Extension of the frequency range of thermal impedance measurements for the characterization of the thermophysical properties of regolith

An effective approach for the extension of the frequency range of a miniaturized thermoprobe for the measurement of the thermophysical properties of regolith is proposed. The thermoprobe inserted into the regolith measures its thermal impedance in the frequency domain to infer the thermal conductivity and thermal diffusivity. The frequency extension is based on improved modeling of the heat transfer inside the sensor head and through the supporting structure of the thermoprobe. A Finite Element Method tool has been used to model this transfer function. The thermophysical properties of nine different samples including glass microbeads and the Enhanced Mojave Mars Simulant have been estimated. The results are compared with the reference values measured by a dual-probe heat-pulse standard analyzer at room atmospheric conditions. Errors below 8% for thermal conductivity and below 7% for thermal diffusivity have been observed. The proposed approach represents a very important reliability improvement, since it allows decreasing the minimum measurement frequency by a factor of 10, allowing to capture the most representative part of the thermal impedance spectra, and thus making a far more robust measurement. • A method to extend the frequency range of a thermoprobe for regolith is proposed. • The thermoprobe reliably retrieves regolith thermal properties via frequency methods. • Tests use regolith simulants: glass microbeads and Enhanced Mojave Mars Simulant.