Overview – what is this about?


The atmospheric loss from the moon Io is the main source of material for the vast magnetosphere of our largest Solar System planet Jupiter. Io is also the volcanically most active body in the Solar System and the volcanism plays a key role for sustaining the moon’s atmosphere. Within the magnetosphere and plasma community, it is therefore very often assumed that aperiodic changes or transient phenomena in Jupiter’s magnetosphere are triggered by sudden and strong changes in the mass loss from Io, supposedly related to volcanic outbursts. The magnetospheric effects – presumably arising from Io’s volcanism – have been topic of an earlier ISSI team (ID 388).

Contradictory understandings and missing evidence

The assumption of direct “volcanic control” of the magnetosphere is, however, neither supported by the current understanding of the dynamics of Io’s atmosphere, nor by observations of the atmospheric abundance. Io’s atmosphere has been found to be primarily sustained by sublimation of surface frost and to a lesser extent by direct outgassing at volcanoes. The atmospheric loss is predominantly through collisions with the surrounding plasma and not through direct thermal escape. Changes in volcanic activity are thus not expected to lead to strong changes in the atmospheric density or loss rate. Furthermore, observational monitoring of the atmospheric gas column density has not provided any evidence for sudden changes but only revealed seasonal atmospheric variability. On the other hand, there are so far no alternative explanations for the observed magnetospheric changes from studies claiming “volcanic control”. And some correlations indeed point to Io as the trigger.

Task for a team!

In order to address the issue of these allegedly contradictory understandings of the variability of Io’s mass loss, we gathered an international team with leading experts in the areas of Io’s volcanism, atmosphere and the magnetospheric environment. While this topic is very defined, the Io-Jupiter system is the prime example for various geophysical and plasma physical processes; a correct understanding of Io’s role is crucial, far beyond Jupiter and the Solar System.

We are currently writing a review paper around Io’s mass loss based on our team discussions, see Objectives.

If you want to know more or are interested in contributing to this effort, please contact Lorenz Roth (via lorenzr at kth.se)!