Cassini Visual and Infrared Mapping Spectrometer Observations of Iapetus: Detection of CO2
B. J. Buratti
(1)
,
Dale P. Cruikshank
(2)
,
Robert H. Brown
(3)
,
Roger N. Clark
(4)
,
James M. Bauer
(1)
,
Ralf Jaumann
(5)
,
Thomas B. Mccord
(6)
,
D. P. Simonelli
(1)
,
C. A. Hibbitts
(7)
,
Gary B. Hansen
(7)
,
Tobias C. Owen
(8)
,
Kevin H. Baines
(1)
,
Giancarlo Bellucci
(9)
,
Jean-Pierre Bibring
(10)
,
Fabrizio Capaccioni
(9)
,
Priscilla Cerroni
(9)
,
Angioletta Coradini
(9)
,
Pierre Drossart
(11, 12, 13)
,
Vittorio Formisano
(9)
,
Yves Langevin
(10)
,
Dennis L. Matson
(1)
,
Vito Mennella
(9)
,
Robert M. Nelson
(1)
,
Philip D. Nicholson
(14)
,
Bruno Sicardy
(11, 12, 13)
,
Christophe Sotin
(15)
,
Ted L. Roush
(2)
,
K. Soderlund
(1)
,
A. Muradyan
(1)
1
JPL -
Jet Propulsion Laboratory
2 National Aeronautics and Space Administration, Ames Research Center
3 LPL - Lunar and Planetary Laboratory [University of Arizona]
4 US Geological Survey, Denver
5 Institute for Planetary Exploration, Deutsches Zentrum for Luft und Raumfahrt
6 Planetary Geoscience Division, Institute of Geophysics and Planetology,
7 Planetary Science Institute, 225 South Lake Avenue
8 Institute for Astronomy, University of Hawaii
9 Institute di Fisica dello Spazio Interplanetario, CNR
10 IAS - Institut d'astrophysique spatiale
11 Observatoire de Paris
12 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
13 Pôle Planétologie du LESIA
14 Department of Astronomy, Cornell University
15 LPG - Laboratoire de Planétologie et Géodynamique [UMR 6112]
2 National Aeronautics and Space Administration, Ames Research Center
3 LPL - Lunar and Planetary Laboratory [University of Arizona]
4 US Geological Survey, Denver
5 Institute for Planetary Exploration, Deutsches Zentrum for Luft und Raumfahrt
6 Planetary Geoscience Division, Institute of Geophysics and Planetology,
7 Planetary Science Institute, 225 South Lake Avenue
8 Institute for Astronomy, University of Hawaii
9 Institute di Fisica dello Spazio Interplanetario, CNR
10 IAS - Institut d'astrophysique spatiale
11 Observatoire de Paris
12 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
13 Pôle Planétologie du LESIA
14 Department of Astronomy, Cornell University
15 LPG - Laboratoire de Planétologie et Géodynamique [UMR 6112]
Résumé
The Visual and Infrared Mapping Spectrometer (VIMS) instrument aboard the Cassini spacecraft obtained its first spectral map of the satellite Iapetus in which new absorption bands are seen in the spectra of both the low-albedo hemisphere and the H2O ice-rich hemisphere. Carbon dioxide is identified in the low-albedo material, probably as a photochemically produced molecule that is trapped in H2O ice or in some mineral or complex organic solid. Other absorption bands are unidentified. The spectrum of the low-albedo hemisphere is satisfactorily modeled with a combination of organic tholin, poly-HCN, and small amounts of H2O ice and Fe2O3. The high-albedo hemisphere is modeled with H2O ice slightly darkened with tholin. The detection of CO2 in the low-albedo material on the leading hemisphere supports the contention that it is carbon-bearing material from an external source that has been swept up by the satellite's orbital motion.