Theoretical prediction ofthe thermal conductivity and temperature variation inside mars soil analogues

Mars soil analogues, in dry and frozen conditions, are investigated, as far as the thermal conductivity prediction and the temperature variation, along its depth, are concerned. The thermal conductivity is theoretically predicted with the cubic cell model, which requires the knowledge ofthe thermal conductivity ofthe solid particle and ofthe materials present, i.e. atmospheric gas and/or frozen ice, and the porosity ofthe soil analogue. The soil mineral composition allows to evaluate the thermal conductivity ofthe solid particle. The heat capacity ofthe soil analogue is evaluated with the knowledge ofits physical properties, the porosity and the speci1c heats ofthe materials present. The thermal di2usivity is calculated as the ratio ofthe thermal conductivity and heat capacity and results to be a function ofthe porosity and the ice mass content ofthe soil analogue. The temperature variations, in dry and partially frozen soil analogues, are predicted during a Martian day. The temperature variation, at di2erent depth, is attenuated, as compared to the surface variation and a phase delay is present, depending on the soil thermal properties. The temperature variation, as well as the derivative ofthe temperature variation with the depth, is dependent on the thermal di2usivity ofthe soil analogue. In conclusion, the temperature measurement, along the depth ofa Martian soil analogue, can be used to verify its physical status, i.e. dry or partially frozen.