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The Atmospheres of Saturn and Titan in the Near-Infrared: First Results of Cassini/VIMSThe wide spectral coverage and extensive spatial, temporal, and phase-angle mapping capabilities of the Visual Infrared Mapping Spectrometer (VIMS) onboard the Cassini-Huygens Orbiter are producing fundamental new insights into the nature of the atmospheres of Saturn and Titan. For both bodies, VIMS maps over time and solar phase angles provide information for a multitude of atmospheric constituents and aerosol layers, providing new insights into atmospheric structure and dynamical and chemical processes. For Saturn, salient early results include evidence for phosphine depletion in relatively dark and less cloudy belts at temperate and mid-latitudes compared to the relatively bright and cloudier Equatorial Region, consistent with traditional theories of belts being regions of relative downwelling. Additional Saturn results include (1) the mapping of enhanced trace gas absorptions at the south pole, and (2) the first high phase-angle, high-spatial-resolution imagery of CH4 fluorescence. An additional fundamental new result is the first nighttime near-infrared mapping of Saturn, clearly showing discrete meteorological features relatively deep in the atmosphere beneath the planet's sunlit haze and cloud layers, thus revealing a new dynamical regime at depth where vertical dynamics is relatively more important than zonal dynamics in determining cloud morphology. Zonal wind measurements at deeper levels than previously available are achieved by tracking these features over multiple days, thereby providing measurements of zonal wind shears within Saturn's troposphere when compared to cloudtop movements measured in reflected sunlight. For Titan, initial results include (1) the first detection and mapping of thermal emission spectra of CO, CO2, and CH3D on Titan's nightside limb, (2) the mapping of CH4 fluorescence over the dayside bright limb, extending to approximately 750 km altitude, (3) wind measurements of approximately 0.5 ms(exp -1), favoring prograde, from the movement of a persistent (multiple months) south polar cloud near 88 deg S latitude, and (4) the imaging of two transient mid-southern-latitude cloud features.
Document ID
20080032388
Acquisition Source
Jet Propulsion Laboratory
Document Type
Reprint (Version printed in journal)
Authors
Baines, K. H.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Drossart, P.
(Observatoire de Paris-Meudon France)
Momary, T. W.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Formisano, V.
(Consiglio Nazionale delle Ricerche Rome, Italy)
Griffith, C.
(Arizona Univ. Tucson, AZ, United States)
Bellucci, G.
(Consiglio Nazionale delle Ricerche Rome, Italy)
Bibring, J. P.
(Paris Univ. Paris, France)
Brown, R. H.
(Arizona Univ. Tucson, AZ, United States)
Buratti, B. J.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Capaccioni, F.
(Consiglio Nazionale delle Ricerche Rome, Italy)
Cerroni, P.
(Consiglio Nazionale delle Ricerche Rome, Italy)
Clark, R. N.
(Geological Survey Denver, CO, United States)
Coradini, A.
(Consiglio Nazionale delle Ricerche Rome, Italy)
Combes, M.
(Centre National de la Recherche Scientifique Meudon, France)
Cruikshank, D. P.
(Centre National de la Recherche Scientifique Meudon, France)
Jaumann, R.
(NASA Ames Research Center Moffett Field, CA, United States)
Langevin, Y.
(Paris Univ. Paris, France)
Matson, D. L.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
McCord, T. B.
(Deutsche Forschungsanstalt fuer Luft- und Raumfahrt Cologne, Germany)
Mennella, V.
(Washington Univ. Washington, DC, United States)
Nelson, R. M.
(Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Nicholson, P. D.
(Deutsche Forschungsanstalt fuer Luft- und Raumfahrt Cologne, Germany)
Sicardy, B.
(Observatoire de Paris-Meudon France)
Sotin, C.
(Cornell Univ. Ithaca, NY, United States)
Date Acquired
August 24, 2013
Publication Date
June 1, 2005
Publication Information
Publication: Earth, Moon, and Planets
Publisher: Springer
Volume: 96
ISSN: 0167-9295
Subject Category
Lunar And Planetary Science And Exploration
Distribution Limits
Public
Copyright
Other
Keywords
Cassini Mission
Saturn
Visual Infrared Mapping Spectrometer (VIMS)
atmospheric structure
Titan

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