Asteroid (101955) Bennu's weak boulders and thermally anomalous equator


B. Rozitis, The Open University
A. J. Ryan, The University of Arizona
J. P. Emery, Northern Arizona University
P. R. Christensen, School of Earth and Space Exploration
V. E. Hamilton, Space Science and Engineering Division
A. A. Simon, NASA Goddard Space Flight Center
D. C. Reuter, NASA Goddard Space Flight Center
M. Al Asad, The University of British Columbia
R. L. Ballouz, The University of Arizona
J. L. Bandfield, Space Science Institute
O. S. Barnouin, Johns Hopkins University Applied Physics Laboratory
C. A. Bennett, The University of Arizona
M. Bernacki, Centre de Mise en Forme des Materiaux
K. N. Burke, The University of Arizona
S. Cambioni, The University of Arizona
B. E. Clark, Ithaca College
M. G. Daly, York University, Centre For Research in Earth and Space Science
M. Delbo, Observatoire de la Côte d'Azur
D. N. DellaGiustina, The University of Arizona
C. M. Elder, Jet Propulsion Laboratory
R. D. Hanna, Jackson School of Geosciences
C. W. Haberle, School of Earth and Space Exploration
E. S. Howell, The University of Arizona
D. R. Golish, The University of Arizona
E. R. Jawin, Smithsonian National Museum of Natural History
H. H. Kaplan, NASA Goddard Space Flight Center
L. F. Lim, NASA Goddard Space Flight Center
J. L. Molaro, Planetary Science Institute
D. Pino Munoz, Centre de Mise en Forme des Materiaux
M. C. Nolan, The University of Arizona
B. Rizk, The University of Arizona
M. A. Siegler, Planetary Science Institute
H. C.M. Susorney, University of Bristol

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© 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC). Thermal inertia and surface roughness are proxies for the physical characteristics of planetary surfaces. Global maps of these two properties distinguish the boulder population on near-Earth asteroid (NEA) (101955) Bennu into two types that differ in strength, and both have lower thermal inertia than expected for boulders and meteorites. Neither has strongly temperature-dependent thermal properties. The weaker boulder type probably would not survive atmospheric entry and thus may not be represented in the meteorite collection. The maps also show a high-thermal inertia band at Bennu's equator, which might be explained by processes such as compaction or strength sorting during mass movement, but these explanations are not wholly consistent with other data. Our findings imply that other C-complex NEAs likely have boulders similar to those on Bennu rather than finer-particulate regoliths. A tentative correlation between albedo and thermal inertia of C-complex NEAs may be due to relative abundances of boulder types.

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Science Advances

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