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Nature. 2015 Jul 2;523(7558):63-6. doi: 10.1038/nature14564.

Large heterogeneities in comet 67P as revealed by active pits from sinkhole collapse.

Author information

1
Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany.
2
University of Maryland, Department of Astronomy, College Park, Maryland 20742-2421, USA.
3
Scientific Support Office, European Space Research and Technology Centre/ESA, Keplerlaan 1, Postbus 299, 2201 AZ Noordwijk ZH, The Netherlands.
4
University of Padova, Department of Physics and Astronomy, Vicolo dell'Osservatorio 3, 35122 Padova, Italy.
5
Laboratoire d'Astrophysique de Marseille, UMR 7326, CNRS and Aix Marseille Université, 13388 Marseille Cedex 13, France.
6
1] Centro de Astrobiologia, CSIC-INTA, 28850 Torrejon de Ardoz, Madrid, Spain [2] International Space Science Institute, Hallerstraße 6, 3012 Bern, Switzerland.
7
1] Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden [2] PAS Space Research Center, Bartycka 18A, 00716 Warszawa, Poland.
8
Institut für Geophysik und extraterrestrische Physik (IGEP), Technische Universität Braunschweig, Mendelssohnstraße 3, 38106 Braunschweig, Germany.
9
1] University of Maryland, Department of Astronomy, College Park, Maryland 20742-2421, USA [2] Akademie der Wissenschaften zu Göttingen and Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany.
10
LESIA-Observatoire de Paris, CNRS, Université Pierre et Marie Curie, Universite Paris Diderot, 5 place Jules Janssen, 92195 Meudon, France.
11
LATMOS, CNRS/UVSQ/IPSL, 11 boulevard d'Alembert, 78280 Guyancourt, France.
12
Centro di Ateneo di Studi ed Attività Spaziali "Giuseppe Colombo" (CISAS), University of Padova, via Venezia 15, 35131 Padova, Italy.
13
INAF, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy.
14
CNR-IFN UOS Padova LUXOR, via Trasea 7, 35131 Padova, Italy.
15
Centro de Astrobiologia, CSIC-INTA, 28850 Torrejon de Ardoz, Madrid, Spain.
16
Department of Industrial Engineering, University of Padova, via Venezia 1, 35131 Padova, Italy.
17
University of Trento, via Mesiano 77, 38100 Trento, Italy.
18
Physikalisches Institut der Universität Bern, Sidlerstraße 5, 3012 Bern, Switzerland.
19
INAF Osservatorio Astronomico, via Tiepolo 11, 34014 Trieste, Italy.
20
Planetary Science Institute, Tucson, Arizona 85719, USA.
21
Instituto de Astrofisica de Andalucia (CSIC), Glorieta de la Astronomìa s/n, 18008 Granada, Spain.
22
Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstraße 2, 12489 Berlin, Germany.
23
National Central University, Graduate Institute of Astronomy, 300 Chung-Da Rd, Chung-Li 32054, Taiwan.
24
Operations Department, European Space Astronomy Centre/ESA, PO Box 78, 28691 Villanueva de la Canada, Madrid, Spain.
25
The University of Kent, School of Physical Sciences, Canterbury, Kent CT2 7NZ, UK.
26
University of Padova, Deptartment of Physics and Astronomy, via Marzolo 8, 35131 Padova, Italy.
27
Solar System Exploration Research Virtual Institute, Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, Colorado 80302, USA.
28
Dipartimento di Geoscienze, University of Padova, via Giovanni Gradenigo 6, 35131 Padova, Italy.
29
Institut für Datentechnik und Kommunikationsnetze der Technische Universität Braunschweig, Hans-Sommer-Straße 66, 38106 Braunschweig, Germany.
30
1] Centro di Ateneo di Studi ed Attività Spaziali "Giuseppe Colombo" (CISAS), University of Padova, via Venezia 15, 35131 Padova, Italy [2] CNR-IFN UOS Padova LUXOR, via Trasea 7, 35131 Padova, Italy [3] University of Padova, Department of Information Engineering, via Gradenigo 6/B, 35131 Padova, Italy.
31
Konkoly Observatory of the Hungarian Academy of Sciences, PO Box 67, 1525 Budapest, Hungary.

Abstract

Pits have been observed on many cometary nuclei mapped by spacecraft. It has been argued that cometary pits are a signature of endogenic activity, rather than impact craters such as those on planetary and asteroid surfaces. Impact experiments and models cannot reproduce the shapes of most of the observed cometary pits, and the predicted collision rates imply that few of the pits are related to impacts. Alternative mechanisms like explosive activity have been suggested, but the driving process remains unknown. Here we report that pits on comet 67P/Churyumov-Gerasimenko are active, and probably created by a sinkhole process, possibly accompanied by outbursts. We argue that after formation, pits expand slowly in diameter, owing to sublimation-driven retreat of the walls. Therefore, pits characterize how eroded the surface is: a fresh cometary surface will have a ragged structure with many pits, while an evolved surface will look smoother. The size and spatial distribution of pits imply that large heterogeneities exist in the physical, structural or compositional properties of the first few hundred metres below the current nucleus surface.

PMID:
26135448
DOI:
10.1038/nature14564

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