Orateur
Description
Mercury is one of the two terrestrial planets in our Solar System possessing an intrinsic magnetic field. Being the closest planet to the Sun and having a weak magnetic field, the Hermean magnetic environment is rapidly changing and forms a tightly coupled system with the planet’s core and surface. Its closeness to the Sun causes Mercury’s surface to undergo extreme conditions, with continuous space weathering that can eject atoms from the surface to form a tenuous atmosphere called an exosphere. As these atoms become ionized, they drift along the magnetic field lines and populate the magnetosphere of Mercury. Part of these ions can re-impact the surface and eject surface atoms, forming a strong coupling between the magnetosphere, the exosphere, and the surface. More than fifty years after the Mariner 10 mission confirmed the presence of Mercury’s magnetic field (Ness et al. 1974), the structure of Mercury’s magnetosphere and its ionic composition remain poorly understood. The ESA/JAXA BepiColombo mission is currently cruising towards Mercury to study the Hermean environment, from the planet's surface up to its magnetosphere.
The Mass Spectrum Analyzer (MSA) on board the ESA/JAXA BepiColombo mission collected some data during its cruise phase and during the different planetary swing-bys. The instrument measures the ions’ energy, and the Time-Of-Flight (TOF) of the ions entering MSA TOF chamber. Using the data acquired during the different swing-bys of Mercury and taking advantage of their unique trajectories, we identified different regions of Mercury’s magnetic environment and their associated ionic populations. This work will help better understand the dynamic magnetosphere of Mercury's and sets the path for the analysis of the data that will be acquired by MSA during the orbital phase starting in 2027.