English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT

Released

Journal Article

Global-scale brittle plastic rheology at the cometesimals merging of comet 67P/Churyumov–Gerasimenko

MPS-Authors
/persons/resource/persons160269

Güttler,  Carsten
Department Planets and Comets, Max Planck Institute for Solar System Research, Max Planck Society;

/persons/resource/persons140545

Deller,  Jakob
Department Planets and Comets, Max Planck Institute for Solar System Research, Max Planck Society;

/persons/resource/persons104212

Sierks,  Holger
Department Planets and Comets, Max Planck Institute for Solar System Research, Max Planck Society;

/persons/resource/persons104259

Tubiana,  Cecilia
Department Planets and Comets, Max Planck Institute for Solar System Research, Max Planck Society;

External Resource
No external resources are shared
Fulltext (public)
There are no public fulltexts stored in PuRe
Supplementary Material (public)
There is no public supplementary material available
Citation

Franceschi, M., Penasa, L., Massironi, M., Naletto, G., Ferrari, S., Fondriest, M., et al. (2020). Global-scale brittle plastic rheology at the cometesimals merging of comet 67P/Churyumov–Gerasimenko. Proceedings of the National Academy of Sciences of the United States of America, 117(19), 10181-10187. doi:10.1073/pnas.1914552117.


Cite as: http://hdl.handle.net/21.11116/0000-0006-9F3F-2
Abstract
Observations of comet nuclei indicate that the main constituent is a mix of ice and refractory materials characterized by high porosity (70–75%) and low bulk strength (10−4–10−6 MPa); however, the nature and physical properties of these materials remain largely unknown. By combining surface inspection of comet 67P/Churyumov–Gerasimenko and three-dimensional (3D) modeling of the independent concentric sets of layers that make up the structure of its two lobes, we provide clues about the large-scale rheological behavior of the nucleus and the kinematics of the impact that originated it. Large folds in the layered structure indicate that the merging of the two cometesimals involved reciprocal motion with dextral strike–slip kinematics that bent the layers in the contact area without obliterating them. Widespread long cracks and the evidence of relevant mass loss in absence of large density variations within the comet’s body testify that large-scale deformation occurred in a brittle-plastic regime and was accommodated through folding and fracturing. Comparison of refined 3D geologic models of the lobes with triaxial ellipsoids that suitably represent the overall layers arrangement reveals characteristics that are consistent with an impact between two roughly ellipsoidal cometesimals that produced large-scale axial compression and transversal elongation. The observed features imply global transfer of impact-related shortening into transversal strain. These elements delineate a model for the global rheology of cometesimals that could be possible evoking a prominent bonding action of ice and, to a minor extent, organics.