NASA Maps Io Subsurface Heat at 1-3 W/m2 as Jupiter Tides Lift Ground 100 Meters
Updated
Updated · spacedaily.com · Aug 21
NASA Maps Io Subsurface Heat at 1-3 W/m2 as Jupiter Tides Lift Ground 100 Meters
3 articles · Updated · spacedaily.com · Aug 21
Summary
July 2026 NASA results gave the first broad subsurface temperature measurements of Io, with Juno’s microwave radiometer indicating average heat flow of about 1 to 3 watts per square metre.
Those readings suggest smooth, low-density material blankets much of the moon, while unusually warm layers a few metres down may be conductive crust or buried lava still cooling.
Jupiter’s gravity drives that heat source: Io’s slightly eccentric 42.5-hour orbit flexes the moon by as much as 100 metres, and the delayed response of warm rock converts orbital energy into internal heat.
Europa and Ganymede keep the process going through a 4:2:1 orbital resonance that preserves Io’s eccentricity, sustaining roughly 400 volcanoes on the Solar System’s most volcanically active world.
The new temperature map also supports a view emerging from Juno’s 2023-24 flybys that Io is mostly solid with localized magma reservoirs, not a shallow global magma ocean.