^1,2C. J. Gimar,^2,1,3U. Raut,^2,3M. P. Poston,⁴A. Stevanovic,^5,2S. Protopapa,³T. K. Greathouse,^2,1,3K. D. Retherford,^2,3J. M. Friday,^2,3J. T. Grimes
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2022JE007508]
¹Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX, 78249 United States
²Center for Laboratory Astrophysics and Space Science Experiments (CLASSE), Space Science and Engineering Division, Southwest Research Institute, San Antonio, TX, 78238 United States
³Space Science and Engineering Division, Southwest Research Institute, San Antonio, TX, 78238 United States
⁴Kleberg Advanced Microscopy Center, University of Texas at San Antonio, San Antonio, TX, 78249 United States
⁵Department of Space Studies, Southwest Research Institute, Boulder, CO, 80302 USA
Published by arrangement with John Wiley & Sons

We have characterized the far-ultraviolet (FUV) spectro-photometric response of lunar soil simulants JSC-1A and LMS-1, reporting notable differences from our previous results for Apollo soil 10084 (Raut et al., 2018). While JSC-1A and LMS-1 were designed to emulate the geotechnical and compositional properties of a low-Ti and high-Ti mare soil respectively, these terrestrial simulants lack “space weathering” attributes such as the nanophase iron present in the weathered rims of Apollo grains and glassy agglutinates. Photometric analyses of the JSC-1A phase curves reveal a ∼ 3-4 fold increase in single scattering albedo (SSA) and a forward scattering behavior compared to 10084. LMS-1 is shown to have SSA nearly twice that of 10084 and a near isotropic reflectance. Additionally, both JSC-1A and LMS-1 spectra present a blue slope in the FUV, with the JSC-1A slope ∼ 10× larger than that reported for the 10084 soil. Our analyses imply that low-Ti content, corroborated using energy dispersive x-ray spectroscopy, correlates to brighter FUV reflectance and a greater spectral blue slope for JSC-1A, while space weathering components likely contribute to the backscattering of FUV light by the Apollo soil relative to both simulants. Further work with an extended set of Apollo soils is warranted to deconvolute the relative contributions of weathering and composition to their FUV spectro-photometric response.