HR: 1340h
AN: P43A-0954    [Abstracts]
TI: Thermal Plasma Flow Near Enceladus: Evidence for the `Missing' Water Source?
AU: * Tokar, R L
EM: rlt@lanl.gov
AF: Los Alamos National Laboratory, Space Science and Applications, Los Alamos, NM 87545 United States
AU: Sittler, E C
EM: Edward.C.Sittler@nasa.gov
AF: NASA Goddard Space Filght Center, Laboratory for Solar and Space Physics, Greenbelt, MD 20771 United States
AU: Johnson, R E
EM: rej@virginia.edu
AF: University of Virgina, Engineering Physics and Astronomy, Charlottesville, VA 22904 United States
AU: Thomsen, M F
EM: mthomsen@lanl.gov
AF: Los Alamos National Laboratory, Space Science and Applications, Los Alamos, NM 87545 United States
AU: Crary, F J
EM: Fcrary@swri.edu
AF: Souhtwest Research Institute, Space Science and Engineering, San Antonio, TX 78230 United States
AU: Young, D T
EM: dyoung@swri.edu
AF: Souhtwest Research Institute, Space Science and Engineering, San Antonio, TX 78230 United States
AU: Hill, T W
EM: hill@rice.edu
AF: Rice Universtiy, Department of Physics and Astronomy, Houston, TX 77001 United States
AU: Coates, A J
EM: ajc@mssl.ucl.ac.uk
AF: University College London, Mullard Space Science Laboratory, Surrey, RH5 6NT United Kingdom
AU: Gurnett, D A
EM: donald-gurnett@uiowa.edu
AF: University of Iowa, Department of Physics and Astronomy, Iowa City, IA 52242 United States
AU: Baragiola, R A
EM: raul@virginia.edu
AF: University of Virgina, Engineering Physics and Astronomy, Charlottesville, VA 22904 United States
AU: Burger, M H
EM: burger@aura.astro.Virginia.EDU
AF: University of Virgina, Engineering Physics and Astronomy, Charlottesville, VA 22904 United States
AB: On July 14, 2005, the Cassini spacecraft made a close encounter with Saturn's satellite Enceladus, passing within about 175 km of the surface. During this encounter, the Cassini Plasma Spectrometer (CAPS) observed a deflection in the co-rotating plasma flow along with a decrease in flow speed, commencing at least 20 RE (RE = Enceladus radius = 249 km) before closest approach to the satellite. The goal in this study is to use these CAPS data, along with other CAPS data within the E-ring, but far from Enceladus, to investigate the relative magnitude of the E-ring and Enceladus as sources of neutrals and plasma. Cassini Radio and Plasma Wave Science (RPWS) estimates of the total electron density will be used to constrain CAPS data where appropriate. Mass-loading calculations, like that used by Sittler et al. [2004] for a model Enceladus atmosphere, along with the plasma parameters presented in Sittler et al. [2005] for the SOI period, will be used to estimate background plasma parameters. The model atmosphere will be adjusted to match the spatial description of the mass loading determined from the CAPS data during the Enceladus encounter. The resulting model atmosphere will be compared with other Cassini data and estimates of the neutral and plasma source rate to Saturn's magnetosphere will be calculated. This analysis will be combined with models for the surface source rate to determine whether or not the missing source of water for the neutral OH torus (Jurac et al, 2002) is water vapor directly emitted from the surface of Enceladus. 1. Sittler et al., Pickup ions at Dione and Enceladus: Cassini Plasma Spectrometer simulations, JGR, vol. 109, A01214, 2004. 2. Sittler et al., Preliminary results on Saturn's inner plasmasphere as observed by Cassini: Comparison with Voyager, GRL, vol. 32, L14S07, 2005. 3. Jurac, S. et al. Saturn: Search for the missing water source. GRL 29, 2172, 25-1-4 doi:10.1029/2002GL015855,2002.
DE: 5737 Magnetospheres (2756)
DE: 6275 Saturn
DE: 6280 Saturnian satellites
SC: Planetary Sciences [P]
MN: Fall Meeting 2005