Measurements of Dielectric Discontinuities in Planetary Subsurfaces with a Passive Instrument

Abstract:

Global Navigation Satellite Systems Reflectometry (GNSS-R) has shown that passive sensing that takes advantage of separate active sources can be used to infer the soil moisture, snow pack depth and other quantities of scientific interest. Here we take that concept one step further and propose a passive measurement of the sub-surface dielectric profile of Mars by taking advantage of the multipath interference between reflections off the surface and subsurface dielectric discontinuities. Previous studies have shown that this technique is capable of detecting changes in the sub-surface dielectric constant, but here we present the first experimental data showing that it can detect multilayer subsurface profiles. We have measured layered beds of sand and concrete and compared these experimental results to a numerical model of the signal reflections; showing that dielectric discontinuities in the subsurface can be measured using this passive sensing technique. The exciting thing about this technique is the ability to conduct ground penetrating radar measurements in the shallow subsurface of planetary bodies without active radar transmitters.