Fractures on comet 67P/Churyumov-Gerasimenko observed by Rosetta/OSIRIS

• Published in: Geophysical research letters 2015-07, Vol.42 (13), p.5170-5178
• Main Authors: El-Maarry, M. R., Thomas, N., Gracia-Berná, A., Marschall, R., Auger, A.-T., Groussin, O., Mottola, S., Pajola, M., Massironi, M., Marchi, S., Höfner, S., Preusker, F., Scholten, F., Jorda, L., Kührt, E., Keller, H. U., Sierks, H., A'Hearn, M. F., Barbieri, C., Barucci, M. A., Bertaux, J.-L., Bertini, I., Cremonese, G., Da Deppo, V., Davidsson, B., Debei, S., De Cecco, M., Deller, J., Güttler, C., Fornasier, S., Fulle, M., Gutierrez, P. J., Hofmann, M., Hviid, S. F., Ip, W.-H., Knollenberg, J., Koschny, D., Kovacs, G., Kramm, J.-R., Küppers, M., Lamy, P. L., Lara, L. M., Lazzarin, M., Lopez Moreno, J. J., Marzari, F., Michalik, H., Naletto, G., Oklay, N., Pommerol, A., Rickman, H., Rodrigo, R., Tubiana, C., Vincent, J.-B.
• Format: Article
• Language: English
• Subjects: Astrophysics; Comet 67P; Comet nuclei; Comets; Contraction; Daily temperatures; Earth and Planetary Astrophysics; Erosion; Evolution; Formations; Fracture mechanics; Fractures; Gradients; Imaging techniques; Infrared imaging; Infrared spectroscopy; Insolation; Insulating materials; Mathematical models; Mathematical morphology; Morphology; Networks; Nuclei; Nucleus; Onboard; OSIRIS; Regional analysis; Rosetta; Rosetta mission; Sciences of the Universe; Spacecraft; Stresses; Temperature; Temperature effects; Temperature range; Thermal analysis; Thermal contraction; Thermal insulation; Thermal models; Topology; Weathering
• ISSN: 0094-8276; 1944-8007; 1944-8007
• DOI: 10.1002/2015GL064500

The Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) experiment onboard the Rosetta spacecraft currently orbiting comet 67P/Churyumov‐Gerasimenko has yielded unprecedented views of a comet's nucleus. We present here the first ever observations of meter‐scale fractures on the surface of a comet. Some of these fractures form polygonal networks. We present an initial assessment of their morphology, topology, and regional distribution. Fractures are ubiquitous on the surface of the comet's nucleus. Furthermore, they occur in various settings and show different topologies suggesting numerous formation mechanisms, which include thermal insulation weathering, orbital‐induced stresses, and possibly seasonal thermal contraction. However, we conclude that thermal insolation weathering is responsible for creating most of the observed fractures based on their morphology and setting in addition to thermal models that indicate diurnal temperature ranges exceeding 200 K and thermal gradients of ~15 K/min at perihelion are possible. Finally, we suggest that fractures could be a facilitator in surface evolution and long‐term erosion. Key Points Fractures are observed on the surface of a comet for the first time Different fracture settings and topologies suggest various formation mechanisms Fractures may be a key driver in the evolution of the surface