The Iogenic SO tex2html_wrap_inline35 Source During the Galileo Flyby of Io

M. L. Marconi, W. H. Smyth (Atmospheric and Environmental Research)

Galileo in its December 7, 1995 encounter with Io flew through the magnetospheric wake caused by the satellite, with a closest approach altitude of  900 km. Magnetospheric instruments were able to sample the Iogenic plasma source in Io's vicinty where the plasma pickup rate should be strongly concentrated. Here we present results for the SO tex2html_wrap_inline35 density along the spacecraft trajectory calculated with the AER neutral cloud model which utilizes a realistic flux distribution for the Iogenic neutral source, a Voyager based torus plasma description, and takes into account the temporal variation of the torus plasma over the period of interest. The resulting SO tex2html_wrap_inline35 density is compared with a lower bound to the SO tex2html_wrap_inline35 inferred by Huddlestone et al. (1997) who interpreted 2 to 3 sec magnetic field fluctuations as ion cyclotron waves generated by freshly produced SO tex2html_wrap_inline35 ions and related the amplitude of these waves to the density of SO tex2html_wrap_inline35 . We provide estimates of SO tex2html_wrap_inline47 source rates at Io's exobase and SO tex2html_wrap_inline35 source rates in the magnetosphere

Huddlestone, D. E., R. J. Strangeway, J. Warnecke, C. T. Russell, and M. G. Kivelson, Ion Cyclotron Waves Observed at Gailieo's Io Encounter. Warm Plasma Dispersion Analysis. Geophys. Res. Letts., in press, 1997.