HR: 0800h
AN: P51A-1412    [Abstracts]
TI: Near-Saturn Solar Wind Speeds Determined from MIMI/ CHEMS Measurements of Pickup Ion Spectra at the Cassini Spacecraft
AU: * Hill, M E
EM: mehill@umd.edu
AF: Department of Physics, University of Maryland, College Park, MD 20742-4111 United States
AU: Hamilton, D C
EM: dch@umd.edu
AF: Department of Physics, University of Maryland, College Park, MD 20742-4111 United States
AU: Gloeckler, G
EM: gg10@umail.umd.edu
AF: Department of Physics, University of Maryland, College Park, MD 20742-4111 United States
AU: Krimigis, S M
EM: Tom.Krimigis@jhuapl.edu
AF: Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723 United States
AU: Mitchell, D G
EM: Donald.G.Mitchell@jhuapl.edu
AF: Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723 United States
AB: During the Cassini spacecraft's approach to Saturn and now while in orbit (beginning July 1, 2004), the varying energy spectrum of singly charged, $\sim$3--220 keV/e He ions is measured by the MIMI/CHEMS instrument. At these energies, He pickup ions are a significant population, well observed by CHEMS. The cutoff in pickup ion phase space densities at twice the solar wind speed provides a means to measure the speed without directly sampling the solar wind plasma; i.e., without requiring a particular orientation of the spacecraft. Since the state of the solar wind plays a fundamental role in the dynamics of the Saturnian magnetosphere, the existence of a solar wind speed monitor should contribute to a range of research efforts. We develop a method to determine the solar wind speed by fitting the pickup He spectra with a mathematical model when Cassini is in the solar wind, which is the great majority of the time. Except during periods of very low flux or passing interplanetary shocks, an automated procedure will allow routine analysis of the solar wind speed down to 1-hour resolution. The time dependent solar wind speeds that we compute will be used in conjunction with observations from other MIMI sensors to investigate energetic particle phenomena in the Saturn system.
DE: 5737 Magnetospheres (2756)
DE: 6275 Saturn
DE: 2164 Solar wind plasma
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting