36th DPS Meeting, 8-12 November 2004
Session 2 Cassini at Saturn II
Special Session, Monday, November 8, 2004, 10:30am-12:noon, Lewis

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[2.02] Imaging of Saturn's magnetosphere and energetic particles obsered during Cassini's orbit insertion at Saturn

S. M. Krimigis (Johns Hopkins University Applied Physics Lab), D. G. Mitchell (Applied Physics Lab), D. C. Hamilton (University of Maryland, College Park), N. Krupp (Max Planck Institut fuer Sonnensystemforschung, Lindau), S. Livi, E. C. Roelof (Applied Physics Lab), J. Dandouras (Centre d'Etude Spatiale Des Rayonnements, Toulouse), T. P. Armstrong (Fundamental Technologies Inc.), B. H. Mauk, C. Paranicas, P. Brandt (Applied Physics Lab), S. Bolton (Jet Propulsion Lab), A. F. Cheng, T. Choo (Applied Physics Lab), G. Gloeckler (University of Maryland), J. Hayes (Applied Physics Lab), K. C. Hsieh (University of Arizona, Tucson), W. -H. Ip (National Central University, Taiwan), S. Jaskulek, E. P. Keath (Applied Physics Lab), E. Kirsch (Max Planck Institut, Lindau), M. Kusterer (Applied Physics Lab), A. Lagg (Max Planch Institut, Lindau), L. J. Lanzerotti (Bell Laboratories), D. LaVallee (Applied Physics Lab), J. Manweiler (Fundamental Technologies Inc.), R. W. McEntire (Applied Physics Lab), W. Rasmuss (Fundamental Technologies Inc.), J. Saur, F. S. Turner, D. J. Williams (Applied Physics Lab)

The MIMI investigation comprises three sensors, the Ion and Neutral Camera (INCA), Charge-Energy-Mass-Spectrometer (CHEMS), and Low Energy Magnetospheric Measurement System (LEMMS) covering the energy ranges 7 keV/nuc < E < 200 keV/nuc (ions/neutrals), 3 < E < 230 keV/e (ions), and 0.02 < E <18 Mev (ions)/0.015 < E <1 Mev (electrons), respectively. Also, LEMMS measures high-energy electrons (E > 3 Mev) and protons (1.6 < E < 160 Mev) from the back end of the dual field-of-view telescope. The Saturn observation sequences began in January, 2004 and culminated in Saturn Orbit Insertion (SOI) on July 1, 2004. The MIMI sensors observed substantial activity in interplanetary space for several months prior to SOI, including several interplanetary shocks associated with corotating interaction regions, as well as numerous increases most likely originating from particle streams in the vicinity of the Saturnian bow shock. When the INCA sensor was switched to its energetic neutral atom (ENA) operating mode on day 51, at ~ 1000 RS (0.43 AU), a weak signal was observed denoting the presence of Saturnís magnetosphere. Results during SOI revealed a dynamical magnetosphere with a day-night asymmetry and an 11-hour periodicity; several water-product ions (O+, OH+, H2O+), but no N+; a substantial gas cloud around Titan, but little evidence of a discernible torus; and sufficient (inferred) quantities of neutral gas that cause major losses to trapped ions in the middle and inner magnetosphere. Finally, INCA imaging has revealed a previously unknown radiation belt that resides inside the D-ring that is most likely the result of double charge-exchange between the main radiation belt and the upper layers of Saturnís exosphere. The observations will be presented and discussed in the context of current theoretical models.


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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.