Evidence for widespread hydrated minerals on asteroid (101955) Bennu

• Published in: Nature astronomy Vol. 3; no. 4; pp. 332 - 340
• Main Authors: Hamilton, V. E., Simon, A. A., Christensen, P. R., Reuter, D. C., Clark, B. E., Barucci, M. A., Bowles, N. E., Boynton, W. V., Brucato, J. R., Cloutis, E. A., Connolly, H. C., Donaldson Hanna, K. L., Emery, J. P., Enos, H. L., Fornasier, S., Haberle, C. W., Hanna, R. D., Howell, E. S., Kaplan, H. H., Keller, L. P., Lantz, C., Li, J.-Y., Lim, L. F., McCoy, T. J., Merlin, F., Nolan, M. C., Praet, A., Rozitis, B., Sandford, S. A., Schrader, D. L., Thomas, C. A., Zou, X.-D., Lauretta, D. S.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.04.2019; Nature Publishing Group
• Subjects: 639/33/445/330; 639/33/445/3928; 639/33/445/848; 639/33/445/849; 704/445/848; Asteroids; Astronomy; Astrophysics; Astrophysics and Cosmology; Engineering Sciences; Materials; Minerals; Physics; Physics and Astronomy; Spacecraft; Meteoritics; Mineralogy; Asteroids; Comets and Kuiper belt; Early solar system
• ISSN: 2397-3366; 2397-3366
• DOI: 10.1038/s41550-019-0722-2

Early spectral data from the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission reveal evidence for abundant hydrated minerals on the surface of near-Earth asteroid (101955) Bennu in the form of a near-infrared absorption near 2.7 µm and thermal infrared spectral features that are most similar to those of aqueously altered CM-type carbonaceous chondrites. We observe these spectral features across the surface of Bennu, and there is no evidence of substantial rotational variability at the spatial scales of tens to hundreds of metres observed to date. In the visible and near-infrared (0.4 to 2.4 µm) Bennu’s spectrum appears featureless and with a blue (negative) slope, confirming previous ground-based observations. Bennu may represent a class of objects that could have brought volatiles and organic chemistry to Earth. Signatures of phyllosilicate-like hydrated minerals are widespread on Bennu’s surface, indicating significant aqueous alteration. The lack of spatial variations in the spectra down to the scale of ~100 m indicates both a relatively uniform particle size distribution and a lack of compositional segregation, possibly due to surficial redistribution processes.