Vikram’s ‘jump’ unlocks surface ‘layers’ near lunar south pole region

BENGALURU: When India’s lunar lander Vikram briefly lifted off and returned to the moon in 2023, it marked a small but significant moment in the Chandrayaan-3 mission. Now, brief “jumps” lasting about three minutes are helping scientists piece together what’s beneath the moon’s surface using very fine measurements.A maneuver near the end of the mission moved the lander about half a meter, giving researchers a rare opportunity to study a nearby patch of untouched ground and compare it to the original landing site.After the lander stabilized, a key instrument on the lander, a temperature probe called ChaSTE (Chandra Surface Thermophysics Experiment), was pushed into the soil again. This time, only five of the ten sensors managed to penetrate the ground, as the new location was on a slightly steeper slope inside a small crater. Even so, it documented how heat moves across the ground during a brief window before sunset — about a lunar hour of observation, with some gaps due to mission constraints.The findings come from a study led by K Durga Prasad of the Physical Research Laboratory (PRL) and published in The Astrophysical Journal.The results show that the moon’s surface is not uniform. Instead, it consists of layers that behave differently. The top few centimeters form a layer that conducts heat more easily, while the material underneath is less conductive. This layered structure changes the way the surface heats up during the day and cools down at night.The jump itself also changes the ground. When Vikram started the engine, the force seemed to blow away the top 3 centimeters or so of soil, exposing the denser material below. In effect, the lander inadvertently “digged” the surface without using a drill. Interestingly, this local perturbation within half a meter was unexpected – soil properties are usually uniform over such short distances.This reveals another key feature. As depth increases, the soil becomes more compact. Near the surface it is loose and porous, but within just a few centimeters it becomes denser and more compact. This change affects the stability of the lander and rover ground. The measurements are also significantly different from data found in equatorial regions by the Apollo and Surveyor missions decades ago, suggesting that the polar regions have their own unique characteristics.The detector also tracked temperature changes during dusk. As the sunlight fades, the ground gradually cools, and then the temperature drops dramatically. The upper layer reacts faster than the lower layer, again indicating structural differences.The significance of these findings extends beyond this single experiment. The Chandrayaan-3 landing site is located in the south pole region of the moon, an area of ​​interest because it may contain frozen water. Understanding how heat moves through soil can help scientists estimate where this ice may exist and remain stable.The study also shows the sensitivity of the lunar surface. Even a brief engine ignition can change the top layer enough to expose what’s underneath. Future missions, especially those aimed at collecting samples or building infrastructure, will need to take this effect into account.Ultimately, the jump, which lasted about three minutes, provided a clearer image of the moon’s surface, showing that even tiny movements can yield valuable scientific clues.