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Spectrophotometry, colors, and photometric properties of the 67P/Churyumov-Gerasimenko nucleus from the OSIRIS instrument onboard the ROSETTA mission

Fornasier, Sonia and Hasselmann, Pedro and Feller, Clement and Barucci, Maria Antonetta and Lara, Luisa and Oklay, Nilda and Tubiana, Cecilia and Besse, Sebastien and Scholten, Frank and Sierks, Holger and Leyrat, Cedric and La Forgia, Fiorangela and Lazzarin, Monica and Pajola, Maurizio and Thomas, Nicholas and OSIRIS, Team (2015) Spectrophotometry, colors, and photometric properties of the 67P/Churyumov-Gerasimenko nucleus from the OSIRIS instrument onboard the ROSETTA mission. EGU General Assembly, 12-17 Apr 2015, Vienna, Austria.

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Official URL: http://meetingorganizer.copernicus.org/EGU2015/EGU2015-9241-1.pdf

Abstract

Rosetta is the cornerstone mission of the European Space Agency devoted to the study of Solar System minor bodies. Launched on 2 March 2004, Rosetta arrived on August 6, 2014, at the comet 67P/Churyumov-Gerasimenko after 10 years of interplanetary journey. Rosetta is now in the main science escort phase of the comet after the successful delivery of the lander Philae on its surface on November 12, 2014. In this work we present the results on the 67P nucleus physical properties derived from the OSIRIS imaging system observations obtained in July- mid August 2014, during the comet approach phase and the first bound orbits. In this timeframe, OSIRIS has mapped the comet surface with a resolution up to 2 m/px with several filters covering the 250-1000 nm range, and at different phase angles (1.3-54 degrees). The images have been reduced using the OSIRIS standard pipeline, and then transformed into I/F reflectance. A 3D shape model of the nucleus, determined from the images obtained during the mapping phase, has been used to retrieve the illumination and geometric conditions of each image. Color cubes of the surface have been hence produced by stacking registered and photometrically corrected images. Globally, the nucleus has spectrophotometric properties in the NUV-VIS-NIR range similar to those of bare cometary nuclei, of primitive D-type asteroids such us Jupiter Trojans, and of the moderately red Transneptunians and Centaurs. No clear absorption bands have been detected so far at the resolution of the used filters. The global spectral slope, evaluated in the 535-880 nm range, varies between 11 %/(100 nm) at a phase angle of 1.3 degrees and 16 %/(100 nm) at a phase angle of 52 degrees, implying a significant phase reddening. Despite the different types of terrains and morphological features seen on the comet (Thomas et al. 2015), the nucleus shows small color variations, with the notable exception of the Hapi region (Sierks et al., 2015). This region is located between the two lobes of the comet, and is both the most active and brightest surface on the comet. This region has a bluer spectral slope than the darker regions that we interpret being caused by a higher abundance of water ice in the surface composition, although we note that no water ice absorption bands have been detected with the VIRTIS infrared imaging spectrometer during the August-September observations at resolutions of 15-25 m/px (Capaccioni et al. 2015). The absence of large areas of water ice rich mixtures in VIRTIS data may be attributed to their lower spatial resolution than the OSIRIS images, together with the presence of non-volatile materials that may mask the water ice spectral absorptions. We will present the results of the global photometric properties in several filters, derived using the Hapke model, together with the analysis of the local colors spectrophotometry, and albedo variations of the 67P nucleus. This unique data set places further constraints on the origin and distribution of cometary activity on the surface.

Item URL in elib:https://elib.dlr.de/101349/
Document Type:Conference or Workshop Item (Poster)
Title:Spectrophotometry, colors, and photometric properties of the 67P/Churyumov-Gerasimenko nucleus from the OSIRIS instrument onboard the ROSETTA mission
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Fornasier, SoniaObservatoire de Paris-Meudon, FranceUNSPECIFIED
Hasselmann, PedroLESIA, Observatoire de Paris, CNRS, UPMC Univ Paris 06, Univ. Paris-Diderot, 5 Place J. Janssen, 92195 Meudon Pricipal Cedex, FranceUNSPECIFIED
Feller, ClementLESIA, Observatoire de Paris, CNRS, UPMC Univ Paris 06, Univ. Paris-Diderot, 5 Place J. Janssen, 92195 Meudon Pricipal Cedex, FranceUNSPECIFIED
Barucci, Maria AntonettaObservatoire de Paris, Meudon, FranceUNSPECIFIED
Lara, LuisaInstituto de Astrofisica de AndaluciaUNSPECIFIED
Oklay, NildaMax-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg, 3, 37077, Göttingen, GermanyUNSPECIFIED
Tubiana, CeciliaMPI für Sonnensystemforschung, Katlenburg-Lindau, GermanyUNSPECIFIED
Besse, SebastienScientific Support Office, European Space Agency, 2201, Noordwijk, Netherlands.UNSPECIFIED
Scholten, Frankfrank.scholten (at) dlr.deUNSPECIFIED
Sierks, HolgerMax-Planck-Institut für SonnensystemforschungUNSPECIFIED
Leyrat, CedricLESIA, Observatoire de Paris, CNRS, UPMC Univ Paris 06, Univ. Paris-Diderot, 5 Place J. Janssen, 92195 Meudon Pricipal Cedex, FranceUNSPECIFIED
La Forgia, FiorangelaUniversity of Padova, Department of Physics and Astronomy, Vicolo dell'Osservatorio 3, 35122 Padova, ItalyUNSPECIFIED
Lazzarin, MonicaUniversity of Padova, Department of Physics and Astronomy, Vicolo dell'Osservatorio 3, 35122 Padova, ItalyUNSPECIFIED
Pajola, MaurizioCentro di Ateneo di Studi ed Attivitá Spaziali, “Giuseppe Colombo” (CISAS), University of Padova, Via Venezia 15, 35131 Padova, ItalyUNSPECIFIED
Thomas, NicholasUniv. Bern, CHUNSPECIFIED
OSIRIS, TeamUNSPECIFIEDUNSPECIFIED
Date:2015
Refereed publication:No
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:Rosetta, 67P, OSIRIS, spectophotometry, color, photometry
Event Title:EGU General Assembly
Event Location:Vienna, Austria
Event Type:international Conference
Event Dates:12-17 Apr 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 > Planetary Geodesy
Deposited By: Scholten, Dipl.-Ing. Frank
Deposited On:05 Jan 2016 12:57
Last Modified:31 Jul 2019 19:58

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