New findings from NASA’s Juno spacecraft provide a more complete picture of how widespread lava lakes are on Jupiter’s moon Io and include information for the first time about the volcanic processes operating there. These results come courtesy of Juno’s JIRAM instrument, provided by the Italian Space Agency, which “sees” in infrared light.
Io has intrigued astronomers since 1610, when Galileo Galilei first discovered the Jovian moon, which is slightly larger than Earth’s Moon. Some 369 years later, NASA’s Voyager 1 spacecraft captured a volcanic eruption on the moon. Later missions to Jupiter, with more flybys of Io, discovered additional plumes, along with lava lakes. Scientists now believe that Io, which is stretched and compressed like an accordion by neighboring moons and Jupiter itself, is the most volcanically active world in the solar system. But while there are many theories about the types of volcanic eruptions on the moon’s surface, there is little data to support them.
In both May and October 2023, Juno flew by Io, approaching to within about 35,000 kilometers and 13,000 kilometers, respectively. Among Juno’s instruments that could observe the seductive moon well was JIRAM.
Designed to capture infrared light (not visible to the human eye) emerging from the depths of Jupiter, JIRAM probes the climate layer up to 50 to 70 kilometers below the gas giant’s cloud tops. But during Juno’s extended mission, the mission team also used the instrument to study the moons Io, Europa, Ganymede and Callisto. JIRAM Io images showed the presence of bright rings surrounding the ground of numerous hot spots.
“The high spatial resolution of JIRAM’s infrared images, combined with Juno’s favorable position during flybys, revealed that the entire surface of Io is covered by lava lakes contained in caldera-like features,” said Alessandro Mura, co-author of the study. Juno researcher at the National Institute of Astrophysics in Rome. “In the region of Io’s surface where we have the most complete data, we estimate that about 3% is covered by one of these molten lava lakes.” (A caldera is a large depression that forms when a volcano erupts and collapses.)
Fire-breathing Lakes
Data from JIRAM’s Io flyby not only highlights the moon’s abundant lava reserves, but also provides insight into what may be happening beneath the surface. Infrared images of several lava lakes on Io show a thin circle of lava at the edge, between the central crust that covers most of the lava lake and the lake walls. Melt recycling is implied by the lack of lava flows at and beyond the lake edge, indicating that there is a balance between melt that has erupted into the lava lakes and melt that circulates back to the lake. underground system.
“Now we have an idea of what the most common type of volcanism is on Io: huge lava lakes where magma rises and falls,” Mura said. “The lava crust is forced to break against the lake walls, forming the typical lava ring seen in Hawaiian lava lakes. The walls are likely hundreds of meters high, which explains why magma is not generally observed spilling out of the pateras” (bowl-shaped forms created by volcanism) “and moving across the surface of the moon.” .
JIRAM data suggest that most of the surface of these hot spots on Io is composed of rocky crust that moves up and down cyclically as a contiguous surface due to the central upwelling of magma. In this hypothesis, because the crust touches the walls of the lake, friction prevents it from sliding, causing it to deform and eventually break off, exposing the lava just below the surface.
An alternative hypothesis is also possible: magma is erupting in the middle of the lake, spreading and forming a crust that sinks along the edge of the lake, exposing the lava.
“We’re just starting to dig into the JIRAM results from close flybys of Io in December 2023 and February 2024,” said Scott Bolton, Juno principal investigator at the Southwest Research Institute in San Antonio. “The observations show new and fascinating information about Io’s volcanic processes. “Combining these new results with Juno’s long-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.”
Juno executed its 62nd flyby of Jupiter, which included a flyby of Io at an altitude of approximately 29,250 kilometers on June 13. The 63rd flyby of the gas giant is scheduled for July 16.
