Abstract DGP2026-92

BepiColombo is a cornerstone mission of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA), dedicated to the exploration of Mercury (1, 2). As the innermost and least explored terrestrial planet, Mercury occupies a unique position in planetary science: its close proximity to the Sun gives rise to extreme thermal conditions and intense space weathering, while its surface preserves records of early Solar System processes. BepiColombo is designed to address long-standing questions regarding Mercury’s origin, internal structure, surface composition, exosphere, and magnetosphere through coordinated, multi-instrument observations from dual orbiters.

The mission comprises two spacecrafts: the Mercury Planetary Orbiter (MPO), focused on the planet itself, and the Mercury Magnetospheric Orbiter (MMO), dedicated to the magnetosphere. This dual-spacecraft configuration enables, for the first time, a comprehensive and coupled view of Mercury as a system, linking surface processes, internal structure and dynamics, and space–environment interactions.

Surface and compositional studies are central to the mission, as Mercury’s surface records a complex geological history marked by extensive volcanism, global contraction, and impact cratering. BepiColombo aims to define surface mineralogy and geochemistry, thereby testing competing hypotheses for Mercury’s formation, such as high-temperature condensation, mantle stripping, or volatile-rich accretion. High-resolution imaging spectroscopy will enable global mapping of geological units and improved age dating through crater statistics and space-weathering effects.

Within this framework, the Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) (3) aboard MPO provides key observations in the thermal infrared spectral range. MERTIS is specifically tailored to investigate surface mineralogy and thermophysical properties, exploiting Mercury’s extreme day–night temperature variations. Its measurements allow discrimination between major silicate minerals, including feldspar- and pyroxene-rich lithologies, while its radiometric channels provide surface temperature and thermal inertia information. Together, these data constrain regolith grain size, degree of space weathering, and physical structure, and help link compositional variations to geological units such as volcanic plains, impact ejecta, and tectonic features.

MERTIS observations are highly complementary to measurements at visible and near-infrared wavelengths, filling a critical gap in compositional analysis and enabling a more robust interpretation of Mercury’s surface materials. In addition, synergies with the BepiColombo Laser Altimeter (BELA) (4) provides essential context for interpreting thermal and compositional variations in terms of surface roughness, slopes, and topography.

In summary, BepiColombo represents a major step forward in the exploration of Mercury and the study of rocky planets. Through its integrated payload and the combined analysis of surface, interior, and magnetospheric data—supported by instruments such as MERTIS and BELA—the mission will significantly advance our understanding of planetary processes operating under extreme conditions, with implications extending well beyond Solar System.

 

References:

1, Benkhoff, J., et al., Space Sci Rev, 2021

2, Jones, G. and Murakami, G., EPSC-DPS, 2025

3, Hiesinger, H., et al., Planetary and Space Science, 2010

4, Thomas et al., Space Sci Rev, 2021