Application of ionospheric topside-sounding results to magnetospheric physics and astrophysics



[1] A brief review is presented to illustrate how the knowledge and experience gained from investigations of ionospheric topside-sounder ionograms has benefited scientific research beyond the ionosphere. In particular, to the interpretation of (1) natural radio emissions from space plasmas, (2) sounder-stimulated echoes and plasma emissions, and plasma diagnostics in planetary magnetospheres and (3) X-ray spectra of disks around neutron stars and black holes. The relevant data are from 60 satellite years of ionospheric topside-sounder operations by the four satellites of the International Satellites for Ionospheric Studies (ISIS) program from 1963 through 1989. Not all of these data were reduced to ionograms on 35-mm film. An ongoing effort at the NASA Goddard Space Flight Center is producing digital topside-sounder ionograms directly from a selected subset of the original telemetry tapes. More than 300,000 digital ionograms are now in the National Space Science Data Center at the NASA GSFC (