^1,2Marina E. Gemma,³Katherine A. Shirley,¹Timothy D. Glotch,^2,4,5Denton S. Ebel,^2,5,6Kieren T. Howard
Journal of Geopyhsical Research: Planets (in Press) Link to Article [https://doi.org/10.1029/2025JE008963]
¹Department of Geosciences, Stony Brook University, Stony Brook, NY, USA
²Department of Earth and PlanetarySciences, American Museum of Natural History, New York, NY, USA,
³Atmospheric, Oceanic, and Planetary Physics,University of Oxford, Oxford, UK
⁴Lamont‐Doherty Earth Observatory, Columbia University, Palisades, NY, USA
⁵Department of Earth and Environmental Sciences, Graduate Center of the City University of New York, New York, NY,USA
⁶Department of Physical Sciences, Kingsborough College, City University of New York, Brooklyn, NY, USA
Published by arrangement with John Wiley & Sons

aboratory spectral analysis of well-characterized meteorite samples can be employed to more quantitatively analyze asteroid remote sensing data in conjunction with returned extraterrestrial samples. In this work, we examine the combined effects of physical (temperature, particle size) and chemical (petrologic type, metal fraction) variables on visible and near-infrared (VNIR) spectra of ordinary chondrite meteorite powders. Six equilibrated ordinary chondrite meteorite falls were prepared at a variety of particle sizes to capture the spectral diversity associated with asteroid regoliths dominated by various grain sizes. Mineral compositions and abundance were determined from electron microprobe analysis of meteorite thick sections to precisely characterize changes in spectral features due to variations in mineralogy. VNIR spectra of the ordinary chondrites were measured under simulated asteroid surface conditions at a series of temperatures chosen to mimic near-Earth asteroid surfaces. The resulting spectra show minimal variation in both major absorption bands across the simulated near-Earth asteroid temperature regime. Changes in particle size result in variations in band centers and band area ratios for material of the same composition, two key parameters typically used to derive asteroid composition. Unlike previous spectral investigations of ordinary chondrites, we retained the metal fraction in our powders instead of analyzing only the silicate fraction. Metal has a subtle but non-negligible effect on the VNIR spectra of ordinary chondrites. The more petrologically pristine samples from each ordinary chondrite group display relatively weaker absorption bands than their more thermally altered counterparts. The band centers shift to longer wavelengths as grain size and petrologic type increase.