Galileo in its December 7, 1995, encounter with Io flew downstream of Io and through the magnetospheric wake of the satellite with a closest approach altitude of ~900 km. Magnetospheric instruments were therefore able to sample the Iogenic plasma source both outside as well as deeply within the Lagrange sphere of Io (~5.81 satellite radii) where the gravity of Io dominates and where the plasma pickup processes are expected to be highly peaked about the satellite. The presence of both long-lived atomic ions (H+, O+, O++, S+, S++) and short-lived molecular ions (SO+, SO2+) was detected along the spacecraft trajectory. We have undertaken preliminary calculations for the density profile of SO2+. These calculations are compared with the SO2+ density profiles deduced from magnetic field fluctuations with periods of ~2--3 s measured by the Galileo magnetometer and interpreted as ion cyclotron waves produced by fresh SO2+ Iogenic pickup ions created near Io. By matching the absolute SO2+ model density with the minimum ion density determined by Huddleston et al. [1997> in their analysis of the ion cyclotron waves, an SO2 source rate of ~4¿1027 molecules s-1 (425 kg s-1) at Io's exobase and a corresponding SO2+ source rate of 2.8¿1026 ions s-1 (30 kg s-1) in the magnetosphere are determined. Most of the SO2 that undergoes interactions in the plasma torus is, however, rapidly dissociated primarily by electron impact, producing O, S, SO, and O2. These species subsequently undergo ionization and charge exchange reactions in the plasma torus, producing much larger mass and energy pickup plasma loading rates, including an SO+ source rate estimated to be somewhat smaller than the SO2+ source rate. Since the lifetime of SO2 is highly variable with Io's position in the plasma torus, it follows that the spatial profile for the amplitude of these magnetic fluctuations will also be highly space and time variable and will depend upon both Io System III longitude and Io geocentric phase angle. ¿ 1998 American Geophysical Union