Fractures on comet 67P/Churyumov-Gerasimenko observed by Rosetta/OSIRIS

M.R. El-Maarry (1) , N. Thomas (1) , A. Gracia-Berná (1) , R. Marschall (1) , A-T. Auger (2) , O. Groussin (2) , S. Mottola (3) , M. Pajola (4) , M. Massironi (4, 5) , S. Marchi (6) , S. Höfner (7) , F. Preusker (3) , F. Scholten (3) , L. Jorda (2) , Ekkehard Kührt (3) , H. U. Keller (3, 8) , H. Sierks (7) , Michael F. A'Hearn (9) , C. Barbieri (10) , M. A. Barucci (11) , Jean-Loup Bertaux (12) , I. Bertini (4) , Gabriele Cremonese (13) , V. da Deppo (14) , B. Davidsson (15) , S. Debei (16) , M. de Cecco (17) , J. Deller (7) , C. Güttler (7) , S. Fornasier (11) , M. Fulle (18) , P. J. Gutierrez (19) , M. Hofmann (7) , S. F. Hviid (3) , W-H. Ip (20) , J. Knollenberg (3) , D. Koschny (21) , G. Kovacs (7) , J.-R. Kramm (7) , M. Küppers (22) , P. L. Lamy (2) , L. M. Lara (19) , M. Lazzarin (10) , J. J. Lopez Moreno (19) , F. Marzari (10) , H. Michalik (23) , G. Naletto (4, 14, 16) , N. Oklay (7) , A. Pommerol (1) , H. Rickman (15, 24) , R. Rodrigo (25, 26) , C. Tubiana (7) , J-B. Vincent (7)

1 Physikalisches Institut [Bern]
2 LAM - Laboratoire d'Astrophysique de Marseille
3 DLR Institute of Planetary Research
4 CISAS - Centro di Ateneo di Studi e Attività Spaziali “Giuseppe Colombo”
5 Dipartimento di Geoscienze [Padova]
6 SSERVI - Solar System Exploration Research Virtual Institute
7 MPS - Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research
8 IGEP - Institut für Geophysik und Extraterrestrische Physik [Braunschweig]
9 Department of Astronomy [College Park]
10 Dipartimento di Fisica e Astronomia "Galileo Galilei"
11 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
12 PLANETO - LATMOS
13 OAPD - INAF - Osservatorio Astronomico di Padova
14 IFN - CNR Institute for Photonics and Nanotechnologies
15 Department of Physics and Astronomy [Uppsala]
16 Department of Industrial Engineering [Padova]
17 UNITN - Università degli Studi di Trento = University of Trento
18 OAT - INAF - Osservatorio Astronomico di Trieste
19 IAA - Instituto de Astrofísica de Andalucía
20 IANCU - Institute of Astronomy [Taiwan]
21 RSSD - Research and Scientific Support Department, ESTEC
22 Operations Department (ESAC)
23 Institut für Datentechnik und Kommunikationsnetze
24 CBK - Space Research Centre of Polish Academy of Sciences
25 CAB - Centro de Astrobiologia [Madrid]
26 ISSI - International Space Science Institute [Bern]

The OSIRIS experiment onboard the Rosetta spacecraft currently orbiting comet 67P/Churyumov-Gerasimenko has yielded unprecedented views of a comet's nucleus. We present here the first ever observations of meter-scale fractures on the surface of a comet. Some of these fractures form polygonal networks. We present an initial assessment of their morphology, topology, and regional distribution. Fractures are ubiquitous on the surface of the comet's nucleus. Furthermore, they occur in various settings and show different topologies suggesting numerous formation mechanisms, which include thermal insolation weathering, orbital-induced stresses, and possibly seasonal thermal contraction. However, we conclude that thermal insolation weathering is responsible for creating most of the observed fractures based on their morphology and setting in addition to thermal models that indicate diurnal temperature ranges exceeding 200 K and thermal gradients of ~15 K/min at perihelion are possible. Finally, we suggest that fractures could be a facilitator in surface evolution and long-term erosion.

Mots clés: Fractures; Comets; OSIRIS; Comet 67P; Rosetta

Domaines: Planétologie et astrophysique de la terre [astro-ph.EP]

M.R. El-Maarry, N. Thomas, A. Gracia-Berná, R. Marschall, A-T. Auger, et al.. Fractures on comet 67P/Churyumov-Gerasimenko observed by Rosetta/OSIRIS. Geophysical Research Letters, 2015, 42 (13), pp.5170-5178. ⟨10.1002/2015GL064500⟩. ⟨insu-01176074⟩