Space-Borne Radio Sounding of the Ionosphere and Magnetosphere and other adventures during 6 decades since leaving the Geophysical Institute

This presentation will focus mainly on research based on data from the 4 ionospheric topside-sounder satellites Alouette 1 & 2 and ISIS I & II of the International satellites for Ionospheric Studies (ISIS) program, and from the Radio Plasma Imager (RPI) on the IMAGE satellite (Imager for Magnetopause-to-Aurora Global Exploration). The 4 Alouette/ISIS satellites produced 60 satellite-years of analog data collected between 1962 and 1990. Many of the records (ionograms) from Alouette 2 and ISIS I & II have been converted to digital files and are available from https://spdf.gsfc.nasa.gov/isis/isis-status.html. IMAGE was launched on 25 March 2000 and was operational for nearly 6 years (https://ulcar.uml.edu/rpi.html). These space-borne radio sounders have enabled (1) a wealth of global electron-density information on the topside ionosphere and magnetosphere based on vertical and magnetic field-aligned electron-density profiles, (2) accurate in-situ electron-density values even under low-density conditions, (3) proper identification of natural ionospheric and magnetospheric radio emissions, (4) information on the departure of magnetospheric electron-velocity distributions from Maxwellian, (5) fundamental advances in our understanding of the excitation and propagation of plasma waves, and (6) observational support for a predicted new plasma wave mode.