Properties of the 67P/Churyumov-Gerasimenko interior revealed by CONSERT radar

Creators: Kofman, Wlodek; Elachi, Charles; van Zyl, Jakob

Abstract

The Philae lander provides a unique opportunity to investigate the internal structure of a comet nucleus, providing information about its formation and evolution in the early solar system. We present Comet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT) measurements of the interior of Comet 67P/Churyumov-Gerasimenko. From the propagation time and form of the signals, the upper part of the "head" of 67P is fairly homogeneous on a spatial scale of tens of meters. CONSERT also reduced the size of the uncertainty of Philae's final landing site down to approximately 21 by 34 square meters. The average permittivity is about 1.27, suggesting that this region has a volumetric dust/ice ratio of 0.4 to 2.6 and a porosity of 75 to 85%. The dust component may be comparable to that of carbonaceous chondrites.

Additional Information

© 2015 American Association for the Advancement of Science. Received for publication 5 March 2015. Accepted for publication 30 June 2015. Rosetta is an European Space Agency (ESA) mission with contributions from its member states and National Aeronautics and Space Administration (NASA). Rosetta's Philae lander is provided by a consortium led by Deutsches Zentrum für Luft- und Raumfahrt (DLR), MPS, Centre National d'Etudes Spatiales (CNES), and Agenzia Spaziale Italiana (ASI). The CONSERT instrument was designed, built, and operated by IPAG, LATMOS, and MPS and was financially supported by CNES, CNRS, Université Joseph Fourier (UJF), DLR, and MPS. The authors thank the teams of Rosetta [Rosetta Mission Operation Center (RMOC) and Rosetta Science Ground Segment (RSGS)] and Philae (Rosetta Lander Control Center (LCC) and Rosetta Lander Science Operation & Navigation Center (SONC)) for making possible the CONSERT operations. Most of the computations presented in this paper were performed using the Calcul Intensif, Modélisation, Expérimentation Numérique (CIMENT) infrastructure (https://ciment.ujf-grenoble.fr), including the Froggy platform, which is supported by the Rhône-Alpes region (GRANT CPER07_13 CIRA), the OSUG@2020 labex (reference ANR10 LABX56), the Equip@Meso project (reference ANR-10-EQPX-29-01) of the program Investissements d'Avenir supervised by the Agence Nationale pour la Recherche and France-Grille (www.france-grilles.fr). Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. All CONSERT data are released through the PSA archive of ESA (www.rssd.esa.int/index.php?project=PSA&page=rosetta).

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