The subsurface ocean of Jupiter’s icy moon Europa is heated from below via tidal heating and radioactive decay of the rocky interior, while being cooled from above by its frozen surface. Simulations and lab experiments suggest that this results in convection, whereby heat is transported in rising and sinking plumes of warm and cold water. These plumes are influenced by Europa’s rotation and consequently form jets of alternating east-west oceanic currents. At the surface, the flowing ocean exerts friction on the ice, causing it to move. In new research, planetary scientists from NASA’s Jet Propulsion Laboratory, the University of Oxford and Hokkaido University simulated this process using a large-scale computer model of Europa’s ocean. Their simulations show that the jets can exert enough friction on the ice to be relevant in understanding how the ice shell rotates.
For decades, planetary scientists have debated whether Europa’s icy shell might be rotating faster than the deep interior.
But rather than tying it to the ocean’s movement, they focused on an outside force: Jupiter.
They theorized that as the gas giant’s gravity pulls on Europa, it also tugs on the moon’s shell and causes it to spin slightly faster.
“It was known through laboratory experiments and modeling that heating and cooling of Europa’s ocean may drive currents,” said Dr. Hamish Hay, a researcher at the University of Oxford.
“Now our results highlight a coupling between the ocean and the rotation of the icy shell that was never previously considered.”
“It might even be possible, using measurements gathered by NASA’s upcoming Europa Clipper mission, to determine with precision how fast the icy shell rotates.”
“When scientists compare images gathered by Europa Clipper with those captured in the past by NASA’s Galileo and Voyager missions, they will be able to examine locations of ice surface features and potentially determine if the position of the moon’s…
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