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Comet 67P: Thermal Maps and Local Properties as Derived from Rosetta/VIRTIS data

Tosi, F. and Capria, M. T. and Capaccioni, F. and Filacchione, G. and Erard, S. and Leyrat, C. and Bockelee-Morvan, D. and De Sanctis, M.C. and Raponi, A. and Ciarnello, M. and Schmitt, B. and Arnold, Gabriele and Mottola, S. and Fonti, S. and Palomba, E. and Longobardo, A and Cerroni, P. and Piccioni, G. and Drossart, P. and Kührt, E. (2015) Comet 67P: Thermal Maps and Local Properties as Derived from Rosetta/VIRTIS data. In: Geophysical Research Abstracts, 17, p. 11625. EGU General Assembly 2015, 12. April - 17. April 2015, Vienna, Austria.

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Official URL: http://meetingorganizer.copernicus.org/EGU2015/EGU2015-11625.pdf

Abstract

Comet 67P is shown to be everywhere rich in organic materials with little to no water ice visible on the surface. In the range of heliocentric distances from 3.59 to 2.74 AU, daytime observed surface temperatures retrieved from VIRTIS data are overall comprised in the range between 180 and 220 K, which is incompatible with large exposures of water ice and is consistent with a low-albedo, organics-rich surface. The accuracy of temperature retrieval is as good as a few K in regions of the comet unaffected by shadowing or limb proximity. Maximum temperature values as high as 230 K have been recorded in very few places. The highest values of surface temperature in the early Mapping phase were obtained in August 2014, during observations at small phase angles implying that the observed surface has a large predominance of small incidence angles, and local solar times (LST) centered around the maximum daily insolation. In all cases, direct correlation with topographic features is observed, i.e. largest temperature values are generally associated with the smallest values of illumination angles. So far, there is no evidence of thermal anomalies, i.e. places of the surface that are intrinsically warmer or cooler than surrounding terrains observed at the same local solar time and under similar solar illumination. For a given LST, the maximum temperature mainly depends on the solar incidence angle and on surface properties such as thermal inertia and albedo. Since VIRTIS is able to observe the same point of the surface on various occasions under different conditions of solar illumination and LST, it is possible to reconstruct the temperature of that point at different times of the comet’s day, thus building diurnal profiles of temperature that are useful to constrain thermal inertia. The availability of spatially-resolved, accurate temperature observations, significantly spaced out in local solar time, provides clues to the physical structure local features, which complements the compositional investigation based on imaging spectroscopy data collected at shorter wavelengths. In the VIRTIS thermal images, a note of great interest is provided by the ‘neck’ of the comet close to the ‘body’, where, because of the concave shape, the ‘head’ casts prominent shadows on some areas when they experience maximum daily insolation. This is a place potentially subjected to considerable thermal stresses. We evaluate both the spatial thermal gradients and the temporal thermal gradients, providing implications for the surface structure.

Item URL in elib:https://elib.dlr.de/100900/
Document Type:Conference or Workshop Item (Speech)
Title:Comet 67P: Thermal Maps and Local Properties as Derived from Rosetta/VIRTIS data
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Tosi, F.INAF-IASF Istituto di Astrofisica Spaziale e Fisica Cosmica, Roma ItalyUNSPECIFIED
Capria, M. T.Instituto di Astrofisica Spaziale e Fisica Cosmica, Roma, ItalyUNSPECIFIED
Capaccioni, F.INAF-IASF, italyUNSPECIFIED
Filacchione, G.INAF-IASF, Rome, ItalyUNSPECIFIED
Erard, S.LESIAUNSPECIFIED
Leyrat, C.LESIAUNSPECIFIED
Bockelee-Morvan, D.Observatoire de Paris, MeudonUNSPECIFIED
De Sanctis, M.C.Istituto Nazionale di Astrofisica, Rome, Italy.UNSPECIFIED
Raponi, A.INAF-IASF, ItalyUNSPECIFIED
Ciarnello, M.INAF-IASF, ItalyUNSPECIFIED
Schmitt, B.Grenoble Planetology LaboratoryUNSPECIFIED
Arnold, GabrieleGabriele.Arnold (at) dlr.deUNSPECIFIED
Mottola, S.stefano.mottola (at) dlr.deUNSPECIFIED
Fonti, S.Dipartimento di Fisica, Università di Lecce, ItalyUNSPECIFIED
Palomba, E.Institute for Interplanetary Space Physics - INAF, Rome, ItalyUNSPECIFIED
Longobardo, AINAF-LAPS, Via del Fosso del Cavaliere 100, I-00133 Rome, ItalyUNSPECIFIED
Cerroni, P.INAF-IASF, Rome, ItalyUNSPECIFIED
Piccioni, G.INAF-IASFUNSPECIFIED
Drossart, P.Observatoire de Paris, Meudon, FranceUNSPECIFIED
Kührt, E.ekkehard.kuehrt (at) dlr.deUNSPECIFIED
Date:13 April 2015
Journal or Publication Title:Geophysical Research Abstracts
Refereed publication:No
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Volume:17
Page Range:p. 11625
Status:Published
Keywords:VIRTIS, Rosetta, 67P, temperature
Event Title:EGU General Assembly 2015
Event Location:Vienna, Austria
Event Type:international Conference
Event Dates:12. April - 17. April 2015
Organizer:European Geosciences Union
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 > Leitungsbereich PF
Institute of Planetary Research > Asteroids and Comets
Deposited By: Kappel, David
Deposited On:17 Dec 2015 08:51
Last Modified:31 Jul 2019 19:58

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