Lunar Rock and Mineral Characterization Consortium (LRMCC): Groundwork for Lunar Science and Exploration

A number of hyperspectral instruments (M3, SIR-2, HySI on Chandrayaan-1, Spectral Profiler on Kaguya), which enable detailed characterization of surface mineralogy, are currently in operation or soon to be launched on missions to the Moon. Such instruments provide the highest spatial resolution compositional data of the lunar surface. Mineralogical characterization with reflectance spectrometers relies in large part on a high quality library of ground truth measurements. While the fundamental, diagnostic mineral absorption bands and their variation across the visible to near-infrared wavelengths are understood and based in mineral physics, the diversity of combinations and physical forms of minerals found in a natural environment is large and can affect the observed spectra significantly. The goal of the LRMCC is to examine the mineral components of lunar rocks, which are unaffected by the complicating process of space weathering. Coordinated analyses of the mineralogy, petrology, and reflectance spectra of four lunar basalt samples and associated mineral separates will form the core of a spectral library of well-characterized lunar materials, which will enable detailed exploration of geological processes across the lunar surface.

The LRMCC has analyzed a suite of lunar basalt samples (15058, 15555, 70017, 70035) prepared specifically for coordinated analyses. Samples were allocated as slabs and paired thin sections. Detailed geochemical data were obtained from analyses of the thin sections, and the slabs were used to prepare high-quality mineral separates. Subsets of these mineral separates were prepared as grain mounts used to validate and document the compositional range of the minerals. The mineral separates and bulk samples were crushed to a series of standard grain size ranges, and their reflectance spectra measured in the visible to near infrared (bidirectional) and mid-infrared (FTIR) in the RELAB at Brown University. Initial results of these coordinated analyses will be presented.