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    Tensile strength of 67P/Churyumov–Gerasimenko nucleus material from overhangs

    Attree, N. and Groussin, O. and Jorda, L. and Nébouy, D. and Thomas, N. and Brouet, Y. and Kührt, E. and Preusker, F. and Scholten, F. and Knollenberg, J. and Hartogh, P. and Sierks, H. and Barbieri, C. and Lamy, P. and Rodrigo, R. and Koschny, D. and Rickman, H. and Keller, H.U. and A’Hearn, M.F. and Auger, A.-T. and Barucci, M.A. and Bertaux, J.-L. and Bertini, I. and Bodewits, D. and Boudreault, S. and Cremonese, G. and Da Deppo, V. and Davidsson, B. and Debei, S. and De Cecco, M. and Deller, J. and El-Maarry, Mohamed Ramy and Fornasier, S. and Fulle, M. and Gutiérrez, P. J. and Güttler, C. and Hviid, S. and Ip, W.-H. and Kovacs, G. and Kramm, J. R. and Küppers, M. and Lara, L.M. and Lazzarin, M. and Lopez Moreno, J. J. and Lowry, S. and Marchi, S. and Marzari, F. and Mottola, S. and Naletto, G. and Oklay, N. and Pajola, M. and Toth, I. and Tubiana, C. and Vincent, J.-B. and Shi, X. (2018) Tensile strength of 67P/Churyumov–Gerasimenko nucleus material from overhangs. Astronomy & Astrophysics 611 , A33. ISSN 0004-6361.

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    Abstract

    We directly measured twenty overhanging cliffs on the surface of comet 67P/Churyumov–Gerasimenko extracted from the latest shape model and estimated the minimum tensile strengths needed to support them against collapse under the comet’s gravity. We find extremely low strengths of around 1 Pa or less (1 to 5 Pa, when scaled to a metre length). The presence of eroded material at the base of most overhangs, as well as the observed collapse of two features andthe implied previous collapse of another, suggests that they are prone to failure and that the true material strengths are close to these lower limits (although we only consider static stresses and not dynamic stress from, for example, cometary activity). Thus, a tensile strength of a few pascals is a good approximation for the tensile strength of the 67P nucleus material, which is in agreement with previous work. We find no particular trends in overhang properties either with size over the ~10–100 m range studied here or location on the nucleus. There are no obvious differences, in terms of strength, height or evidence of collapse, between the populations of overhangs on the two cometary lobes, suggesting that 67P is relatively homogenous in terms of tensile strength. Low material strengths are supportive of cometary formation as a primordial rubble pile or by collisional fragmentation of a small body (tens of km).

    Metadata

    Item Type: Article
    Additional Information: Erratum at https://doi.org/10.1051/0004-6361/201732155e
    Keyword(s) / Subject(s): comets: general, comets: individual, Churyumov–Gerasimenko, Methods: observational
    School: Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences
    Depositing User: Administrator
    Date Deposited: 17 Oct 2018 15:23
    Last Modified: 29 Jul 2019 08:30
    URI: http://eprints.bbk.ac.uk/id/eprint/24728

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