HR: 15:10h
AN: P52B-07    [PDF]
TI: The Plasma Environments of Jupiter's Galilean Satellites - Galileo Radio Science Results
AU: * Kliore, A J
EM: akliore@jpl.nasa.gov
AF: Jet Propulsion Laboratory California Institute of Technology, 4800 Oak Grove Dr, Pasadena, CA 91109 United States
AB: The Galileo spacecraft has been orbiting Jupiter since 1995. During that time it has provided several opportunities for the study of the plasma environments of the Galilean satellites Io,Europa, Ganymede, and Callisto by means of radio occultation of its S-band (13.5 cm. wavelength) signal. There have been five occultations each by Io, Europa, Ganymede, and Callisto, however, one of the Ganymede and one of the Callisto occultations occurred near superior conjunction, and did not provide useful data. When observed, the maximum electron densities range from about 5 to about 20x10$^{3}$ cm$^{-3}$ . The apparent vertical structure of these plasma layers range from classical ionospheric profiles observed at Callisto on two occasions to multi-peaked structures observed at Europa. On several occasions no discernible plasma was observed. These observations could be explained by a process in which a tenuous neutral atmosphere ( about 10$^{10}$ cm$^{-3}$ is created on the trailing hemisphere by sputtering from the icy surface by energetic particles of the Jovian magnetosphere. If the trailing hemisphere is also illuminated by the Sun, plasma is produced by photoionization and is observed by radio occultation. The configuration of this plasma is, however, determined by its interaction with the corotating Jovian magnetospheric plasma, which under certain geometries would lead to the observation of multipeaked structures.
DE: 2431 Ionosphere/magnetosphere interactions (2736)
DE: 2459 Planetary ionospheres (5435, 5729, 6026, 6027, 6028)
DE: 6028 Ionospheres--structure and dynamics
DE: 6218 Jovian satellites
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting