Estimation of subsurface dielectric target depth for GPR planetary exploration: Laboratory measurements and modeling

• Ground penetrating radar for detecting subsurface targets in planetary exploration
• Laboratory scale experiment in a “sand box” setup
• Accurate location of a shallow buried rock in Martian soil simulant
• Numerical simulations for laboratory measurement validation

In order to test the accuracy of Ground Penetrating Radar (GPR) in the detection of subsurface targets for planetary exploration, a laboratory scale experiment is performed based on a ‘sand box’ setup using two different bistatic GPR commercial instruments. Specific attention is paid to the challenging case of buried dielectric scatterers whose location and dimensions are of the same order of magnitude of the GPR antenna separation and signal wavelengths. The target depth is evaluated by using the wave propagation velocity measured with Time Domain Reflectometry (TDR). By means of a proper modeling of the different wave-propagation contributions to the gathered signal, the position of buried targets is correctly estimated with both GPRs even for rather shallow and small-size scatterers in near-field conditions. In this frame, relevant results for a basalt block buried in a silica soil are discussed. The experimental configuration is also simulated with an ad-hoc numerical code, whose synthetic radar sections fully confirm the measured results. The acquired information is of paramount importance for the analysis of various scenarios involving GPR on-site application in future space missions.