More than two years has gone from the descent of the Rosetta spacecraft on the 67P/Churyumov Gerasimenko comet. Thanks to data analysis, scientists are still discovering new information on the geology and evolution of the comet.
“The cover of the March issue of the Nature Geoscience journal highlights the results of the research conducted using the high resolution images taken by Osiris” says Vania Da Deppo researcher at the Cnr-Ifn Padova. ”In the paper the geologist Christophe Matonti working at the Aix-Marseille University (France), and leading an international team of scientists, shows a geological and morphological analysis of the shear-fractures present on the comet surface and in particular on the neck.”
Osiris is a sophisticated instrument conceived to obtain wide angle and high resolution images, and it has monitored continuously, during the entire mission, the evolution of the comet surface.
Osiris is the result of a joint effort of many European institutions; as for the Italian contribution, the Institute for Photonics and Nanotechnologies of the National Research Council in Padova (Cnr-Ifn) has been involved together with the University of Padova, the National Institute for Astrophysics and the 'Centro interdipartimentale di studi e attività spaziali (Cisas)'.
Bilobate comets are a common configuration among comets, but the factors shaping these bodies are largely unknown. The 67P/Churyumov Gerasimenko comet surface and interior exhibit shear-fracture and fault networks, on spatial scales of tens to hundreds of metres. Fractures propagate up to 500 meters below the surface through a mechanically homogeneous material.
Fracture network analysis and stress modelling show that shear deformation generates fracture networks that control mechanical surface erosion, particularly in the strongly marked neck trough of the comet, exposing its interior. Thus shear deformation shapes and structures the surface and interior of bilobate comets, particularly in the outer Solar System where water ice sublimation is negligible.
Vania Da Deppo
Cnr - Istituto di fotonica e nanotecnologie
Via Trasea 7
35131 Padova - Italy