Thermal Imagery for Rover Soil Assessment Using a Multipurpose Environmental Chamber Under Simulated Mars Conditions

Planetary rover missions on Mars have suffered entrapments and serious mobility incidents due to soil assessment limitations of stereo RGB cameras, which cannot characterize relevant physical phenomena such as thermal behavior that depend on granularity and cohesion. In particular, thermal inertia estimations are already being used to assess geophysical properties from 1-D low-resolution measurements by onboard thermopiles. However, no high-resolution measurements are currently available to characterize Martian soils for safer navigation in future missions, so new experimental methods are required to capture and analyze thermal images with planetary conditions in Earth-based experiments. In this work, we propose a novel measurement system configuration and experimental methodology to capture thermal images using isolated multipurpose environmental chambers (MECs) to replicate the temperature and pressure conditions of Mars. Furthermore, the system has allowed to measure diurnal cycles for four soil types of known physical characteristics under Martian and Earth pressures to perform a unique quantitative analysis and comparison of thermal behavior and thermal inertia for soil assessment. Even if no actual Martian infrared (IR) images are available for comparison, results indicate a correlation between granularity and thermal inertia that is consistent with available thermopile measurements recorded by rover's onsite. Furthermore, the set of measurements acquired in the experiments has been made available to the scientific community.