Layering of lunar regolith at the Chandrayaan-3 landing site observed from the ChaSTE experiments from the lander

ChaSTE onboard the Vikram lander of the Chandrayaan-3 mission is designed for in-situ measurements of thermal conductivity (K) and temperature profiles of the lunar regolith with minimal disturbance. The thermal probe with 10 RTD sensors is used to measure continuous daytime lunar regolith temperature profiles to a depth of 10 cm and a 0.1 W heater foil is used to conduct heating experiments at depths of ∼4 cm and ∼8 cm. The estimated slopes from the heating curve are 3.2 K/s and 5.4 K/s at ∼8 cm and ∼4 cm, respectively. The K values determined were distinctly low ∼0.004 W/m/K at ∼4 cm depth compared to those at ∼8 cm depth (∼0.02 W/m/K) indicating layering of the lunar regolith. An exponential increase in the motor current during the probe penetration below ∼6 cm depth further substantiates the impact induced stratification of the regolith.