Dawn at Mercury: BepiColombo Science Begins!

Sae Aizawa (LPP Paris)

Mercury, the closest planet to the Sun, possesses a global intrinsic magnetic field that sustains a small and highly dynamic magnetosphere. Strongly influenced by the solar wind, this magnetosphere is closely coupled to Mercury’s surface and tenuous exosphere. How are particles supplied, accelerated, and transported within this system?

The ESA–JAXA BepiColombo mission will investigate these questions through complementary measurements from its two spacecraft, Mio and MPO, with nominal science operations scheduled to begin in April 2027.

In this seminar, I will first review what we have learned from MESSENGER about Mercury’s magnetosphere and exosphere, and the questions that remain open. I will then present recent BepiColombo flyby results, focusing on electron injections and planetary-ion dynamics. I will discuss what these observations tell us about particle exchange between the surface, exosphere, and magnetosphere, and the role of plasma kinetic processes, including wave–particle interactions, in particle acceleration and transport. I will also outline what we expect to learn from BepiColombo’s upcoming orbital observations. I will conclude by discussing what Mercury can tell us about the interaction between close-in rocky exoplanets and their host stars.