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The global surface composition of 67P/CG nucleus by Rosetta/VIRTIS. (I) Prelanding mission phase

Filacchione, G. and Capaccioni, F. and Ciarniello, M. and Raponi, A. and Tosi, F. and De Sanctis, M.C. and Erard, S. and Bockelee-Morvan, D. and Leyrat, C. and Arnold, Gabriele and Schmitt, B. and Quirico, E. and Piccioni, G. and Migliorini, A. and Capria, M. T. and Palomba, E. and Cerroni, P. and Longobardo, A and Barucci, M. A. and Fornasier, S. and Carlson, R. W. and Jaumann, R. and Stephan, Katrin and Moroz, Liubov and Kappel, David and Rousseau, Batiste and Fonti, S. and Mancarella, F. and Despan, D. and Faure, M. (2016) The global surface composition of 67P/CG nucleus by Rosetta/VIRTIS. (I) Prelanding mission phase. Icarus, 274, pp. 334-349. Elsevier. DOI: 10.1016/j.icarus.2016.02.055 ISSN 0019-1035

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Official URL: http://dx.doi.org/10.1016/j.icarus.2016.02.055

Abstract

From August to November 2014 the Rosetta orbiter has performed an extensive observation campaign aimed at the characterization of 67P/CG nucleus properties and to the selection of the Philae landing site. The campaign led to the production of a global map of the illuminated portion of 67P/CG nucleus. During this prelanding phase the comet's heliocentric distance decreased from 3.62 to 2.93 AU while Rosetta was orbiting around the nucleus at distances between 100 to 10 km. VIRTIS-M, the Visible and InfraRed Thermal Imaging Spectrometer - Mapping channel (Coradini et al., [2007] Space Sci. Rev., 128, 529-559) onboard the orbiter, has acquired 0.25-5.1 μm hyperspectral data of the entire illuminated surface, e.g. the north hemisphere and the equatorial regions, with spatial resolution between 2.5 and 25 m/pixel. I/F spectra have been corrected for thermal emission removal in the 3.5-5.1 μm range and for surface's photometric response. The resulting reflectance spectra have been used to compute several Cometary Spectral Indicators (CSI): single scattering albedo at 0.55 μm, 0.5-0.8 μm and 1.0-2.5 μm spectral slopes, 3.2 μm organic material and 2.0 μm water ice band parameters (center, depth) with the aim to map their spatial distribution on the surface and to study their temporal variability as the nucleus moved towards the Sun. Indeed, throughout the investigated period, the nucleus surface shows a significant increase of the single scattering albedo along with a decrease of the 0.5-0.8 and 1.0-2.5 μm spectral slopes, indicating a flattening of the reflectance. We attribute the origin of this effect to the partial removal of the dust layer caused by the increased contribution of water sublimation to the gaseous activity as comet crossed the frost-line. The regions more active at the time of these observations, like Hapi in the neck/north pole area, appear brighter, bluer and richer in organic material than the rest of the large and small lobe of the nucleus. The parallel coordinates method (Inselberg [1985] Vis. Comput., 1, 69-91) has been used to identify associations between average values of the spectral indicators and the properties of the geomorphological units as defined by (Thomas et al., [2015] Science, 347, 6220) and (El-Maarry et al., [2015] Astron. Astrophys., 583, A26). Three classes have been identified (smooth/active areas, dust covered areas and depressions), which can be clustered on the basis of the 3.2 μm organic material's band depth, while consolidated terrains show a high variability of the spectral properties resulting being distributed across all three classes. These results show how the spectral variability of the nucleus surface is more variegated than the morphological classes and that 67P/CG surface properties are dynamical, changing with the heliocentric distance and with activity processes.

Item URL in elib:https://elib.dlr.de/107055/
Document Type:Article
Title:The global surface composition of 67P/CG nucleus by Rosetta/VIRTIS. (I) Prelanding mission phase
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Filacchione, G.INAF-IASF, Rome, ItalyUNSPECIFIED
Capaccioni, F.INAF-IASF, italyUNSPECIFIED
Ciarniello, M.INAF-IASF, ItalyUNSPECIFIED
Raponi, A.INAF-IASF, ItalyUNSPECIFIED
Tosi, F.INAF-IASF Istituto di Astrofisica Spaziale e Fisica Cosmica, Roma ItalyUNSPECIFIED
De Sanctis, M.C.Istituto Nazionale di Astrofisica, Rome, Italy.UNSPECIFIED
Erard, S.LESIAUNSPECIFIED
Bockelee-Morvan, D.Observatoire de Paris, MeudonUNSPECIFIED
Leyrat, C.LESIAUNSPECIFIED
Arnold, GabrieleGabriele.Arnold (at) dlr.deUNSPECIFIED
Schmitt, B.Grenoble Planetology LaboratoryUNSPECIFIED
Quirico, E.Laboratory of Planetology, CNRS Joseph Fourier UniversityUNSPECIFIED
Piccioni, G.INAF-IASFUNSPECIFIED
Migliorini, A.INAF-IASFUNSPECIFIED
Capria, M. T.Instituto di Astrofisica Spaziale e Fisica Cosmica, Roma, ItalyUNSPECIFIED
Palomba, E.Institute for Interplanetary Space Physics - INAF, Rome, ItalyUNSPECIFIED
Cerroni, P.INAF-IASF, Rome, ItalyUNSPECIFIED
Longobardo, AINAF-LAPS, Via del Fosso del Cavaliere 100, I-00133 Rome, ItalyUNSPECIFIED
Barucci, M. A.Observatoire de Paris, Meudon, FranceUNSPECIFIED
Fornasier, S.Observatoire de Paris-Meudon, FranceUNSPECIFIED
Carlson, R. W.Jet Propulsion LaboratoryUNSPECIFIED
Jaumann, R.ralf.jaumann (at) dlr.deUNSPECIFIED
Stephan, KatrinKatrin.Stephan (at) dlr.deUNSPECIFIED
Moroz, LiubovLjuba.Moroz (at) dlr.deUNSPECIFIED
Kappel, DavidDavid.Kappel (at) dlr.deUNSPECIFIED
Rousseau, BatisteLESIAUNSPECIFIED
Fonti, S.Dipartimento di Fisica, Università di Lecce, ItalyUNSPECIFIED
Mancarella, F.Dipartimento di Matematica e Fisica "E. De Giorgi", Università del Salento, Lecce, ItalyUNSPECIFIED
Despan, D.Laboratoire d’Etudes Spatiales et d’Instrumentation en Astrophysique, Observatoire de Paris/CNRS/Université Pierre et Marie Curie/Université Paris-Diderot, Meudon, FranceUNSPECIFIED
Faure, M.Universite Grenoble Alpes, CNRS, IPAG, Grenoble, FranceUNSPECIFIED
Date:16 March 2016
Journal or Publication Title:Icarus
Refereed publication:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:274
DOI :10.1016/j.icarus.2016.02.055
Page Range:pp. 334-349
Publisher:Elsevier
ISSN:0019-1035
Status:Published
Keywords:Comet, Nucleus, Composition, Spectroscopy, Rosetta
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Science and Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Erforschung des Weltraums
DLR - Research theme (Project):R - Projekt ROSETTA Instrumente
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research
Institute of Planetary Research > Asteroids and Comets
Institute of Planetary Research > Planetary Geology
Deposited By: Kappel, David
Deposited On:25 Oct 2016 15:58
Last Modified:10 Jan 2019 15:54

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