviously some kind of tectonic activity - everything moved and crackled. There were also places on Europe that look like melted or mushy ice. ”

It is now known that Europe has a vast subsurface ocean of water, protected by a fragmented ice crust, which seems to move in the same way as the continental plates on Earth. Tidal pressure in the orbit of Europe around Jupiter creates an internal dynamo that gently heats the moon from the core, keeping the ocean in a liquid state. In addition, the movement of the ice plates is believed to generate its own heat through frictional processes at the boundaries. As well as the heat generated by repeated bending of the wire hangers, heat is dissipated through the repeated tidal bends of the European crust within these boundaries. But the small-scale processes behind this tidal dissipation are poorly understood and may have been extremely underestimated.

“People use simple mechanical models to describe ice,” McCarthy said. “They did not study the types of heat flux that would create this tectonics. Thus, we conducted several experiments to try to better understand this process. ”

In order to imitate what may be happening in the bark of Europe, McCarthy led a project to simulate tidal pressure, which will be felt by the ice of Europe in the laboratory. By loading ice samples into a compression device at Brown University, it will be possible to measure the degree of deformation and heat.

So far, no suggestion has been made that most of the heat comes from friction between individual ice granules. This suggests that frictional heating is directly related to the size of the granules. But while changing the size of the ice granules in the samples, McCarthy did not notice any difference in the heat flow. Instead, she realized that most of the heat comes from microscopic defects in the crystal structure of ice, since the ice was deformed. The greater the deformation, the more heat is generated.

“Cristina found that, compared to the models used by the community, ice is more dissipative than people thought,” said colleague Reed Cooper of Brown University. “The beauty of this is that as soon as we get physical order, it becomes surprisingly extrapolational. “These physical features are the first order in understanding the thickness of the shell of Europe. In turn, the thickness of the shell relative to the volumetric chemistry of the moon is important for understanding the chemistry of this ocean. And if you are looking for life, the chemistry of the ocean is an important point. ”

In short, the realization that the microscopic structure of ice generates heat and that the heat generated more than can be obtained by frictional heating helps scientists learn much more about the physics of Europe’s ice crust and, therefore, open a new window to the chemistry of ocean liquid water. below.

As NASA plans to explore one of the most fascinating worlds in the solar system through the future Europe Clipper mission, this basic research will help to better understand the inhabited potential of the mysterious ocean of Europe.

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