Lunar Mineralogical Imaging for Surface Studies (LuMISS): a new spectrometer for lunar in situ applications

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LuMISS (Lunar Mineralogical Imaging for Surface Studies) is a spectrometer devoted to the study of the lunar regolith from close observation of the lunar surface. The instrument is designed to identify and characterize hydrated minerals, water ice, and anhydrous mineral phases on the lunar surface, thanks to the spectral range extending from UV to IR. Beyond its scientific relevance, LuMISS is intended to support future robotic and human exploration activities by contributing to the identification of scientifically valuable sampling sites and regions of interest for In-Situ Resource Utilization (ISRU).LuMISS (Lunar Mineralogical Imaging for Surface Studies) is a project developed through a collaboration between INAF – Istituto di Astrofisica e Planetologia Spaziali (INAF-IAPS), the University of Pavia (UniPV), and the Italian Space Agency (ASI). The project has been selected within the ESA call “Reserve Pool of Science Activities for the Moon” and is focused on the development of a prototype Visible–Near Infrared (VNIR) spectrometer dedicated to the mineralogical characterization of the lunar regolith. More than fifty years of lunar exploration through telescopic observations, orbital missions, and surface investigations by landers and rovers have provided an extensive dataset on the Moon. Nevertheless, several key scientific questions remain unresolved. These include:the compositional and textural variability of lunar rocks within maria and highlands, including their variation with depth;the physico-chemical properties of the lunar regolith and the processes controlling its formation and evolution under space weathering conditions;the nature and evolution of lunar volcanism, including the diversity of magmatic processes recorded in lunar rocks;the characterization of lunar resources relevant for future exploration and their relationship with surface lithologies;the acquisition and analysis of new lunar samples representative of regions that remain unexplored.VNIR spectroscopy in the 0.3–2.5 µm spectral range represents a powerful tool for investigating the mineralogical composition of the lunar surface. In particular, it enables the identification of major anhydrous mafic silicates—including pyroxenes, plagioclase, and olivine—through the analysis of Fe²⁺ absorption bands near 1 and 2 µm [1-3]. Detailed characterization of these absorption features provides diagnostic information on pyroxene composition and mineral chemistry. Within the same spectral interval, it is also possible to detect Fe-Ti oxides, opaque phases, glasses, and other mineralogical components. Furthermore, VIS–NIR spectroscopy is highly sensitive to physical properties such as grain size and to alteration processes induced by space weathering, including spectral reddening, albedo reduction, and attenuation of absorption-band contrast.A major scientific advantage of LuMISS lies in its capability to investigate the lunar surface at sub-millimetric spatial scales. Such high-resolution observations enable detailed analyses of mineral textures, grain distributions, inclusions, and the relationships among mineralogical phases, providing crucial information on the geological history and evolution of lunar materials.LuMISS is conceptually derived from the Ma_MISS (Mars Multispectral Imager for Subsurface Studies) instrument currently onboard ESA’s ExoMars Rosalind Franklin rover [4]. Building upon the Ma_MISS heritage, LuMISS introduces new developments specifically tailored for lunar exploration. The instrument adopts a modular architecture composed of three main subsystems:an optical head mounted on a robotic arm or directly on a rover/lander structure;a single optical fiber or fiber bundle connecting the optical head to the spectrometer;a spectrometer unit containing the optical elements and detector system.Compared with the Martian application, the lunar environment imposes significantly different operational and thermal constraints. Consequently, the optical head design and deployment concept require substantial adaptation, particularly to withstand extreme lunar temperature variations and to support close-up, high-resolution observations of the regolith and rock samples.Breadboarding and Prototype DevelopmentThe breadboarding phase of the project includes a comprehensive assessment of both scientific and engineering aspects of the instrument. The main activities are:trade-off analyses between scientific objectives, spectrometer configuration, and expected instrument performance;investigation of deployment strategies, including robotic-arm integration and rover-deck mounting configurations;design and optimization of the optical head, including the possible implementation of a focusing mechanism;definition of operational modes for high-resolution hyperspectral imaging;development and assessment of the illumination system;evaluation of system resources, including mass, power consumption, and data volume;characterization of the lunar thermal environment and its impact on instrument design;investigation of thermal-control solutions for stable instrument operation.At the conclusion of the study, the project will define a new optical-head concept for a Ma_MISS-type VNIR spectrometer optimized for close-range investigations of the lunar surface and lunar samples.AcknowledgmentsThis work is supported by the ASI–INAF Agreement n. n. 2025-16-HH (from Sept. 2025 to Aug. 2027)References [1] Pieters, C., Klima, R., & Green, R., 2019. In J. Bishop, J. Bell III, & J. Moersch (Eds.), Remote Compositional Analysis: Techniques for Understanding Spectroscopy, Miner-alogy, and Geochemistry of Planetary Surfaces,pp. 368-392. doi:10.1017/9781316888872.020. [2] Isaacson et al., 2011. Meteoritics and Planetary Sci-ence 46, 228–251. doi:10.1111/j.1945-5100.2010.01148.x . [3] Pieters, C. M., and S. K. Noble, 2016. J. Geophys. Res. Planets, 121, 1865–1884,doi:10.1002/2016JE005128; [4] De Sanctis, M.C. et al. (2017), Astrobiology, 17(6–7)

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