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Cassini Ion and Neutral Mass Spectrometer: Enceladus Plume Composition and Structure
J. Hunter Waite, Jr.,1Michael R. Combi,1Wing-Huen Ip,2Thomas E. Cravens,3Ralph L. McNutt, Jr.,4Wayne Kasprzak,5Roger Yelle,6Janet Luhmann,7Hasso Niemann,5David Gell,1Brian Magee,1Greg Fletcher,1Jonathan Lunine,6,8Wei-Ling Tseng2
The Cassini spacecraft passed within 168.2 kilometers of thesurface above the southern hemisphere at 19:55:22 universaltime coordinated on 14 July 2005 during its closest approachto Enceladus. Before and after this time, a substantial atmosphericplume and coma were observed, detectable in the Ion and NeutralMass Spectrometer (INMS) data set out to a distance of over4000 kilometers from Enceladus. INMS data indicate that theatmospheric plume and coma are dominated by water, with significantamounts of carbon dioxide, an unidentified species with a mass-to-chargeratio of 28 daltons (either carbon monoxide or molecular nitrogen),and methane. Trace quantities (<1%) of acetylene and propanealso appear to be present. Ammonia is present at a level thatdoes not exceed 0.5%. The radial and angular distributions ofthe gas density near the closest approach, as well as otherindependent evidence, suggest a significant contribution tothe plume from a source centered near the south polar cap, asdistinct from a separately measured more uniform and possiblyglobal source observed on the outbound leg of the flyby.
1 Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, MI 48109, USA. 2 Institutes of Astronomy and Space Science, National Central University, Chung Li 32054, Taiwan. 3 Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045, USA. 4 Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723, USA. 5 NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA. 6 Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA. 7 Space Science Laboratory, University of California, Berkeley, CA 94720, USA. 8 Istituto di Fisica dello Spazio Interplanetario, Via del Fosso del Cavaliere 100, 00133 Rome, Italy.
From the Cover: Unified model of tectonics and heat transport in a frigid Enceladus.
G. Gioia, P. Chakraborty, S. Marshak, and S. W. Kieffer (2007)
PNAS
104, 13578-13581
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The Variable Rotation Period of the Inner Region of Saturn's Plasma Disk.
D. A. Gurnett, A. M. Persoon, W. S. Kurth, J. B. Groene, T. F. Averkamp, M. K. Dougherty, and D. J. Southwood (2007)
Science
316, 442-445
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A Clathrate Reservoir Hypothesis for Enceladus' South Polar Plume.
S. W. Kieffer, X. Lu, C. M. Bethke, J. R. Spencer, S. Marshak, and A. Navrotsky (2006)
Science
314, 1764-1766
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Cassini observes the active south pole of Enceladus..
C. C. Porco, P. Helfenstein, P. C. Thomas, A. P. Ingersoll, J. Wisdom, R. West, G. Neukum, T. Denk, R. Wagner, T. Roatsch, et al. (2006)
Science
311, 1393-1401
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Cassini encounters Enceladus: background and the discovery of a south polar hot spot..
J. R. Spencer, J. C. Pearl, M. Segura, F. M. Flasar, A. Mamoutkine, P. Romani, B. J. Buratti, A. R. Hendrix, L. J. Spilker, and R. M. C. Lopes (2006)
Science
311, 1401-1405
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Identification of a dynamic atmosphere at Enceladus with the Cassini magnetometer..
M. K. Dougherty, K. K. Khurana, F. M. Neubauer, C. T. Russell, J. Saur, J. S. Leisner, and M. E. Burton (2006)
Science
311, 1406-1409
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The interaction of the atmosphere of Enceladus with Saturn's plasma..
R. L. Tokar, R. E. Johnson, T. W. Hill, D. H. Pontius, W. S. Kurth, F. J. Crary, D. T. Young, M. F. Thomsen, D. B. Reisenfeld, A. J. Coates, et al. (2006)
Science
311, 1409-1412
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Cassini dust measurements at Enceladus and implications for the origin of the E ring..
F. Spahn, J. Schmidt, N. Albers, M. Horning, M. Makuch, M. Seiss, S. Kempf, R. Srama, V. Dikarev, S. Helfert, et al. (2006)
Science
311, 1416-1418
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Enceladus' water vapor plume..
C. J. Hansen, L. Esposito, A. I. F. Stewart, J. Colwell, A. Hendrix, W. Pryor, D. Shemansky, and R. West (2006)
Science
311, 1422-1425
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Composition and physical properties of Enceladus' surface..
R. H. Brown, R. N. Clark, B. J. Buratti, D. P. Cruikshank, J. W. Barnes, R. M. E. Mastrapa, J. Bauer, S. Newman, T. Momary, K. H. Baines, et al. (2006)
Science
311, 1425-1428
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