Jupiter’s moon Io is bristling with volcanoes like a quilled porcupine and is the most volcanically active world in the solar system. About 150 of the 400 active volcanoes on Io are erupting at any given time. It constantly spews lava and gas; a veritable volcanic excrement factory.
And thanks to Juno’s Jovian Infrared Auroral Mapper (JIRAM) imaging Jupiter and its surroundings, we now know a lot more about what a gloriously hot mess Io is.
“The high spatial resolution of the JIRAM infrared images, combined with the favorable position of Juno during the flybys, revealed that the entire surface of Io is covered by lava lakes contained in caldera-like formations,” says astrophysicist Alessandro Mura of the National Institute for Astrophysics in Italy.
“In the area of ​​Io’s surface where we have the most complete data, we estimate that about 3 percent of it is covered by one of these molten lava lakes.”
Io is the victim of a complex game of gravitational tug-of-war. Its orbit around Jupiter is not perfectly circular, meaning that the attraction between the moon and the planet changes over time. In addition, Jupiter’s other Galilean moons—Callisto, Europa, and Ganymede—have enough mass to exert their own gravitational influence on Io.
The result of all this opposing gravitational influence is stress on Io’s interior, generating heat that gushes out in the form of volcanism. The moon is one hot potato.
While we have a pretty good understanding of the dynamics that squeeze and stretch Io’s interior, and the effect it all has on the wider environment around Jupiter and the gas giant itself, there’s a lot we don’t know about how volcanism plays out on Io’s surface.
Fortunately, that fell under Juno’s purview. As the probe explores Jovian space, it makes flybys of some of its moons and uses its instruments to collect data closer and more personal than we’ve ever achieved before. The probe recently made a series of very close flybys of Io, revealing the sulphurous moon in stunning detail.
We saw clouds of real volcanic eruptions and lakes of lava glistening on the surface. Now scientists have analyzed some of that data, particularly infrared observations captured by JIRAM, which reveal thermal signatures on Io’s surface.
From this, scientists were able to observe lava lakes, which consist of a ring of exposed liquid lava overlapping at the edges, with a solidifying crust in the center of the molten lake, forming high lake walls around a basin-like floor in which the lava collects. This finally reveals the most dominant form of volcanism on Io.
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“We now have an idea of ​​what the most common type of volcanism is on Io: huge lava lakes where magma rises and falls,” says Mura.
“The lava crust is forced against the walls of the lake, creating the typical lava ring seen in Hawaiian lava lakes. The walls are probably hundreds of meters high, which explains why magma is not generally observed to spill out of the paterae and move.” over monthly Surface.”
This suggests that lava enters the floor from a magma reservoir below the surface and flows out the same way, causing the lakes to rise and fall. The central crust rubs against the walls of the lake as it moves up and down, breaking off the edges, resulting in a ring of lava around the perimeter of the lake.
Another possibility is that the edges of the crust become loaded and sink under the lava, again leading to a ring.
“The observations reveal fascinating new information about volcanic processes on Io,” says Juno principal investigator Scott Bolton of the Southwest Research Institute in the US.
“Combining these new results with Juno’s longer-term campaign to monitor and map volcanoes at Io’s never-before-seen north and south poles, JIRAM is proving to be one of the most valuable tools for learning how this tortured world works.”
The research was published in The nature of communication.