Temperature variation on the wall of a driller designed for “in situ” experiments in Mars regolith

Numerical simulation of the temperature distributions along the wall of a driller, immersed in ice-free and frozen Martian regolith analogues, are carried out. The driller is made of a steel tube on the external side and a mixture of steel and Teflon internally. The cyclic temperature variations, during the Martian day, are used to evaluate the thermal diffusivity of the regolith. The measurements in two points along the wall of the driller are used for that purpose. Totally, three measuring points are employed: at the surface of the regolith, i.e. in contact with the external atmosphere, at the middle of the driller and close to the tip of the driller. The numerical simulation suggests to evaluate the thermal diffusivity of the Martian soil analogues using the average of two couples of measuring points: at the surface and the middle of the driller, at the surface and the tip of the driller. The thermal diffusivities of an ice-free regolith analogue can be predicted with an error lower than 20% and that of a frozen regolith analogue with an error of 13%.