Dielectric measurements and radar attenuation estimation of ice/basalt sand mixtures as martian Polar Caps analogues

The nature of the materials underlying the superficial deposits of Mars can be inferred, applying an inversion algorithm, from the data acquired by the orbiting HF radars MARSIS and SHARAD. This approach requires the knowledge of the electromagnetic properties of the shallow deposits and an accurate evaluation of the signal attenuation. The present work is focused on the determination of the dielectric parameters of several geo-materials. We performed the measurements of the complex permittivity, in a wide range of temperature (150–250 K) and frequency (20 Hz–1 MHz), on pure water ice, dry basalt sand and ice/basalt mixtures with different sand volume fractions. The data are presented in terms of attenuation as a function of basalt volume fraction, frequency and temperature, and discussed in terms of extrapolation to MARSIS and SHARAD frequency bands. The results show that, besides the expected dependence of the attenuation from temperature, the presence of the solid inclusions in the ice strongly affects the behaviour of the attenuation versus frequency.