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    The pebbles/boulders size distributions on Sais: Rosetta’s final landing site on comet 67P/Churyumov–Gerasimenko

    Pajola, M. and Lucchetti, A. and Fulle, M. and Mottola, S. and Hamm, M. and Da Deppo, V. and Penasa, L. and Kovacs, G. and Massironi, M. and Shi, X. and Tubiana, C. and Güttler, C. and Oklay, N. and Vincent, J.B. and Toth, I. and Davidsson, B. and Naletto, G. and Sierks, H. and Barbieri, C. and Lamy, P.L. and Rodrigo, R. and Koschny, D. and Rickman, H. and Keller, H.U. and Agarwal, J. and A’Hearn, M.F. and Barucci, M.A. and Bertaux, J. L. and Bertini, I. and Cremonese, G. and Debei, S. and De Cecco, M. and Deller, J. and El-Maarry, Mohamed Ramy and Fornasier, S. and Frattin, E. and Gicquel, A. and Groussin, O. and Gutierrez, P. J. and Höfner, S. and Hofmann, M. and Hviid, S.F. and Ip, W.H. and Jorda, L. and Knollenberg, J. and Kramm, J.R. and Kührt, E. and Küppers, M. and Lara, L.M. and Lazzarin, M. and Moreno, J.J. Lopez and Marzari, F. and Michalik, H. and Preusker, F. and Scholten, F. and Thomas, N. (2017) The pebbles/boulders size distributions on Sais: Rosetta’s final landing site on comet 67P/Churyumov–Gerasimenko. Monthly Notices of the Royal Astronomical Society 469 (Suppl_), S636-S645. ISSN 0035-8711.

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    By using the imagery acquired by the Optical, Spectroscopic, and Infrared Remote Imaging System Wide-Angle Camera (OSIRIS WAC), we prepare a high-resolution morphological map of the Rosetta Sais final landing site, characterized by an outcropping consolidated terrain unit, a coarse boulder deposit and a fine particle deposit. Thanks to the 0.014 m resolution images, we derive the pebbles/boulders size-frequency distribution (SFD) of the area in the size range of 0.07–0.70 m. Sais’ SFD is best fitted with a two-segment differential power law: the first segment is in the range 0.07–0.26 m, with an index of −1.7 ± 0.1, while the second is in the range 0.26–0.50 m, with an index of −4.2 +0.4/−0.8. The ‘knee’ of the SFD, located at 0.26 m, is evident both in the coarse and fine deposits. When compared to the Agilkia Rosetta Lander Imaging System images, Sais surface is almost entirely free of the ubiquitous, cm-sized debris blanket observed by Philae. None the less, a similar SFD behaviour of Agilkia, with a steeper distribution above ∼0.3 m, and a flatter trend below that, is observed. The activity evolution of 67P along its orbit provides a coherent scenario of how these deposits were formed. Indeed, different lift pressure values occurring on the two locations and at different heliocentric distances explain the presence of the cm-sized debris blanket on Agilkia observed at 3.0 au inbound. Contrarily, Sais activity after 2.1 au outbound has almost completely eroded the fine deposits fallen during perihelion, resulting in an almost dust-free surface observed at 3.8 au.


    Item Type: Article
    Keyword(s) / Subject(s): methods: data analysis, methods: statistical, comets: individual (67P C–G)
    School: Birkbeck Faculties and Schools > Faculty of Science > School of Natural Sciences
    Depositing User: Administrator
    Date Deposited: 17 Oct 2018 15:52
    Last Modified: 02 Aug 2023 17:45


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