Quantitative mineral analysis of (99942) Apophis using reflectance spectroscopy |
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| Authors: | PengYue Wang Edward Cloutis XiaoPing Zhang Ye Su YunZhao Wu |
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| Institution: | 1. State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau, China;2. Department of Geography, University of Winnipeg, Winnipeg, Canada;3. State Key Laboratory of Lunar and Planetary Sciences, Macau University of Science and Technology, Macau, China
Center for Excellence in Comparative Planetology, Chinese Academy of Science, Hefei, China |
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| Abstract: | The impact threat of some near-Earth Asteroids (NEAs) drives our need to understand their mineral compositions. Quantitative mineral abundances based on reflectance spectroscopy are of great significance for studying the compositions of NEAs. In this study, we constrained the surface mineralogy of (99942) Apophis based on multiple diagnostic spectral parameters. The influence of non-mineral component factors (e.g., space weathering, phase angle, and surface temperature) on diagnostic spectral parameters was evaluated. We established the connection between Apophis and corresponding meteorite analog. Our results show that the abundances of olivine and pyroxene on the surface of Apophis are 53.4 ± 6 wt% and 35.6 ± 2 wt%, respectively. The 1 μm band width is basically unaffected by phase-angle changes and is less affected by temperature variations. Low temperature has more obvious effects on the 1.25/1 μm band depth ratio (BDR 1.25) based on the present data. When the phase angle ranges from 60° to 120°, the BDR 1.25 changes significantly with the increase or decrease of phase angle. In terms of spectral characteristics, the best meteorite analog of Apophis is LL chondrite, confirming earlier interpretations. Mineral analyses based on multiple diagnostic spectral parameters provide more consistent results. Knowledge of the surface compositions of Apophis can also inform optimum or possible defense strategies for it and other NEAs. |
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