Juno spacecraft reveals subsurface heat anomalies on Jupiter’s moon Io
New findings from NASA’s Juno mission identify significant internal heating within the upper tens of metres of Io’s crust, with distinct thermal anomalies linked to active volcanic regions.
Data captured by the Microwave Radiometer (MWR) aboard NASA’s Juno spacecraft has revealed significant heat rising from beneath the surface of Jupiter’s moon Io. While infrared instruments typically measure only the temperature of the moon’s surface, the MWR’s lowest frequency channels, operating at 0.6 and 1.25 gigahertz, are capable of penetrating between two and six metres into the crust. This capability allows scientists to detect a distinct temperature gradient within the upper tens of metres of Io’s interior, providing a view of subsurface conditions that surface observations cannot offer.
The resulting thermal map highlights a prominent subsurface heat anomaly located between 60 and 120 degrees west longitude. This region is 10 to 20 degrees Celsius warmer than the surrounding areas, a differential that corresponds directly with the Zal Montes Patera complex. It was in this specific area that Juno’s Stellar Reference Unit previously observed an active lava flow, suggesting a strong correlation between the subsurface heat source and surface volcanic activity.
A second major subsurface heat source has also been identified near the moon’s equator, stretching from 0 to 50 degrees west longitude. These distinct microwave anomalies indicate that significant internal heating is occurring within the crust, rather than being confined solely to the surface. The data provides a more comprehensive understanding of the thermal dynamics driving Io’s intense geological activity.
Contrasting with these intense hot spots, the map illustrates the broader thermal landscape of the moon. Yellow regions, representing intermediate temperatures, warm up to approximately -123 degrees Celsius as they approach the equator. Meanwhile, green areas, primarily visible toward the higher northern latitudes, indicate the coolest subsurface temperatures, dropping to around -183 degrees Celsius near the pole.
The Juno mission is managed by NASA’s Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, for principal investigator Scott Bolton of the Southwest Research Institute in San Antonio. Juno is part of NASA’s New Frontiers Program, which is managed at NASA’s Marshall Space Flight Center in Huntsville, Alabama. The MWR instrument was built by JPL, while Lockheed Martin Space in Denver built and operates the spacecraft.
