RADIO SOUNDING OF THE MAGNETOSPHERE FROM A LUNAR-BASED VLF ARRAY

Using a lunar-based active radio transmitter and receiver system operating in the ''free space'' wave modes, we can obtain much information on the structures and dynamics of remote magnetospheric plasma regions in a way similar to ionosondes. Powerful, narrow-band electromagnetic pulses can be transmitted over a wide frequency range (from 10 kHz to 1 MHz). The signals would be refracted and reflected off magnetospheric structures such as the plasmapause, plasmasheet, magnetopause, and the high and low latitude boundary layers. With a series of long dipole antennas, ranging in size from 400 m to 20 lan with an output voltage ranging from 6 kV to less than 0.2 kV, a target plasma region at up to 100 R(E) can be explored. We illustrate this remote sensing technique by using the plasmasphere as a remote target, and modeling the propagations of the sounder transmitted and received pulses by ray tracing calculations.