@article{9cc985cd859d4156b40fa44d85785a0a,
title = "The Formation of Terraces on Asteroid (101955) Bennu",
abstract = "The surface of the rubble-pile asteroid (101955) Bennu has been characterized in detail by the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer) mission. By examining global and local digital terrain models, we observed that Bennu possesses terraces, that is, a series of roughly latitude-parallel, step-like slope breaks. These partially circumscribe the poles and extend east-west over several longitudinal quadrants at mid- to high (≥30°) latitudes. The terraces are subtle in amplitude, with heights ranging from 1 to 5 m. They often exhibit back-wasting that results in V-shaped scarps that open downslope in some locations. When boulders >5–10 m are absent at or near a terrace, the steeper portion (the drop) of the terrace lacks rocks, whereas the flatter portion (the bench) of the terrace has accumulations of rocks at its crest. When boulders >5–10 m are present, their steep downslope faces often make up the drop from the terrace crest, and they retain debris upslope, thereby enhancing the terrace structure. A geotechnical stability analysis indicates that Bennu's surface is likely unstable and that surface cohesion is <0.6 Pa. Bennu's terraces strongly resemble scarps generated in laboratory and numerical simulations of a cohesionless granular bed as the slope of the bed increases quasi-statically. We conclude that terraces are probably actively forming on Bennu as its surface slowly fails owing to creep induced by spin acceleration.",
keywords = "Bennu, OSIRIS-REx, asteroids, surface processes",
author = "Barnouin, {O. S.} and Daly, {M. G.} and Seabrook, {J. A.} and Y. Zhang and F. Thuillet and P. Michel and Roberts, {J. H.} and Daly, {R. T.} and Perry, {M. E.} and Susorney, {H. C.M.} and Jawin, {E. R.} and Ballouz, {R. L.} and Walsh, {K. J.} and Sevalia, {M. M.} and {Al Asad}, {M. M.} and Johnson, {C. L.} and Bierhaus, {E. B.} and Gaskell, {R. W.} and Palmer, {E. E.} and J. Weirich and B. Rizk and {Drouet D{\textquoteright}Aubigny}, {C. Y.} and Nolan, {M. C.} and DellaGiustina, {D. N.} and Scheeres, {D. J.} and McMahon, {J. W.} and Connolly, {H. C.} and Richardson, {D. C.} and Wolner, {C. W.V.} and Lauretta, {D. S.}",
note = "Funding Information: This effort was supported by NASA under Contract NNM10AA11C issued through the New Frontiers Program and by the Canadian Space Agency. Y. Zhang acknowledges funding from the Universit{\'e} C{\^o}te d{\textquoteright}Azur “Individual grants for young researchers” program of IDEX JEDI. P. Michel., Y. Zhang, F. Thuillet acknowledge support from the French space agency CNES, from the European Union's Horizon 2020 research and innovation program under grant agreement No 870377 (project NEO-MAPP), and from Academies of Excellence: Complex systems and Space, environment, risk, and resilience, part of the IDEX JEDI of the Universit{\'e} C{\^o}te d{\textquoteright}Azur. The authors would like to thank Tatsuhiro Michikami and one other anonymous reviewer for their comments, which greatly improved this manuscript. Funding Information: This effort was supported by NASA under Contract NNM10AA11C issued through the New Frontiers Program and by the Canadian Space Agency. Y. Zhang acknowledges funding from the Universit{\'e} C{\^o}te d{\textquoteright}Azur “Individual grants for young researchers” program of IDEX JEDI. P. Michel., Y. Zhang, F. Thuillet acknowledge support from the French space agency CNES, from the European Union's Horizon 2020 research and innovation program under grant agreement No 870377 (project NEO‐MAPP), and from Academies of Excellence: Complex systems and Space, environment, risk, and resilience, part of the IDEX JEDI of the Universit{\'e} C{\^o}te d{\textquoteright}Azur. The authors would like to thank Tatsuhiro Michikami and one other anonymous reviewer for their comments, which greatly improved this manuscript. Publisher Copyright: {\textcopyright} 2022. The Authors.",
year = "2022",
month = apr,
doi = "10.1029/2021JE006927",
language = "English (US)",
volume = "127",
journal = "Journal of Geophysical Research: Planets",
issn = "2169-9097",
number = "4",
}