On Jupiter’s moon Io, lava creeping under the frost can lead to flights of towering dunes.

This find, described on April 19 in Natural communicationssuggests that dunes it may be more common in other worlds than previously thoughtalthough lumps can form in strange ways.

“In a sense, these [other worlds] they look more familiar, “said George MacDonald, a planetary scientist at Rutgers University in Piscataway, New Jersey. “But the more you think about it, the more exotic they feel.

Io is a world crowded with erupting volcanoes created when the gravitational forces of Jupiter and some of its other moons pull Io and generate heat (SN: 08/06/14). About 20 years ago, scientists reported another type of characteristic of the dynamic surface of Io – hills. The characteristics are similar to dunes, but this may not be the case, scientists say, because Io’s atmosphere is too thin for winds to develop dunes.

But in recent years, dune-like features have been found on comet 67P (SN: 21.09.20) and Pluto (SN: 24.08.21), planetary bodies that also lack a dense atmosphere. Inspired by these alien dunes, MacDonald and his colleagues reconsidered Io’s mysterious lumps. All they needed was some kind of air force to sculpt the dunes of the moon.

Powerful steam explosions occur on Earth when streams of molten rock collide with bodies of water. While water is not found in Io, sulfur dioxide frost is widespread. So scientists suggest that when lava slowly flows into and just below a layer of frost, jets of sulfur dioxide gas can explode from frost. These jets could send grains of rock and other material to fly and form dunes.

Researchers estimate that an advancing stream of lava buried below at least 10 centimeters of frost could sublimate some of the frost into pockets of hot steam. When enough steam accumulates and the pressure becomes high enough to match or overcome the weight of the frost, the steam can explode at speeds above 70 kilometers per hour. These bursts can drive grains with a diameter of 20 micrometers to 1 centimeter, the team estimates.

Analysis of images of Io’s surface, collected by NASA’s now-defunct Galileo spacecraft, revealed highly reflective streaks of material radiating outward over the dunes in front of lava flows, possibly material newly deposited at the time by steam jets.

lumps similar to dunes on the surface of Io
This image, taken by NASA’s now-defunct Galileo spacecraft, shows dune-like lumps on Jupiter Io’s third largest moon. The dark area (lower left) is a stream of lava, and the bright streaks that radiate outward may be evidence of material scattered by jets of frost bursting with frost.JPL-Caltech / NASA, Rutgers Univ.

Moreover, the use of images to measure hills has shown that their dimensions are consistent with those of the dunes of other planetary bodies. Some of the Ionian dunes are over 30 meters high, the team estimates.

“I think a lot [scientists] he looked at them and thought, hey, these could really be dunes, ”said Gianni Radebo, a planetary scientist at Brigham Young University in Provo, Utah, who was not involved in the study. “But what’s exciting about this is that they’ve come up with a good physical mechanism to explain how it’s possible.”

Yo is usually considered a world of volcanoes. The possibility of dunes suggests more could be happening there than scientists thought, McDonald said. “It definitely adds a layer of complexity.”

Lava and frost may form the mysterious lumps on Jupiter’s moon Io

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