What lurks beneath the volcanoes of Jupiter's moon Io? NASA's Juno probe just took a peek - Space

What the report says

Space.com reported that NASA’s Juno spacecraft has used its Microwave Radiometer to measure heat below the surface of Io, Jupiter’s intensely volcanic moon, giving scientists a new view of the processes driving its eruptions. The data came from close passes on Dec. 30, 2023, and Feb. 3, 2024, when Juno observed roughly 6 to 20 feet beneath Io’s exterior rather than only measuring surface temperatures.

According to the report, the instrument detected subsurface temperatures more than 40 degrees Fahrenheit above what sunlight could account for, as well as localized warmer areas 18 to 36 degrees Fahrenheit hotter than nearby terrain. Researchers also found evidence that much of Io’s surface may be smoother and lower-density than expected, possibly because it is repeatedly covered by porous volcanic ash, sulfur frost and other eruptive material.

The findings matter because Io is the most volcanically active known world in the solar system. Unlike Earth, where much volcanic heat is linked to radioactive decay, Io is heated by tidal forces as Jupiter’s gravity continually stretches and compresses the moon. Scientists are considering whether the observed heat is moving upward through the crust from Io’s molten interior or comes from cooling lava trapped near the surface.

Space.com said the work could influence how researchers study volcanoes beyond Io, including on Earth, Mars, Venus and the moon. The same microwave approach may also help investigate icy moons such as Europa and Ganymede, where subsurface oceans are thought to exist. The study was reported as published July 22 in the Journal of Geophysical Research: Planets.