Study Led by JPL Finds Heat Rising Beneath the Surface of Jupiter’s Volcanic Moon Io

NASA’s Juno mission has successfully captured the first-ever subsurface temperature measurements of Io. This moon remains the most volcanically active body in our solar system, and these new findings offer a clear look at what happens beneath its crust.

Researchers from the Jet Propulsion Laboratory found that Io’s subsurface temperatures rise significantly as you go deeper. Specifically, the data shows an increase of more than 40 degrees Fahrenheit just a few feet into the surface. This gradient is far steeper than what solar heating alone could produce, confirming intense internal activity powered by tidal forces from Jupiter.

The spacecraft collected this information during two close flybys in late 2023 and early 2024. By using the Microwave Radiometer, the team measured thermal emissions at depths ranging from a few inches to tens of feet. These readings suggest two potential scenarios for the heat movement: a steady flow through a conductive crust or heat emanating from cooling lava flows hidden beneath a 30-foot layer of crust.

Beyond the thermal data, the study revealed that most of the moon’s surface is surprisingly smooth. While Io is famous for its mountains, the areas between them resemble the Great Plains of North America. Scientists noted that this material has a low density, similar to fluffy volcanic ash or pumice, rather than solid rock. This discovery helps researchers understand how heat migrates from the interior of planetary bodies toward their surface.

The implications of this work reach beyond Jupiter. The team believes this method for peering into a rocky surface could help scientists better understand volcanic activity on Earth. By studying these thermal signatures, experts can gather new information about tidal heating throughout the solar system, which serves as a critical energy source for moons with subsurface oceans.