Structural targets of the SIMBIO-SYS instrument suite of BepiColombo: Objectives, categorization and tectonic signficance

Tectonism, fault mechanics and global contraction are major areas of geologic research on Mercury. The Spectrometer and Imagers for MPO BepiColombo Integrated Observatory System (SIMBIO-SYS) instrument suite onboard BepiColombo has three channel observation capabilities, differing in resolution, observation area and frequency, which are poised to offer new insights to our understanding of mercurian tectonics. These channels include 1. the High-Resolution Imaging Channel (HRIC) which provides target oriented observations with panchromatic and color filters, 2. The Visibile-Infrared Hyperspectral Imager (VIHI) which provides global mapping, as well as higher resolution target oriented observations and 3. The Stereo Imaging Channel (STC) which provides global mapping and target oriented observations (Galluzzi et al., 2025). The relationships between local, regional and global tectonics, and the influence of crustal structure and thickness remain major aspects of tectonism on Mercury that are not fully understood (e.g. Galluzzi et al., 2019; Klimczak et al., 2025; Schmidt et al., 2026). These tectonic aspects are incorporated into the scientific objectives specific to SIMBIO-SYS,
which in tandem with gravity data from the Mercury Orbiter Radio Science Expirement (MORE) can be thoroughly addressed by BepiColombo.

There are upwards of 250 planned targets of tectonic interest specific to SIMBIO-SYS. These targets include structures and landforms such as thrusts (or rupes), "fresh" faults (e.g. Watters 2016), graben (e.g. Man et al., 2023), depressions and geological unit contacts, as well as various terrains. Further still are many other targets associated to volcanism and basins which have a shared scientific rationale to tectonism. The significance that these landforms have to our understanding of the geologic history of Mercury cannot be emphasized enough. Considering also that Mercury represents a planetary body that had extensive tectonic activity in its past, yet remained a stagnant lid, data from these targets has the potential to further our understanding of planet evolution and the Solar System in general.

In an effort to convey the scientific contribution that SIMBIO-SYS is prepared to deliver, here we discuss the objectives and importance of these targets, and present specific examples and how each plays a role in addressing scientific questions. The complex structural geology of Mercury stands to demonstrate to us many aspects of fault mechanics and planet evolution that can often go under appreciated when studying the geology of Earth. Thus, the planned targets of tectonic interest captured by SIMBIO-SYS represent a great opportunity to geological science.

Acknowledgments:

We gratefully acknowledge funding from the Italian Space Agency (ASI) under ASI-INAF agreement 2024-18-HH.0.

References:

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