NASA’s Juno mission, initially dedicated to exploring Jupiter, has expanded its scope to observe the gas giant’s moons, leading to remarkable discoveries. The latest finding involves the Jovian moon Io, revealing it to be covered in “fire-breathing” lava lakes. Utilizing its Jovian Infrared Auroral Mapper (JIRAM) instrument, a project developed by the Italian Space Agency, Juno has captured infrared images showcasing these lakes scattered across Io’s surface. These images highlight hot rings of lava encircling a cooler crust. The rings appear as bright white in the images, with a thermal signature ranging between 450 and 1,350 degrees Fahrenheit (232 and 732 degrees Celsius). In contrast, the rest of the lake exhibits a much cooler temperature, measuring around minus 45 degrees Fahrenheit (minus 43 degrees Celsius).
Alessandro Mura, a Juno co-investigator from the National Institute for Astrophysics in Rome, stated, “We now have an idea of what is the most frequent type of volcanism on Io: enormous lakes of lava where magma goes up and down.” He further explained that the lava crust is forced to break against the lake’s walls, resulting in the characteristic lava ring observed in Hawaiian lava lakes. The leading hypothesis suggests that magma undergoes upwelling within these lava lakes, causing them to rise and fall. When the crust contacts the lake’s walls, which can be hundreds of meters tall, the friction leads to its breakage, exposing the lava along the lake’s edge.
An alternative hypothesis proposes that magma rises in the center of the lake, pushing the crust outwards until it sinks along the lake’s edge, once again exposing the lava and forming those lava rings. There remains much to explore about Io, particularly regarding Juno’s infrared imagery. Scott Bolton, the principal investigator for Juno at the Southwest Research Institute in San Antonio, emphasized the significance of these findings, stating, “We are just starting to wade into the JIRAM results from the close flybys of Io in December 2023 and February 2024.” He added, “Combining these new results with Juno’s longer-term campaign to monitor and map the volcanoes on Io’s never-before-seen north and south poles, JIRAM is turning out to be one of the most valuable tools to learn how this tortured world works.”
