The pristine interior of comet 67P revealed by the combined Aswan outburst and cliff collapse - INSU - Institut national des sciences de l'Univers Access content directly
Journal Articles Nature Astronomy Year : 2017

The pristine interior of comet 67P revealed by the combined Aswan outburst and cliff collapse

1 ARC - NASA Ames Research Center
2 CISAS - Centro di Ateneo di Studi e Attività Spaziali “Giuseppe Colombo”
3 MPS - Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research
4 DLR Institut für Planetenforschung
5 IFN - CNR Institute for Photonics and Nanotechnologies
6 DEI - Department of Information Engineering [Padova]
7 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
8 School of Physical Sciences [Canterbury]
9 LAM - Laboratoire d'Astrophysique de Marseille
10 CAB - Centro de Astrobiologia [Madrid]
11 ISSI - International Space Science Institute [Bern]
12 ESTEC - European Space Research and Technology Centre
13 Department of Physics and Astronomy [Uppsala]
14 CBK - Space Research Centre of Polish Academy of Sciences
15 IGEP - Institut für Geophysik und Extraterrestrische Physik [Braunschweig]
16 Department of Astronomy [College Park]
17 PLANETO - LATMOS
18 Operations Department (ESAC)
19 OAPD - INAF - Osservatorio Astronomico di Padova
20 Department of Industrial Engineering [Padova]
21 UNITN - Università degli Studi di Trento = University of Trento
22 LASP - Laboratory for Atmospheric and Space Physics [Boulder]
23 Physikalisches Institut [Bern]
24 OAT - INAF - Osservatorio Astronomico di Trieste
25 IAA - Instituto de Astrofísica de Andalucía
26 SSI - Space Science Institute [Macau]
27 Dipartimento di Fisica e Astronomia "Galileo Galilei"
28 Dipartimento di Geoscienze [Padova]
29 Konkoly Observatory
30 DICAM - Department of Civil Chemical Environmental and Materials Engineering [Bologna]
Jean-Loup Bertaux
  • Function : Author
  • PersonId : 914210
Wing-Huen Ip
Laurent Jorda
Michael Küppers
A. Lucchetti
Nicolas Thomas
Imre Toth
  • Function : Author

Abstract

Outbursts occur commonly on comets1 with different frequencies and scales2,3. Despite multiple observations suggesting various triggering processes4,5, the driving mechanism of such outbursts is still poorly understood. Landslides have been invoked6 to explain some outbursts on comet 103P/Hartley 2, although the process required a pre-existing dust layer on the verge of failure. The Rosetta mission observed several outbursts from its target comet 67P/Churyumov–Gerasimenko, which were attributed to dust generated by the crumbling of materials from collapsing cliffs7,8. However, none of the aforementioned works included definitive evidence that landslides occur on comets. Amongst the many features observed by Rosetta on the nucleus of the comet, one peculiar fracture, 70 m long and 1 m wide, was identified on images obtained in September 2014 at the edge of a cliff named Aswan9. On 10 July 2015, the Rosetta Navigation Camera captured a large plume of dust that could be traced back to an area encompassing the Aswan escarpment7. Five days later, the OSIRIS camera observed a fresh, sharp and bright edge on the Aswan cliff. Here we report the first unambiguous link between an outburst and a cliff collapse on a comet. We establish a new dust-plume formation mechanism that does not necessarily require the breakup of pressurized crust or the presence of supervolatile material, as suggested by previous studies7. Moreover, the collapse revealed the fresh icy interior of the comet, which is characterized by an albedo >0.4, and provided the opportunity to study how the crumbling wall settled down to form a new talus. The evolution of the collapse of the Aswan cliff9, observed by the OSIRIS Narrow Angle Camera (NAC)10 and the Rosetta Navigation camera (NavCam), is shown in Fig. 1. We estimated a total outburst ejected mass of cometary material between 0.5 × 106 and 1.0 × 106 kg for the 10 July event. By applying stereo-photogrammetric methods11 using multiple OSIRIS images (Supplementary Table 1), we determined the total volume of material that collapsed from the Aswan cliff. In Fig. 2, the dataset that depicts the aspect of the cliff before and after the collapse is presented. By using pre- and post-collapse three-dimensional (3D) models (see Methods), we have been able to measure the dimensions of the collapsed overhang (Supplementary Figs 1–2), deriving a total volume of 2.20 × 104 m3, with a 1σ uncertainty of 0.34 × 104 m3.

Dates and versions

insu-01515572 , version 1 (27-04-2017)

Identifiers

Cite

Maurizio Pajola, S. Höfner, Jean-Baptiste Vincent, Nilda Oklay, Frank Scholten, et al.. The pristine interior of comet 67P revealed by the combined Aswan outburst and cliff collapse. Nature Astronomy, 2017, 1, pp.0092. ⟨10.1038/s41550-017-0092⟩. ⟨insu-01515572⟩
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