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

Jean-Baptiste Vincent (1) , Dennis Bodewits (2) , Sébastien Besse (3) , Holger Sierks (1) , Cesare Barbieri (4) , Philippe Lamy (5) , Rafael Rodrigo (6, 7) , Detlef Koschny (3) , Hans Rickman (8, 9) , Horst Uwe Keller (10) , Jessica Agarwal (1) , Michael F. A'Hearn (2) , Anne-Thérèse Auger (5) , M. Antonella Barucci (11) , Jean-Loup Bertaux (12) , Ivano Bertini (13) , Claire Capanna (5) , Gabriele Cremonese (14) , Vania da Deppo (15) , Björn Davidsson (7) , Stefano Debei (16) , Mariolino de Cecco (17) , Mohamed Ramy El-Maarry (18) , Francesca Ferri (13) , Sonia Fornasier (11) , Marco Fulle (19) , Robert Gaskell (20) , Lorenza Giacomini (13) , Olivier Groussin (5) , Aurélie Guilbert-Lepoutre (2) , P. Gutierrez-Marques (1) , Pedro J. Gutiérrez (21) , Carsten Güttler (1) , Nick Hoekzema (1) , Sebastian Höfner (1) , Stubbe F. Hviid (22) , Wing-Huen Ip (23) , Laurent Jorda (5) , Jörg Knollenberg (22) , Gabor Kovacs (1) , Rainer Kramm (1) , Ekkehard Kührt (22) , Michael Küppers (24) , Fiorangela La Forgia (4) , Luisa M. Lara (21) , Monica Lazzarin (4) , Vicky Lee (25) , Cédric Leyrat (11) , Zhong-Yi Lin (23) , Josè J. Lopez Moreno (21) , Stephen Lowry (26) , Sara Magrin (4) , Lucie Maquet (24) , Simone Marchi (27) , Francesco Marzari (4) , Matteo Massironi (28) , Harald Michalik (29) , Richard Moissl (24) , Stefano Mottola (22) , Giampiero Naletto (13, 15) , Nilda Oklay (1) , Maurizio Pajola (13) , Frank Preusker (22) , Frank Scholten (22) , Nicolas Thomas (18) , Imre Toth (30) , Cecilia Tubiana (1)

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

Pits have been observed on many cometary nuclei mapped by spacecraft1, 2, 3, 4. 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 experiments5, 6 and models7, 8 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 impacts8, 9. Alternative mechanisms like explosive activity10 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.

Domains: Earth and Planetary Astrophysics [astro-ph.EP]

Jean-Baptiste Vincent, Dennis Bodewits, Sébastien Besse, Holger Sierks, Cesare Barbieri, et al.. Large heterogeneities in comet 67P as revealed by active pits from sinkhole collapse. Nature, 2015, 523 (7558), pp.63-66. ⟨10.1038/nature14564⟩. ⟨insu-01176031⟩