HR: 1340h
AN: P43A-1011 [Abstracts]
TI: Energetic Ion Precipitation at Titan
AU: * Cravens, T E
EM: cravens@ku.edu
AF: University of Kansas, Dept. of Physics and Astronomy
University of Kansas, Lawrence, KS 66045, United States
AU: Robertson, I P
EM: robertin@ku.edu
AF: University of Kansas, Dept. of Physics and Astronomy
University of Kansas, Lawrence, KS 66045, United States
AU: Ledvina, S A
EM: ledvina@ssl.berkeley.edu
AF: University of California Berkeley, Space Sciences Lab, UC Berkeley, Berkeley, CA 94720,
United States
AU: Mitchell, D G
EM: Donald.G.Mitchell@jhuapl.edu
AF: Applied Physics Lab, John Hopkins Univ., Applied Physics Lab, JHU, Laurel, MD 20723,
United States
AU: Krimigis, S M
EM: Tom.Krimigis@jhuapl.edu
AF: Applied Physics Lab, John Hopkins Univ., Applied Physics Lab, JHU, Laurel, MD 20723,
United States
AU: Waite, J H
EM: hwaite@swri.edu
AF: Southwest Research Institute, Southwest Research Institute
P.O. Drawer 28510, San Antonio, TX 78228-0510, United States
AB:
Energetic protons and oxygen ions have been observed in Saturn's outer magnetosphere and can precipitate into
Titan's atmosphere where they deposit energy and drive ionospheric chemistry. A simple model is used to
estimate ion production rates caused by the magnetospheric ion precipitation. Using an incident proton flux in
the 27 keV to 4 MeV energy interval measured by the Cassini MIMI instrument we find that significant ion
production rates exist in the 500 km to 1000 km altitude range. The electron density associated with the ion
production is estimated to be 200 - 2000 cm-3 between 500 km and 1000 km. For comparison, solar
radiation produces a dayside ionosphere with peak electron densities between about 2000 cm-3 and 6000
cm-3 . We find that energetic oxygen ions do not penetrate below about 650 km. We suggest that a few
percent of the oxygen flux is converted to negative O ions as a consequence of charge exchange collisions, which
might help to explain the negative ions observed near 1000 km by the Cassini CAPS instrument.
DE: 0343 Planetary atmospheres (5210, 5405, 5704)
DE: 2455 Particle precipitation
DE: 2459 Planetary ionospheres (5435, 5729, 6026)
DE: 2716 Energetic particles: precipitating
DE: 2732 Magnetosphere interactions with satellites and rings
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting