Titan's surface and atmosphere from Cassini/VIMS data with updated methane opacity

International audience; We present an analysis of Titan data acquired by the Cassini Visual and Infrared Mapping Spectrometer (VIMS), making use of recent improvements in methane spectroscopic parameters in the region 1.3-5.2 μm. We first analyzed VIMS spectra covering a 8 × 10-km2 area near the Huygens landing site in order to constrain the single scattering albedo (ω0) of the aerosols over all of the VIMS spectral range. Our aerosol model agrees with that derived from Huygens Probe Descent Imager/Spectral Radiometer (DISR) in situ measurements below 1.6 μm. At longer wavelengths, ω0 steadily decreases from 0.92 at 1.6 μm to about 0.70 at 2.5 μm and abruptly drops to about 0.50 near 2.6 μm…

Simulations of Titan Observations in the 1.58 Micron Transparency Window with High-Resolution, Low Temperature CRDS Spectra

Le méthane dans l'atmosphère de Titan. De la spectroscopie fondamentale à la planétologie

Le méthane (CH4) joue sur Tian, le plus gros satellite de Saturne, un rôle similaire à celui de l'eau sur Terre. Il y est de plus à l'origine d'une chimie organique complexe. La spectroscopie étant la technique privilégiée pour mesurer le CH4 dans les atmosphères planétaires, des modèles précis de l'absorption de la lumière par cette molécule doivent être développés. Les résultats récents obtenus dans ce domaine à l'Institut Carnot de Bourgogne, en collaboration étroite avec des planétologues, permettent notamment de contribuer à l'interprétation des résultats de la mission Cassini-Huygens.

Le Cycle du Méthane sur Titan

Ariel: Enabling planetary science across light-years

Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey, was adopted as the fourth medium-class mission in ESA's Cosmic Vision programme to be launched in 2029. During its 4-year mission, Ariel will study what exoplanets are made of, how they formed and how they evolve, by surveying a diverse sample of about 1000 extrasolar planets, simultaneously in visible and infrared wavelengths. It is the first mission dedicated to measuring the chemical composition and thermal structures of hundreds of transiting exoplanets, enabling planetary science far beyond the boundaries of the Solar System. The payload consists of an off-axis Cassegrain telescope (primary mirror 1100 mm x 730 mm e…

The 2009 Edition of the GEISA Spectroscopic Database

The updated 2009 edition of the spectroscopic database GEISA (Gestion et Etude des Informations Spectroscopiques Atmosphériques; Management and Study of Atmospheric Spectroscopic Information) is described in this paper. GEISA is a computer-accessible system comprising three independent sub-databases devoted, respectively, to: line parameters, infrared and ultraviolet/visible absorption cross-sections, microphysical and optical properties of atmospheric aerosols. In this edition, 50 molecules are involved in the line parameters sub-database, including 111 isotopologues, for a total of 3,807,997 entries, in the spectral range from 10-6 to 35,877.031cm-1.The successful performances of the new …

Corrigendum to "Titan's surface and atmosphere from Cassini/VIMS data with updated methane opacity" [Icarus 226 (2013) 470-486]

0019-1035/$ see front matter 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.icarus.2013.07.015 DOI of original article: http://dx.doi.org/10.1016/j.icarus.2013.05.033 ⇑ Corresponding author. Address: LESIA, Observatoire de Paris, Section de Meudon, 92195 Meudon Cedex, France. Fax: +33 145072806. E-mail address: bruno.bezard@obspm.fr (B. Bezard). 1 Present address: Foundation ‘‘La main a la pâte’’, Montrouge, France. M. Hirtzig , B. Bezard a,⇑, E. Lellouch , A. Coustenis , C. de Bergh , P. Drossart , A. Campargue , V. Boudon , V. Tyuterev , P. Rannou , T. Cours , S. Kassi , A. Nikitin , D. Mondelain , S. Rodriguez , S. Le Mouelic g

Titan's surface albedo variations over a Titan season from near-infrared CFHT/FTS spectra

International audience; We have observed Titan in a series of campaigns from 1991 to 1996 with the Fourier Transform Spectrometer on the CFH telescope. The data acquired provide a lightcurve from the geometric albedos in the 0.9–View the MathML source spectral region. The 1991–1993 data were previously analyzed in Coustenis et al. [1995. Titan's surface: composition and variability from its near-infrared albedo. Icarus 118, 87–104] with a spherical particle code by McKay et al. [1989. The thermal structure of Titan's atmosphere. Icarus 80, 23–53]. We present here three new datasets from the 1994, 1995 and 1996 observations, with additional information from the 0.94-μm methane window on Tita…

Methane in Titan's atmosphere: from fundamental spectroscopy to planetology

The methane molecule (CH4) is relatively abundant in the Universe and in particular in our Solar System. On Earth, it is the main compound of natural gas and is also the second greenhouse gas of anthropic origin. On Saturn's satellite Titan it plays a role similar to water on Earth and leads to a complex chemistry.

