Overview
- Juno’s Microwave Radiometer recorded temperatures rising by more than 40°F several feet below Io’s surface during close flybys on Dec. 30, 2023, and Feb. 3, 2024.
- The team offers two viable explanations for the signal: a steady conductive heat flow of roughly 1 to 3 watts per square meter or cooling lava flows capped by about 9 to 11 meters of solid crust covering roughly 10% of the surface.
- A prominent subsurface anomaly near the Zal Montes Patera complex is about 10–20°C warmer than its surroundings and coincides with an active lava flow seen by Juno.
- Long-wavelength microwave returns show broad, smooth plains covered by very low-density deposit layers that resemble pumice or fluffy volcanic ash rather than solid rock.
- Scientists say the unexpected ability to see beneath a rocky crust with an MWR refines models of Io’s interior and could be applied to study heat transport on other icy or volcanic worlds and improve volcanic monitoring on Earth.