NASA's Juno probe reveals what lies beneath Io's volcanic crust
In short: Jupiter's moon Io is a world of extreme violence, featuring hundreds of volcanoes and lava fountains that reach dozens of miles into space. But for the first time, NASA has looked past the surface to see how this heat actually moves through the moon's rocky interior.
Io is defined by its status as the most volcanically active world in our solar system. This intensity is driven by a gravitational tug-of-war: Jupiter's massive gravity, combined with precise pulls from the neighboring moons Europa and Ganymede, constantly stretches and squeezes Io. Unlike Earth, where volcanoes are primarily fueled by radioactive decay, Io’s internal heat comes from this mechanical stress.
In late 2023 and early 2024, NASA's Juno spacecraft used its Microwave Radiometer (MWR) to probe roughly six to 20 feet beneath Io's surface. This was a significant technical shift; while researchers previously relied on infrared observations that only detected surface temperatures, the MWR allowed scientists to see how heat moves through the crust for the first time.
The data revealed startling results: temperatures rise by more than 40 degrees Fahrenheit just a few feet underground—a jump far too large to be caused by sunlight alone. The subsurface heat map also identified localized regions measuring between 18 and 36 degrees Fahrenheit warmer than the surrounding terrain. Scientists believe this heat either rises steadily from a molten interior through a conductive crust or originates from pockets of cooling lava trapped just below the surface.
The findings have unexpected implications for Earth. Scott Bolton, Juno's principal investigator, suggests that using similar MWR-type instruments near terrestrial volcanoes could provide new insights into how our own planet's volcanic systems function. Despite its jagged appearance, much of Io's surface is actually remarkably smooth, likely blanketed by porous layers of volcanic ash and sulfur frost that continually bury older terrain.
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Sources
- Summary by Intellect · source: What NASA Found on Io
- Also: Io
- Also: What lurks beneath the volcanoes of Jupiter's moon Io? NASA's Juno probe just took a peek | Space
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