Hermean Complex Craters Seen in a New Light - First Results from MERTIS MSB#5

Kurzfassung

Studying complex impact craters and especially their ejecta and central peaks provides insights into the composition of a planet's subsurface. These materials likely originate from great depth, depending on factors such as crater size, target properties, and impact conditions [1]. This study aims to enhance our understanding of Mercury's crustal stratigraphy. Using data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission [2], several studies [3,4] already investigated the spectral properties of 121 globally distributed impact craters on Mercury's surface in the wavelength range of 300 - 1450 nm using MESSENGER’s Mercury Atmospheric and Surface Composition Spectrometer (MASCS) [5]. These studies identified a potential global N-S dichotomy in the composition of the shallow crust and short-range horizontal heterogeneities. During BepiColombo’s 5 th swing-by at Mercury (MSB#5) on December 1 st , 2024, the Mercury Radiometer and Thermal Infrared Spectrometer (MERTIS) [6-8] acquired spectral data of the Hermean surface in the wavelength range of 7-14 μm for the first time from a spacecraft. The obtained spectral data cover 186 complex impact craters which have been previously covered by MASCS [4]. For this study we only focus on those 48 craters that are covered by pixels from MERTIS which only lie within the crater, as we want to compare those measurements with spectra from the central peaks taken from the MASCS included in the Mercury Surface Spectroscopy (MeSS) database.