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Retrieving the distribution of comet 67P/Churyumov-Gerasimenko surface temperatures for individual Rosetta/VIRTIS-M spectra (pixel) by linear spectral unmixing - Method and first results -

Combe, J.-P. and McCord, Thomas B. and Capaccioni, F. and Filacchione, G. and Tosi, F. and Ciarniello, M. and Raponi, A. and Kappel, David and Rousseau, Batiste (2018) Retrieving the distribution of comet 67P/Churyumov-Gerasimenko surface temperatures for individual Rosetta/VIRTIS-M spectra (pixel) by linear spectral unmixing - Method and first results -. In: European Planetary Science Congress (EPSC) 2018, 12, p. 866. European Planetary Science Congress 2018, 16 - 21 Sep 2018, Berlin, Germany.

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Official URL: https://www.epsc2018.eu/

Abstract

Knowledge of surface temperature and its variations as function of illumination conditions is key for understanding the thermodynamical properties, the chemical properties and the physical structure of the regolith (porosity, roughness) of planets and small bodies in the solar system. The surface temperature can be retrieved from near-infrared spectra at wavelengths where thermal emission becomes non-negligible with respect to the reflected components. At 5 micron, the longest wavelength measured by VIRTIS-M on the Rosetta mission which observed comet 67P/Churyumov-Gerasimenko (67P/C-G), the minimum brightness temperature that can be measured is ~150K (instrumental noise equivalent temperature). The usual technique is to fit a Planck function to each spectrum, providing one temperature per pixel. However, the calculation of a distribution of temperatures per pixel is justified by the fact that the local topography changes at all scales resulting in variable illumination conditions (variable incidence angle and shadow casting) within the area covered by each pixel. This causes a distribution of temperatures which turns out in a distribution of thermal emission contributions. Furthermore, the combination of different thermal emission contributions (the linear combination of several Planck curves) is not a Planck function. Consequently, fitting one Planck function to a spectrum results in retrieving a value for the brightness temperature that is not representative of thermophysical properties of the regolith, because it is not the average of all temperatures in the area covered by that pixel.

Item URL in elib:https://elib.dlr.de/124810/
Document Type:Conference or Workshop Item (Poster)
Title:Retrieving the distribution of comet 67P/Churyumov-Gerasimenko surface temperatures for individual Rosetta/VIRTIS-M spectra (pixel) by linear spectral unmixing - Method and first results -
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Combe, J.-P.Bear Fight Center, A Columbus Technologies and Services Inc. Affiliate, P.O. Box 667, 22 Fiddler's Road, Winthrop, WA 98862, USAUNSPECIFIED
McCord, Thomas B.Bear Fight Institute, Winthrop, WA, United States.UNSPECIFIED
Capaccioni, F.INAF-IASF, italyUNSPECIFIED
Filacchione, G.INAF-IASF, Rome, ItalyUNSPECIFIED
Tosi, F.INAF-IASF Istituto di Astrofisica Spaziale e Fisica Cosmica, Roma ItalyUNSPECIFIED
Ciarniello, M.INAF-IASF, ItalyUNSPECIFIED
Raponi, A.INAF-IASF, ItalyUNSPECIFIED
Kappel, DavidDavid.Kappel (at) dlr.dehttps://orcid.org/0000-0002-0518-5548
Rousseau, BatisteLESIAUNSPECIFIED
Date:19 September 2018
Journal or Publication Title:European Planetary Science Congress (EPSC) 2018
Refereed publication:No
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Volume:12
Page Range:p. 866
Series Name:EPSC Abstracts
Status:Published
Keywords:Comet 67P, VIRTIS, Rosetta, Surface temperatures
Event Title:European Planetary Science Congress 2018
Event Location:Berlin, Germany
Event Type:international Conference
Event Dates:16 - 21 Sep 2018
Organizer:Europlanet
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 > Asteroids and Comets
Deposited By: Kappel, David
Deposited On:12 Dec 2018 10:27
Last Modified:31 Jul 2019 20:22

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