(ORDO NEWS) — Europa is the smoothest solid object in the solar system thanks to its thick icy shell.
This ocean makes Europe the main target of scientific research, including two separate orbiters to Jupiter over the next two years will be sent.
While it will take several years for any probe to arrive, scientists are already shedding light on Europa in other ways, gathering information from telescope observations, previous probe flights, laboratory experiments and computer simulations.
In a new study, researchers at Caltech’s Jet Propulsion Laboratory (JPL) in the US and the University of Hokkaido in Japan used NASA supercomputers to investigate a lesser-known feature of Europe: Why is the icy shell spinning faster than the interior?
According to their study, the non-synchronous surface rotation could be caused by ocean currents pushing from below.
This is a big discovery, explains lead author and JPL researcher Hamish Hay, who is now at the University of Oxford; this discovery may provide new clues about what is going on there.
“Prior to this, it was known from laboratory experiments and simulations that the heating and cooling of Europa’s ocean could cause currents,” says Hay.
“Now our results highlight a connection between the ocean and the rotation of the ice shell that has never been considered before.”
The icy shell floats in Europa’s ocean, so it can rotate independently of the rest of the Moon, including the ocean, rocky interior, and metal core.
Scientists have long suspected this, but the forces governing the rotation of the shell have remained mysterious.
Europa is subject to Jupiter’s tidal curvature, which distorts the moon with its powerful gravitational pull.
This colossal tug-of-war is causing cracks in Europa’s icy shell and likely generating some of the mantle and core heat.
It is believed that along with the thermal energy released by radioactive decay, this heat from the bowels of Europa is increasing. across the ocean to a frozen surface, like a pot of water heated on a stove.
Combined with Europa’s rotation and other factors, this vertical temperature gradient should be feeding fairly powerful ocean currents.
And, according to the study’s estimates, these currents could be powerful enough to move the global ice shell overhead. Nobody knows exactly how thick the shell is, but estimates range from 15 to 25 kilometers (15 miles).
While scientists knew that Europa’s icy shell was likely spinning on its own, they focused on Jupiter’s gravitational action. influence as a driving force.
“It was completely unexpected for me that what happens in the circulation of the ocean can be enough to affect the ice shell.
It was a huge surprise,” says study co-author and Europa Clipper Project Scientist Robert Pappalardo of NASA’s Jet Propulsion Laboratory.
“The idea that the cracks and ridges we see on Europa’s surface could be related to the circulation of the ocean underneath is something geologists don’t usually take into account.
I think, “Maybe the ocean does it,” he adds.
The researchers used NASA supercomputers to create a sophisticated ocean simulation of Europa, borrowing techniques that have been used to model oceans on Earth.
These models provide deeper insights into Europa’s water circulation, including how these patterns are affected by ocean heating and cooling.
A key area of research was drag, or the horizontal force of the ocean pushing the ice above it.
Taking drag into account in their simulations, the researchers found that some of the faster currents can create enough drag to speed up or slow down the rotation of Europa’s ice sheet.
Although this effect depends on the speed of the currents, the researchers note that Europa’s internal heating can change over time.
This can lead to a corresponding change in the speed of ocean currents, which in turn will lead to faster or slower rotation of the ice shell.
In addition to helping us understand Europa, this study could be applicable to other oceanic worlds, the researchers say point out where surface features can give clues about the waters hidden below.
“And now that we know about the potential connection of the inland oceans to the surfaces of these bodies, we can learn more about their geological history as well as Europe,” says Hay.
The ESA Jupiter Icy Moons Explorer (JUICE) spacecraft is scheduled to launch in April 2023 to begin a journey to study Jupiter’s three large ocean-bearing moons: Ganymede, Callisto, and Europa.
In late 2024, NASA plans to launch its Europa Clipper orbiter, which will make nearly 50 close flybys to explore the potential habitability of the Moon.
It can even accurately measure how fast Europa’s ice sheet is spinning, according to the authors of the new study.
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