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Near‐Ultraviolet to Near‐Infrared Spectral Properties of Hollows on Mercury: Implications for Origin and Formation Process
Author(s) -
Barraud O.,
Doressoundiram A.,
Besse S.,
Sunshine J. M.
Publication year - 2020
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
eISSN - 2169-9100
pISSN - 2169-9097
DOI - 10.1029/2020je006497
Subject(s) - mercury (programming language) , ultraviolet , multispectral image , geology , spectral signature , infrared , spectral bands , remote sensing , spectral line , spectral resolution , mineralogy , optics , materials science , physics , astronomy , computer science , programming language
Among the geological features revealed by the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry and Ranging) mission on the surface of Mercury, hollows are the most surprising and least understood. Possibly related to volatile components, hollows are small depressions, surrounded by bright halos and are not observed on any other surfaces in our solar system. Previous analysis of multispectral data obtained by Mercury Dual Imaging System (MDIS) has shown that some hollows have weak spectral absorption features centered at around 600 nm. In this work, we analyzed four hollows with observations acquired by the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on board MESSENGER with more than 230 spectral channels from the near‐ultraviolet to the near‐infrared. Unlike previous MDIS multispectral data, the MASCS reflectance spectra exhibit no absorption features in the MDIS wavelength range. However, we found that hollows have unique spectral properties in the near‐ultraviolet, with a spectral curvature between 300 and 600 nm that is distinctly different from other geological units. Moreover, we used MASCS observations with the best available spatial resolution (<0.5 km/pixel) to analyze both parts of a hollow: the flat floor and the surrounding halo. Our results support the hypothesis that hollows form by a sublimation process and scarp retreat.