Green, J. L., W. W. Taylor, S. F. Fung, R. F. Benson, W. Calvert, B.
W. Reinisch, D. L. Gallagher, and P. Reiff, Radio remote sensing of
magnetospheric plasmas, Chapman Conference on Measurement Technique
for Space Plasmas, Santa Fe, New Mexico, April 3-7, 1995.

Radio remote sensing of magnetospheric plasmas

James L. Green, William W. L. Taylor, Shing F. Fung, Robert F. Benson,
Wynne Calvert, Bodo Reinisch, Dennis Gallagher, and Patricia Reiff

With recent advances in radio transmitter and receiver design, and modern
digital processing techniques it should be possible to perform remote radio
sounding of the magnetosphere utilizing methods perfected for ionospheric
sounding over the last two decades.  Like ionospheric sounding, free-space
electromagnetic waves, launched within a low density region will reflect at
remote plasma cutoffs.  The location and characteristics of the plasma at the
remote reflection point can then be derived from measurements of the delay
time, frequency, and direction of an echo.  A magnetospheric radio sounder,
operating at frequencies between 3 kHz to 3 MHz could provide quantitative
electron density profiles simultaneously in several different directions on a
time scale of minutes or less.  The test of this technique will not have to
wait long, since the first magnetospheric radio sounder will fly on the
Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) mission to be
launched in the year 2000.  A simulation of radio remote sensing of the
magnetosphere from the IMAGE orbit, reported here, was accomplished by
using ray tracing calculations combined with specific radio sounder
instrument characteristics.  The radio sounder technique should provide a
truly exciting opportunity to study global magnetospheric dynamics in a way
which was never before possible.