205-3 Crystallography on Mars and Next-Generation Mineralogical Instruments for Planetary Exploration

Session: MSA 2025 Awards Lectures and Presidential Address

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Minerals are the key to unlocking the geologic history of any planetary body. The mineral assemblage of a rock reveals information about physical processes, like volcanism or tectonism, chemical processes, like aqueous alteration, and biological processes. Crystallographic data can provide important details about these processes through analyses of mineral structures and crystal chemistry. The Chemistry and Mineralogy (CheMin) X-ray diffractometer (XRD) and X-ray fluorescence (XRF) spectrometer on the Mars Science Laboratory Curiosity rover is the only planetary instrument capable of collecting crystallographic information on whole-rock mineral assemblages. Since Curiosity’s landing in Gale crater in 2012, CheMin has analyzed powder from 43 drill holes into sedimentary rocks and three samples of modern, eolian sand. Crystallographic information from XRD enables discrimination between different SiO2 polymorphs, identification of mineral hydration states, analysis of crystal chemistry and elemental substitution, and evaluation of crystallite size. When combined with sedimentological information, mineralogical data from CheMin demonstrate that Gale crater was the site of lakes, rivers, and eolian dunes ~3.5 billion years ago and that the salinity, temperature, and redox conditions of the surface and ground waters changed over space and time. Mineralogical data are, therefore, critical to evaluating ancient and modern planetary habitability and in the search for life beyond Earth. Over the past 10 years, new versions of the CheMin instrument and offshoots based on its geometry have been developed for flight on missions to any solid planetary body. New versions of CheMin use less power, collect data over shorter periods of time, and have improved angular resolution. An X-ray computed tomography instrument is being developed using the CheMin geometry that would provide micromorphological and geochemical data that are complementary to XRD data. In addition to science-driven missions, these mineralogical instruments could be used to identify resources and enable human exploration of the solar system.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-6226

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