Density, Temperature and Frequency Dependent Model of the Dielectric Map of Martian Surface
Résumé
We report on laboratory electromagnetic characterization of several hyper-dry synthesized and field collected Mars analog soils that match the type of soils identified by the TES [1] and OMEGA [2] on the Martian surface in order to experimentally investigate the dielectric properties of the sediments covering the Martian surface at the frequency range from 1 to 1000 MHz. Measurements were performed as a function of the density and temperature, hence increasing the degree of complexity associated with the dependency of the surface dielectric properties on these surface environmental parameters. The density ranged from 0.8 to 2.4 gcm-3, covering the density range of the Martian surface dust as deduced from TES thermal inertial data. Due to instrumentational constraint we were only able to vary the temperature range from 22 to -73 °C. Measurements were performed on three types of samples: (1) synthetic mixtures of Mars-like soils that were prepared with the addition of varying amounts of hematite, magnetite and maghemite to pure silica sand; (2) field collected basaltic rocks with a well defined mineralogy and petrology from potential terrestrial Mars-analog sites; (3) dirty ice with different concentration of Martian dust. Those parametric measurements are integrated to form updated models of the surface dielectric map of Mars that consider the effect of variations in the surface density and temperature.