Initial results from MGNS measurements of neutron and gamma-ray emission from Mercury’s surface during flybys of the ESA/JAXA BepiColombo mission

The Mercury Gamma-ray and Neutron Spectrometer (MGNS) onboard the MPO orbiter of the ESA BepiColombo mission is designed to measure gamma-ray and neutron emission from the surface of Mercury to study its elemental composition. The spacecraft launched in October 2018 is traveling in a heliocentric orbit approaching the Mercury orbit; the cruise phase will last until November 2026. Before the planned insertion into orbit around the planet, BepiColombo has performed six gravity-assist flybys of Mercury. This paper presents the first direct measurements of neutron and gamma-ray emission from the surface of Mercury obtained by MGNS during these flybys. The first data collected during the flybys demonstrate that the instrument is ready to begin the main mapping phase of the mission.