Mapping Phyllosilicates on the Asteroid Bennu Using Thermal Emission Spectra and Machine Learning Model Applications

Bennu, the target of the OSIRIS‐REx mission, is an asteroid with compositions analogous to low petrologic type CI, CM, CR, and/or ungrouped carbonaceous chondrites. Asteroids like Bennu provide information about the building blocks of the early Solar System. Analysis of the mid‐infrared remote sensing data informs mineral quantification. We apply a phyllosilicate specific model, developed by Breitenfeld et al. (2021, https://doi.org/10.1029/2021je007035) that distinguishes between Mg and Fe serpentines, to Baseball Diamond 1 (BBD1), equatorial station 3 (EQ3), and touch‐and‐go OSIRIS‐REx thermal emission spectrometer data. The average total phyllosilicate predictions are 73 (BBD1) and 72 vol% (EQ3). We observe higher Fe‐cronstedtite and lower Mg‐rich serpentine content in the equatorial region of Bennu than average. Mid‐infrared spectral variability may be explained by sorting effects through mass movement.

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