On the Outer Solar System moon-magnetosphere interactions: the unique case of Ganymede

Thanks to the analysis of data obtained during past and current missions to the outer solar system, as well as telescope observations of giant planets and their moons, our knowledge on the moon-magnetosphere interactions has been singificantly grown in the recent years. Theoretical progress in the field of space plasma physics and the performance of numerical simulations have significantly contributed in our better understanding of the near-moon environments and the underlying physical processes as well as their variability both at long and short terms.

There is a wide variety of moon environments in the outer solar system depending both on the bodies properties and the specific characteristics of the planetary magnetosphere in which they are embedded. Although each case of moon-magnetosphere interaction is unique, a comparative planetary science context can often result useful in our overall understanding of the related physical processes.

The interaction between Ganymede and its surrounding plasma environment is of special interest, mainly because this moon possesses its own mini-magnetosphere. Reconnection allows Jovian plasma and energetic ions to access the moon’s surface where they precipitate following patterns that depend on the position of Ganymede with respect to the Jupiter plasma sheet. An in depth understanding of the properties of the plasma-magnetosphere interactions in the vicinity of Ganymede will reveal the details determining the ion-surface processes responsible for the exosphere generation as well as the weathering and the surface evolution history.

In this review, some paradigms of moon-magnetosphere interactions in the outer solar system will be discussed and special emphasis to the unique case of Ganymede will be given. The role of comparative science in getting the global picture and addressing long-lasting open questions in this field will be also addressed.