Le méthane dans l’atmosphère de Titan - De la spectroscopie fondamentale à la planétologie

Le methane (CH4) joue sur Tian, le plus gros satellite de Saturne, un role similaire a celui de l'eau sur Terre. Il y est de plus a l'origine d'une chimie organique complexe. La spectroscopie etant la technique privilegiee pour mesurer le CH4 dans les atmospheres planetaires, des modeles precis de l'absorption de la lumiere par cette molecule doivent etre developpes. Les resultats recents obtenus dans ce domaine a l'Institut Carnot de Bourgogne, en collaboration etroite avec des planetologues, permettent notamment de contribuer a l'interpretation des resultats de la mission Cassini-Huygens.

Titan's 3-micron spectral region from ISO high-resolution spectroscopy

Abstract The near-infrared spectrum of Titan, Saturn's largest moon and one of the Cassini/Huygens' space mission primary targets, covers the 0.8 to 5 micron region in which it shows several weak CH 4 absorption regions, and in particular one centered near 2.75 micron. Due to the interference of telluric absorption, only part of this window region (2.9–3.1 μm) has previously been observed from the ground [Noll, K.S., Geballe, T.R., Knacke, R., Pendleton, F., Yvonne, J., 1996. Icarus 124, 625–631; Griffith, C.A., Owen, T., Miller, G.A., Geballe, T., 1998. Nature 395, 575–578; Griffith, C.A., Owen, T., Geballe, T.R., Rayner, J., Rannou, P., 2003. Science 300, 628–630; Geballe, T.R., Kim, S.J.…

Applications of a New Methane Linelist to the Modeling of Titan's Spectrum in the 1.58 Micron Window

International audience

Recent Applications and Future Prospects of Methane Spectroscopy to the Atmosphere of Titan

EXO-PLANETARY HIGH-TEMPERATURE HYDROCARBONS BY EMISSION AND ABSORPTION SPECTROSCOPY (e-PYTHEAS PROJECT)

International audience; e-PYTHEAS is a multidisciplinary project which combines theoretical and experimental work with exoplanet modelling applications. It sits on the frontier between molecular physics, theoretical chemistry and astrophysics. It aims at enhancing our understanding of the radiative properties of hot gaseous media to allow for improved analysis and interpretation of the large mass of data available on the thousands of exoplanets and exoplanetary systems known to date. Our approach is to use theoretical research validated by laboratory experiments and to then inject it into models of the atmospheres of the giant gaseous planets in the solar system and other planetary systems.…

First Applications of New Methane Linelists to the Modelling of Titan's Spectrum in the 1.58 and 1.28 Micron Windows

Application of new methane linelists to Cassini and Earth-based data of Titan

International audience

Methane line parameters in the HITRAN2012 database

International audience; The compilation of methane molecular line parameters was updated to include new global analyses and measurements for 12CH4, 13CH4 and 12CH3D. Over 70% of the methane parameters in HITRAN2008 were replaced; existing parameters retained were the microwave lines and the Dyad of 13CH4 near 7 μm and ν6 of 13CH3D near 8.7 μm, 12CH3D (7-4076 cm-1), hot bands of 12CH4 (1887-3370 cm-1) and normal sample CH4 (4800-5550 cm-1 and 8000-9200 cm-1). With a minimum intensity at 296 K in units of cm-1/(molecule cm-2) set to 10-37 for the far-IR and 10-29 for the mid- and near-IR, the methane database increased from 290,091 lines in HITRAN2008 to 468,013 lines, and three-fourths of th…

Titan's organic chemistry : a planetary-scale laboratory to study primitive Earth

Saturn?s largest satellite, Titan, has been revealed by extended ground-based and space observations, and recently by the Cassini-Huygens mission. Titan?s atmosphere hosts a complex organic chemistry in the solar system starting with nitrogen and methane and leading to the formation of hydrocarbons and nitriles, including prebiotic molecules. The atmosphere also contains traces of oxygen compounds. This system is subject to seasonal variations and different physical, dynamic, and photochemical processes. Interactions between the atmosphere, the surface, and the interior also play an important role in the astrobiological potential of the satellite.

Applications of a new set of methane line parameters to the modeling of Titan's spectrum in the 1.58 μm window

International audience; In this paper we apply a recently released set of methane line parameters (Wang et al., 2011) to the modeling of Titan spectra in the 1.58 mu m window at both low and high spectral resolution. We first compare the methane absorption based on this new set of methane data to that calculated from the methane absorption coefficients derived in situ from DISR/Huygens (Tomasko et al., 2008a; Karkoschka and Tomasko, 2010) and from the band models of Irwin et al. (2006) and Karkoschka and Tomasko (2010). The Irwin et al. (2006) band model clearly underestimates the absorption in the window at temperature-pressure conditions representative of Titan's troposphere, while the Ka…