Regional surface morphology of comet 67P/Churyumov-Gerasimenko from Rosetta/OSIRIS images^⋆

¹ Physikalisches Institut, Sidlerstr. 5, University of Bern, 3012 Bern, Switzerland
e-mail: mohammed.elmaarry@space.unibe.ch
² Dipartimento di Geoscienze, University of Padova, via G. Gradenigo 6, 35131 Padova, Italy
³ Centro di Ateneo di Studi ed Attivitá Spaziali, “Giuseppe Colombo” (CISAS), University of Padova, 35122 Padova, Italy
⁴ Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg, 3, 37077 Göttingen, Germany
⁵ INAF–78Osservatorio Astronomico, vicolo dell’Osservatorio 5, 35122 Padova, Italy
⁶ Aix-Marseille Université, CNRS, LAM, UMR 7326, 38 rue Frédéric Joliot-Curie, 13388 Marseille, France
⁷ International Space Science Institute, Hallerstraße 6, 3012 Bern, Switzerland and Centro de Astrobiología, CSIC-INTA, 28850 Torrejón de Ardoz, Madrid, Spain
⁸ Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden and PAS Space Research Center, Bartycka 18A, 00716 Warszawa, Poland
⁹ Scientific Support Office, European Space Agency, 2201 Noordwijk, The Netherlands
¹⁰ Institute for Geophysics and Extraterrestrial Physics, TU Braunschweig, 38106 Braunschweig, Germany
¹¹ Department of Astronomy, University of Maryland, College Park, MD, 20742-2421, USA
¹² LESIA, Obs. de Paris, CNRS, Univ Paris 06, Univ. Paris-Diderot, 5 place J. Janssen, 92195 Meudon, France
¹³ LATMOS, CNRS/UVSQ/IPSL, 11 boulevard d’Alembert, 78280 Guyancourt, France
¹⁴ Centro di Ateneo di Studi ed Attivitá Spaziali, “Giuseppe Colombo” (CISAS), University of Padova, 35122 Padova, Italy
¹⁵ CNR-IFN UOS Padova LUXOR, Via Trasea, 7, 35131 Padova , Italy
¹⁶ Department of Physics and Astronomy, Uppsala University, 75120 Uppsala, Sweden
¹⁷ UNITN, Universitá di Trento, Via Mesiano, 77, 38100 Trento, Italy
¹⁸ Department of Mechanical Engineering – University of Padova, via Venezia 1, 35131 Padova, Italy
¹⁹ INAF–Osservatorio Astronomico, Via Tiepolo 11, 34014 Trieste, Italy
²⁰ Instituto de Astrofísica de Andalucía (CSIC), c/ Glorieta de la Astronomía s/n, 18008 Granada, Spain
²¹ Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstraße 2, 12489 Berlin, Germany
²² National Central University, Graduate Institute of Astronomy, 300 Chung-Da Rd, 32054 Chung-Li, Taiwan
²³ Laboratoire d’Astrophysique de Marseille, 38 rue de Frédéric Joliot-Curie, 13388 Marseille Cedex 13, France
²⁴ Scientific Support Office, European Space Astronomy Centre/ESA, PO Box 78, 28691 Villanueva de la Canada, Madrid, Spain
²⁵ Solar System Exploration Research Virtual Institute, Southwest Research Institute, 1050 Walnut St., Suite 300, Boulder, CO 80302, USA
²⁶ Institut für Datentechnik und Kommunikationsnetze der TU Braunschweig, Hans-Sommer-Str. 66, 38106 Braunschweig, Germany
²⁷ University of Padova, Department of Information Engineering, via Gradenigo 6/B, 35131 Padova, Italy

Received: 23 January 2015
Accepted: 12 May 2015

Abstract

Aims. The OSIRIS camera onboard the Rosetta spacecraft has been acquiring images of the comet 67P/Churyumov-Gerasimenko (67P)’s nucleus at spatial resolutions down to ~0.17 m/px ever since Aug. 2014. These images have yielded unprecedented insight into the morphological diversity of the comet’s surface. This paper presents an overview of the regional morphology of comet 67P.

Methods. We used the images that were acquired at orbits ~20–30 km from the center of the comet to distinguish different regions on the surface and introduce the basic regional nomenclature adopted by all papers in this Rosetta special feature that address the comet’s morphology and surface processes. We used anaglyphs to detect subtle regional and topographical boundaries and images from close orbit (~10 km from the comet’s center) to investigate the fine texture of the surface.

Results. Nineteen regions have currently been defined on the nucleus based on morphological and/or structural boundaries, and they can be grouped into distinctive region types. Consolidated, fractured regions are the most common region type. Some of these regions enclose smooth units that appear to settle in gravitational sinks or topographically low areas. Both comet lobes have a significant portion of their surface covered by a dusty coating that appears to be recently placed and shows signs of mobilization by aeolian-like processes. The dusty coatings cover most of the regions on the surface but are notably absent from a couple of irregular large depressions that show sharp contacts with their surroundings and talus-like deposits in their interiors, which suggests that short-term explosive activity may play a significant role in shaping the comet’s surface in addition to long-term sublimation loss. Finally, the presence of layered brittle units showing signs of mechanical failure predominantly in one of the comet’s lobes can indicate a compositional heterogeneity between the two lobes.