On Jupiter’s moon Io, lava creeping beneath frost might give rise to fields of towering dunes.
That discovering, described April 19 in Nature Communications, means that dunes could also be extra widespread on different worlds than beforehand thought, although the lumps might type in odd methods.
“In some sense, these [other worlds] are looking more familiar,” says George McDonald, a planetary scientist at Rutgers University in Piscataway, N.J. “But the more you think about it, they feel more and more exotic.”
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Io is a world crowded with erupting volcanoes, created when the gravitational forces of Jupiter and a few of its different moons pull on Io and generate warmth (SN: 8/6/14). Around 20 years in the past, scientists reported one other sort of characteristic on Io’s dynamic floor — hummocky ridges. The options resemble dunes, however that couldn’t be the case, scientists reasoned, as a result of Io’s environment is just too skinny for winds to whip up a dunescape.
But in recent times, dunelike options have been found on comet 67P (SN: 9/21/20) and Pluto (SN: 8/24/21), planetary our bodies that additionally lack thick atmospheres. Inspired by these alien dunescapes, McDonald and his colleagues revisited the matter of Io’s mysterious lumps. All they wanted was some sort of airborne power to sculpt the moon’s dunes.
On Earth, highly effective explosions of steam happen when flows of molten rock encounter our bodies of water. While water isn’t discovered on Io, sulfur dioxide frost is pervasive. So the scientists hypothesize that when lava slowly flows into and just below a frost layer, jets of sulfur dioxide fuel may burst from the frost. Those jets may ship grains of rock and different materials flying and forming dunes.
The researchers calculate that an advancing lava movement, buried beneath at the least 10 centimeters of frost, may sublimate a number of the frost into pockets of sizzling vapor. When sufficient vapor accumulates and the strain turns into excessive sufficient to match or overcome the load of the overlying frost, the vapor may burst out at velocities over 70 kilometers per hour. These bursts may propel grains with diameters from 20 micrometers to 1 centimeter in dimension, the workforce estimates.
Analyzing pictures of Io’s floor, collected by NASA’s now-defunct Galileo probe, revealed extremely reflective streaks of fabric radiating outward over dunes in entrance of lava flows — probably materials newly deposited on the time by vapor jets.
What’s extra, utilizing the pictures to measure the hummocky options confirmed that their dimensions align with these of dunes on different planetary our bodies. Some of the Ionian dunes are over 30 meters excessive, the workforce estimates.
“I think a lot of [scientists] looked at those and thought, hey, these really could be dunes,” says Jani Radebaugh, a planetary scientist at Brigham Young University in Provo, Utah, who was not concerned within the examine. “But what’s exciting about it is that they’ve come up with a good physical mechanism to explain how it’s possible.”
Io is usually considered a world of volcanoes. The risk of dunes means that there may be extra happening there than scientists thought, McDonald says. “It certainly adds a layer of complexity.”