HR: 09:05h
AN: P51C-06 INVITED     [Abstracts]
TI: Evidence of Meteoroid Impacts on the Rings from Cassini Plasma Wave Measurements
AU: * Gurnett, D
EM: donald-gurnett@uiowa.edu
AF: University of Iowa, Dept. of Physics and Astronomy, Iowa City, IA 52242 United States
AU: Kurth, W
EM: william-Kurth@uiowa.edu
AF: University of Iowa, Dept. of Physics and Astronomy, Iowa City, IA 52242 United States
AU: Hospodarsky, G
EM: george-hospodarsky@uiowa.edu
AF: University of Iowa, Dept. of Physics and Astronomy, Iowa City, IA 52242 United States
AU: Persoon, A
EM: ann-persoon@uiowa.edu
AF: University of Iowa, Dept. of Physics and Astronomy, Iowa City, IA 52242 United States
AU: Cuzzi, J
EM: cuzzi@cosmic.arc.nasa.gov
AF: NASA/Ames Research Center, M.S. 245-3, Moffett Field, CA 94035 United States
AB: During the passage of the Cassini spacecraft through the inner region of the Saturnian system on July 1, 2004, the Radio and Plasma Wave Science (RPWS) instrument detected many impulsive narrowband emissions that appear to be closely associated with the passage over the rings. In particular, the signals began and ended at the outer edge of the A ring, and were observed almost continuously (except for data gaps) over the A and B rings, with a well-defined gap at the Cassini division. Typically the signals occur in the frequency range from about 1 to 10 kHz, with bandwidths of a few hundred Hz and durations of about 1 to 3 seconds. The peak occurrence rate was about 1 event every few seconds. A good case can be made that this radiation is propagating near the whistler-mode resonance cone, which means that the source lies on the surface of a cone extending downward centered on the magnetic field with a half-angle ranging from about 10 to 60 degrees. The impulsive character of the emission suggests that the radiation is generated by some transient energetic process in the rings. The leading candidate appears to be meteoroid impacts on the rings. Rough estimates suggest that the flux of meteoroids with radii of about 1 cm would be adequate to explain the observed occurrence rates and emission intensities.
DE: 7871 Waves and instabilities
DE: 6245 Meteors
DE: 6265 Planetary rings
DE: 6275 Saturn
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting