NASA's Juno Reveals New Insights on Jupiter's Moon Io

NASA's Juno spacecraft has revealed that Jupiter's moon Io is emitting heat at levels potentially hundreds of times higher than scientists previously estimated. This finding, derived from Juno's data, indicates that about half of Io's heat output is concentrated in just 17 out of 266 known volcanic sources.

Team leader Federico Tosi of the National Institute for Astrophysics highlights that the earlier underestimation was not due to a lack of data, but rather the interpretation of Juno's measurements, particularly in the infrared M-band.

This M-band is sensitive to the highest temperatures, capturing only the bright, incandescent areas of volcanoes while overlooking cooler, yet expansive regions that also contribute significantly to heat emission.

Tosi compares this to estimating the brightness of a bonfire by observing only the flames, neglecting the energy released by the surrounding embers. Rethinking how Juno's JIRAM data is analyzed has led to new insights into Io's volcanic structure.

The majority of Io's volcanoes feature a hot, bright outer ring, surrounded by a cooler, solid central crust. This cooler crust, while less visually prominent in the M-band, covers a larger surface area and emits a substantial amount of heat.

Consequently, the actual heat flux from Io is now believed to be vastly underestimated, prompting a reassessment of the moon's energy balance. This new understanding also raises questions about the existence of a global magma ocean beneath Io's surface, a feature that cannot be conclusively ruled out.

Tosi cautions that while their findings do not confirm such an ocean, they also do not dismiss it, emphasizing the limitations of current data in drawing definitive conclusions. Future missions, including ESA's Juice and NASA's Europa Clipper, may not provide the detailed observations of Io necessary to resolve these questions, as their focus will be on other moons in the Jovian system.

However, the research team's findings lay a crucial foundation for interpreting future spacecraft observations of Io, potentially shedding light on the processes driving its extreme volcanism. Tosi concludes that these insights could inform the design of future missions specifically aimed at studying Io, which is crucial for understanding this intensely volcanic world.