HR: 11:35h
AN: P52A-06    [Abstracts]
TI: The Production and Redistribution of Oxygen in Saturn's Magnetosphere: CAPS Cassini Data
AU: * Johnson, R E
EM: rej@virginia.edu
AF: University of Virginia, Engineering Physics/Astronomy, Charlottesville, VA 22904 United States
AU: Sittler, E C
AF: Goddard Space Flight Center, MC692, Greenbelt, MD 20771 United States
AU: Crary, F J
AF: Southwest Research Institute, 6220 Culebra Rd., San Antonio, TX 78228 United States
AU: Tokar, R L
AF: Los Alamos National Laboratory, MS D466, Los Alamos, NM 87545 United States
AU: Reisenfeld, D B
AF: University of Montana, Department of Physics and Astronomy, Missoula, MT 59812 United States
AU: Hill, T W
AF: Rice University, MS108, Houston, TX 77055 United States
AU: Young, D T
AF: Southwest Research Institute, 6220 Culebra Rd., San Antonio, TX 78228 United States
AU: Burger, M H
AF: University of Virginia, Engineering Physics/Astronomy, Charlottesville, VA 22904 United States
AU: Shematovich, V I
AF: Institute for Astronomy, Russian Academy of Sciences, Moscow, 119017 Russian Federation
AU: Smith, H T
AF: University of Virginia, Engineering Physics/Astronomy, Charlottesville, VA 22904 United States
AU: Michael, M
AF: University of Virginia, Engineering Physics/Astronomy, Charlottesville, VA 22904 United States
AU: Jurac, S
AF: Massachusettes Institute for Technology, MIT 37-635, Cambridge, MA 02139 United States
AU: Richardson, J D
AF: Massachusettes Institute for Technology, MIT 37-635, Cambridge, MA 02139 United States
AU: Baragiola, R A
AF: University of Virginia, Engineering Physics/Astronomy, Charlottesville, VA 22904 United States
AB: The Cassini Plasma Spectrometer (CAPS) has detected O2+, O+ and H2+ in the inner magnetosphere and over the main rings. Here we examine the formation and redistribution of molecular oxygen over the icy rings and in the inner magnetosphere. Thin oxygen atmospheres exist on Europa and Ganymede formed by radiolysis (Johnson et al. 2004). Because the escape of O2 from these satellites is inefficient,Europa has a tenuous molecular oxygen cloud (Burger and Johnson 2004, Hansen et al. 2004; Shematovich et al 2004). However, radiation induced chemistry on icy objects in Saturn's system will directly populate the magnetosphere with molecular oxygen leading to the formation of O2+ and its observed dissociation products O and O+. Therefore, in addition to neutral H (Shemansky et al. 1992), OH (Jurac et al. 2002) and nitrogen clouds(Smith et al. 2004), there is likely a molecular oxygen cloud in Saturn's magnetosphere. Since water vapor can be produced by the incident radiation, by meteoroid impacts, and by collisions between grains and small bodies, the observation of molecular oxygen can be a marker for radiation-induced decomposition of ice (Shi et al. 1995, Johnson et al. 2003). Here we present the CAPS data and calculations of the UV production of O2 and H2 over the main rings and the charged particle production over the tenuous rings. We also describe the redistribution of oxygen in Saturn's magnetosphere by ion molecule reactions and charge exchange (Eviatar et al. 1983, Johnson et al. 1989). References Burger, M.H., R.E. Johnson Icarus 171, in press 2004. Eviatar, A., et al., JGR 88, 823-831, 1983. Hansen, C. J., et al., Icarus, submitted, 2004. Johnson, R.E. et al., Astrobiology , v3, 823-850,2003. Johnson, R.E. et al., In Jupiter-The Planet, Satellites, Magnetosphere, ed. F. Bagenal et al.,Cambridge Press, 2004. Jurac, S. et al.,GRL 29, 2172, 25-1 V 4, 2002. Shematovich, V.I. et al., Icarus, in press, 2004 Shemansky, D. E., D. T. Hall. JGR 97, 4143~V4161,1992. Shi, M. et al. GRL 100 26,387-26,395, 1995. Smith, H.T., R.E. Johnson, V.I. Shematovich, GRL 31, doi:10.1029GL020580, 2004.
DE: 5421 Interactions with particles and fields
DE: 5465 Rings and dust
DE: 6265 Planetary rings
DE: 6275 Saturn
SC: Planetary Sciences [P]
MN: 2004 AGU Fall Meeting