The rocky‐like behavior of cometary landslides on 67P/Churyumov‐Gerasimenko

Alice Lucchetti (1) , Luca Penasa (2) , Maurizio Pajola (1) , Matteo Massironi (3, 2, 1) , Maria Teresa Brunetti (4) , Gabriele Cremonese (1) , Nilda Oklay (5) , Jean‐baptiste Vincent (5) , Stefano Mottola (5) , Sonia Fornasier (6) , Holger Sierks (7) , Giampiero Naletto (2, 8, 9) , Philippe Lamy (10) , Rafael Rodrigo (11, 12) , Detlef Koschny (13) , Björn Davidsson (14) , Cesare Barbieri (8) , Maria Antonietta Barucci (6) , Jean-Loup Bertaux (10) , Ivano Bertini (8) , Dennis Bodewits (15) , Pamela Cambianica (2) , Vania Da Deppo (16) , Stefano Debei (17) , Mariolino De Cecco (18) , Jacob Deller (7) , Sabrina Ferrari (2) , Francesca Ferri (2) , Marco Franceschi (3) , Marco Fulle (19) , Pedro A Gutiérrez (20) , Carsten Güttler (7) , Wing‐h. Ip (21, 22) , Uwe Keller (23, 5) , Luisa M. Lara (20) , Monica Lazzarin (8) , Jose Lopez Moreno (20) , Francesco Marzari (8) , Cécilia Tubiana (7)

1 OAPD - INAF - Osservatorio Astronomico di Padova
2 CISAS - Centro di Ateneo di Studi e Attività Spaziali “Giuseppe Colombo”
3 Dipartimento di Geoscienze [Padova]
4 IRPI - Research Institute for Geo-hydrological Protection [Perugia]
5 DLR Institut für Planetenforschung
6 LESIA (UMR_8109) - Laboratoire d'études spatiales et d'instrumentation en astrophysique
7 MPS - Max-Planck-Institut für Sonnensystemforschung
8 Dipartimento di Fisica e Astronomia "Galileo Galilei"
9 IFN - CNR Istituto di Fotonica e Nanotecnologie [Padova]
10 PLANETO - LATMOS
11 CAB - Centro de Astrobiologia [Madrid]
12 ISSI - International Space Science Institute [Bern]
13 ESTEC - European Space Research and Technology Centre
14 JPL - Jet Propulsion Laboratory
15 AU - Auburn University
16 IFN - CNR Institute for Photonics and Nanotechnologies
17 Department of Industrial Engineering [Padova]
18 University of Trento [Trento]
19 OAT - INAF - Osservatorio Astronomico di Trieste
20 IAA - Instituto de Astrofísica de Andalucía
21 IANCU - Institute of Astronomy [Taiwan]
22 SSI - Space Science Institute [Macau]
23 IGEP - Institut für Geophysik und Extraterrestrische Physik [Braunschweig]

Landslides have been identified on several Solar System bodies and different mechanisms have been proposed to explain their runout length. We analyse images from the Rosetta mission and report the global characterisation of such features on comet 67P/Churyumov‐Gerasimenko's surface. By assuming the height to runout length as an approximation for the friction coefficient of landslide material, we find that on comet 67P, this ratio falls between 0.50 and 0.97. Such unexpected high values reveal a rocky‐type mechanical behaviour that is much more akin to Earth dry landslides than to icy satellites' mass movements. This behaviour indicates that 67P and likely comets in general are characterised by consolidated materials possibly rejecting the idea that they are fluffy aggregates. The variability of the runout length among 67P landslides can be attributed to the different volatile content located in the top few meters of the cometary crust, which can drive the mass movement.

Domains: Sciences of the Universe [physics]

Alice Lucchetti, Luca Penasa, Maurizio Pajola, Matteo Massironi, Maria Teresa Brunetti, et al.. The rocky‐like behavior of cometary landslides on 67P/Churyumov‐Gerasimenko. Geophysical Research Letters, 2019, 46 (24), pp.14336-14346. ⟨10.1029/2019GL085132⟩. ⟨insu-02418689⟩