TY - JOUR
T1 - In search of Bennu analogs
T2 - Hapke modeling of meteorite mixtures
AU - Merlin, F.
AU - Deshapriya, J. D.P.
AU - Fornasier, S.
AU - Barucci, M. A.
AU - Praet, A.
AU - Hasselmann, P. H.
AU - Clark, B. E.
AU - Hamilton, V. E.
AU - Simon, A. A.
AU - Reuter, D. C.
AU - Zou, X. D.
AU - Li, J. Y.
AU - Schrader, D. L.
AU - Lauretta, D. S.
N1 - Funding Information:
cA knolw edgemen. This material is based on work supported by NASA under Contract NNM10AA11C issued through the New Frontiers Program. F.M., M.A.B., P.H., A.P., J.D.P.D. and S.F. acknowledge funding support from CNES. We thank P. Beck for his helpful support in making use of the absorbance data and A. Raponi for his comments to improve the quality of this paper. We are grateful to the entire OSIRIS-REx Team for making the encounter with Bennu possible.
Publisher Copyright:
© F. Merlin et al. 2021.
PY - 2021/4/1
Y1 - 2021/4/1
N2 - Context. The OSIRIS-REx Visible and InfraRed Spectrometer onboard the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer spacecraft obtained many spectra from the surface of the near-Earth asteroid (101955) Bennu, enabling the characterization of this primitive small body. Bennu is spectrally similar to the hydrated carbonaceous chondrites (CCs), but questions remain as to which CCs, or combinations thereof, offer the best analogy to its surface. Aims. We aim to understand in more detail the composition and particle size of Bennu's surface by refining the relationship between this asteroid and various CC meteorites. Methods. We used published absorbance and reflectance data to identify new optical constants for various CC meteorites measured in the laboratory at different temperatures. We then used the Hapke model to randomly generate 1000 synthetic spectra in order to find the combinations of these potential meteoritic analogs that best reproduce the spectral features of the asteroid. Results. Our investigations suggest that the surface of Bennu, though visibly dominated by boulders and coarse rubble, is covered by small particles (tens to a few hundreds of μm) and that possibly dust or powder covers the larger rocks. We further find that the surface is best modeled using a mixture of heated CM, C2-ungrouped, and, to some extent, CI materials. Conclusions. Bennu is best approximated spectrally by a combination of CC materials and may not fall into an existing CC group.
AB - Context. The OSIRIS-REx Visible and InfraRed Spectrometer onboard the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer spacecraft obtained many spectra from the surface of the near-Earth asteroid (101955) Bennu, enabling the characterization of this primitive small body. Bennu is spectrally similar to the hydrated carbonaceous chondrites (CCs), but questions remain as to which CCs, or combinations thereof, offer the best analogy to its surface. Aims. We aim to understand in more detail the composition and particle size of Bennu's surface by refining the relationship between this asteroid and various CC meteorites. Methods. We used published absorbance and reflectance data to identify new optical constants for various CC meteorites measured in the laboratory at different temperatures. We then used the Hapke model to randomly generate 1000 synthetic spectra in order to find the combinations of these potential meteoritic analogs that best reproduce the spectral features of the asteroid. Results. Our investigations suggest that the surface of Bennu, though visibly dominated by boulders and coarse rubble, is covered by small particles (tens to a few hundreds of μm) and that possibly dust or powder covers the larger rocks. We further find that the surface is best modeled using a mixture of heated CM, C2-ungrouped, and, to some extent, CI materials. Conclusions. Bennu is best approximated spectrally by a combination of CC materials and may not fall into an existing CC group.
KW - Methods: data analysis
KW - Methods: observational
KW - Minor planets, asteroids: individual: (101955) Bennu
KW - Techniques: spectroscopic
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U2 - 10.1051/0004-6361/202140343
DO - 10.1051/0004-6361/202140343
M3 - Article
AN - SCOPUS:85103624067
VL - 648
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
SN - 0004-6361
M1 - A88
ER -