HR: 08:50h
AN: SH41C-04 INVITED     [Abstracts]
TI: Time varying south polar atmosphere on Enceladus from magnetic field measurements analyzed by use of 3D two-fluid plasma simulations
AU: * Saur, J
EM: joachim.saur@jhuapl.edu
AF: Institute f. Geophysics and Meteorology, University of Cologne, Cologne, 50923 Germany
AU: Neubauer, F M
EM: fmneubauer@t-online.de
AF: Institute f. Geophysics and Meteorology, University of Cologne, Cologne, 50923 Germany
AU: Dougherty, M K
EM: m.dougherty@imperial.ac.uk
AF: Institute f. Geophysics and Meteorology, University of Cologne, Cologne, 50923 Germany
AU: Dougherty, M K
EM: m.dougherty@imperial.ac.uk
AF: Blackett Laboratory, Imperial College, London, SW7 2AZ United Kingdom
AU: Khurana, K K
EM: kkhurana@igpp.ucla.edu
AF: Institute of Geophysics and Planetary Physics, UCLA, LA, 90095 United States
AU: Russell, C T
EM: ctrussel@igpp.ucla.edu
AF: Institute of Geophysics and Planetary Physics, UCLA, LA, 90095 United States
AB: Cassini spacecraft magnetic field measurements from three Enceladus flybys in February, March and July 2005 present a unique possibility to explore the existence and to quantitatively determine properties of a neutral atmosphere around the satellite. The magnetic field measurements from the first ever close spacecraft encounters with Enceladus provide evidence for a dynamical neutral cloud originating from Enceladus south pole. We study for the first time the magnetic field measurements with a series of physically consistent three-dimensional two fluid plasma simulations where we vary density, location and extension of a neutral cloud originating from Enceladus. The magnetic field measurements of the March and July flybys are inconsistent with a globally extended Enceladus centered atmosphere, but are indicative of a spatially confined neutral plume which originates near Enceladus south pole. The March flyby occurred south of the equator and upstream of the satellite around closest approach. The July flyby was also upstream, but along a trajectory strongly varying in south-north direction. The first Cassini flyby in February (upstream, north of the equator) demonstrates the time variability of Enceladus atmosphere. This flyby is consistent with an Alfven wing structure that is created by a spatially extended atmosphere that might, however, still be constrained to Enceladus southern hemisphere.
DE: 6005 Atmospheres (1060)
DE: 6030 Magnetic fields and magnetism
DE: 6280 Saturnian satellites
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005