1. Seasonal erosion and restoration of the dust cover on comet 67P/Churyumov‐Gerasimenko as observed by OSIRIS onboard Rosetta
- Author
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Cesare Barbieri, Maria Antonieta Barucci, Jakob Deller, Gabriele Cremonese, Marco Fulle, Olivier Groussin, Jean-Loup Bertaux, J. Knollenberg, M. Küppers, Stefano Debei, Monica Lazzarin, L. M. Lara, Pedro J. Gutiérrez, Jean-Baptiste Vincent, C. Güttler, H. U. Keller, Maurizio Pajola, Géza Kovács, Ivano Bertini, Mohamed Ramy El-Maarry, Detlef Koschny, Hans Rickman, Nicolas Thomas, Holger Sierks, Sonia Fornasier, E. Kührt, A. Gicquel, J.-R. Kramm, Xian Shi, Dennis Bodewits, Nilda Oklay, X. Hu, V. Da Deppo, Björn Davidsson, Stefano Mottola, Cecilia Tubiana, Giampiero Naletto, P. Gutierrez-Marques, Rafael Rodrigo, Matteo Massironi, Stubbe F. Hviid, Jürgen Blum, Philippe Lamy, Wing-Huen Ip, Jessica Agarwal, Laurent Jorda, M. Hofmann, M. De Cecco, Bastian Gundlach, Steve Boudreault, J. J. López-Moreno, S. Höfner, Michael F. A'Hearn, Francesco Marzari, Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Max-Planck-Gesellschaft, Institut für Geophysik und Extraterrestrische Physik [Braunschweig] (IGEP), Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig], INAF - Osservatorio Astronomico di Trieste (OAT), Istituto Nazionale di Astrofisica (INAF), DLR Institut für Planetenforschung, Deutsches Zentrum für Luft- und Raumfahrt [Berlin] (DLR), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), NASA Ames Research Center (ARC), Department of Astronomy [College Park], University of Maryland [College Park], University of Maryland System-University of Maryland System, INAF - Osservatorio Astronomico di Padova (OAPD), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Dipartimento di Fisica e Astronomia 'Galileo Galilei', Università degli Studi di Padova = University of Padua (Unipd), Centro de Astrobiologia [Madrid] (CAB), Instituto Nacional de Técnica Aeroespacial (INTA)-Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), International Space Science Institute [Bern] (ISSI), Research and Scientific Support Department, ESTEC (RSSD), European Space Research and Technology Centre (ESTEC), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA), Department of Physics and Astronomy [Uppsala], Uppsala University, Space Research Centre of Polish Academy of Sciences (CBK), Polska Akademia Nauk = Polish Academy of Sciences (PAN), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centro di Ateneo di Studi e Attività Spaziali 'Giuseppe Colombo' (CISAS), CNR Istituto di Fotonica e Nanotecnologie [Padova] (IFN), National Research Council of Italy | Consiglio Nazionale delle Ricerche (CNR), Department of Industrial Engineering [Padova], Università degli Studi di Trento (UNITN), Physikalisches Institut [Bern], Universität Bern [Bern] (UNIBE), Laboratory for Atmospheric and Space Physics [Boulder] (LASP), University of Colorado [Boulder], Instituto de Astrofísica de Andalucía (IAA), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Institute of Astronomy [Taiwan] (IANCU), National Central University [Taiwan] (NCU), Operations Department (ESAC), European Space Astronomy Centre (ESAC), Department of Information Engineering [Padova] (DEI), Center for Space and Habitability (CSH), University of Bern, Max-Planck-Institut für Sonnensystemforschung (MPS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Universita degli Studi di Padova, Consejo Superior de Investigaciones Científicas [Madrid] (CSIC)-Instituto Nacional de Técnica Aeroespacial (INTA), European Space Agency (ESA)-European Space Agency (ESA), Consiglio Nazionale delle Ricerche [Roma] (CNR), Universität Bern [Bern], European Space Agency, Centre National de la Recherche Scientifique (France), Agenzia Spaziale Italiana, Swedish National Space Board, Ministerio de Economía y Competitividad (España), International Max Planck Research Schools, German Centre for Air and Space Travel, and California Institute of Technology (CALTECH)-NASA
- Subjects
Comets: general ,Comets: individual: 67P/Churyumov-Gerasimenko ,Astronomy and Astrophysics ,Space and Planetary Science ,67P/Churyumov-Gerasimenko ,010504 meteorology & atmospheric sciences ,Comet dust ,Comet ,Context (language use) ,Atmospheric sciences ,01 natural sciences ,Latitude ,Astrobiology ,thermal modeling ,individual: 67P/Churyumov [Comets] ,Rosetta ,0103 physical sciences ,medicine ,comets ,Ejecta ,010303 astronomy & astrophysics ,Comets: individual: 67P/Churyumov ,Gerasimenko ,0105 earth and related environmental sciences ,Physics ,Polar night ,[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph] ,general [Comets] ,Seasonality ,erosion ,medicine.disease ,13. Climate action ,[SDU]Sciences of the Universe [physics] ,Erosion ,sense organs - Abstract
Context. Dust deposits or dust cover are a prevalent morphology in the northern hemi-nucleus of comet 67P/Churyumov-Gerasimenko (67P). The evolution of the dust deposits was captured by the OSIRIS camera system onboard the Rosetta spacecraft having escorted the comet for over two years. The observations shed light on the fundamental role of cometary activity in shaping and transforming the surface morphology. Aims. We aim to present OSIRIS observations of surface changes over the dust deposits before and after perihelion. The distribution of changes and a timeline of their occurrence are provided. We perform a data analysis to quantify the surface changes and investigate their correlation to water activity from the dust deposits. We further discuss how the results of our investigation are related to other findings from the Rosetta mission. Methods. Surface changes were detected via systematic comparison of images, and quantified using shape-from-shading technique. Thermal models were applied to estimate the erosion of water ice in response to the increasing insolation over the areas where surface changes occurred. Modeling results were used for the interpretation of the observed surface changes. Results. Surface changes discussed here were concentrated at mid-latitudes, between about 20â-N and 40â-N, marking a global transition from the dust-covered to rugged terrains. The changes were distributed in open areas exposed to ample solar illumination and likely subject to enhanced surface erosion before perihelion. The occurrence of changes followed the southward migration of the sub-solar point across the latitudes of their distribution. The erosion at locations of most changes was at least about 0.5 m, but most likely did not exceed several meters. The erosive features before perihelion had given way to a fresh, smooth cover of dust deposits after perihelion, suggesting that the dust deposits had been globally restored by at least about 1 m with ejecta from the intensely illuminated southern hemi-nucleus around perihelion, when the north was inactive during polar night. Conclusions. The erosion and restoration of the northern dust deposits are morphological expressions of seasonality on 67P. Based on observations and thermal modeling results, it is inferred that the dust deposits contained a few percent of water ice in mass on average. Local inhomogeneity in water abundance at spatial scales below tens of meters is likely. We suspect that dust ejected from the deposits may not have escaped the comet in bulk. That is, at least half of the ejected mass was afloat in the inner-coma or/and redeposited over other areas of the nucleus.© 2017 ESO., X. Hu acknowledges the financial support from the International Max Planck Research School for Solar System Science in Gottingen.The support of the national funding agencies of Germany (DLR), France (CNES), Italy (ASI), Spain (MEC), Sweden (SNSB), and the ESA Technical Directorate is gratefully acknowledged.
- Published
- 2017