Magnetospheric Sounding on IMAGE James L. Green The Radio Plasma Imager (RPI) on the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) spacecraft was designed as a long-range magnetospheric radio sounder, relaxation sounder, and a passive plasma wave instrument. The RPI is a highly flexible instrument that can be programmed to perform these types of measurements at times when IMAGE is located in key regions of the magnetosphere. The echoes observed by RPI are analyzed to obtain electron densities profiles all along the sounder ray paths allowing a comprehensive picture of the structure and dynamics of the inner magnetosphere to be created. _______________ Proceedings of the 7th International School for Space Simulations, Kyoto University, March 26-31, 2005.