Chandrayaan-3 “Hop” Experiment

Recent findings from a study published by ISRO in May 2026 have shed new light on the lunar surface’s structure, thanks to the pioneering “hop” experiment performed by the Chandrayaan-3 Vikram lander.

The “Hop” Maneuver

On September 2, 2023, the Vikram lander successfully executed a controlled “hop,” reigniting its engines to lift off approximately 50 cm and landing about 30–40 cm from its original position. While primarily intended to test the lander’s re-ignition capabilities—a critical skill for future sample-return missions—the maneuver provided an unexpected scientific windfall.

Scientific Breakthroughs

The engine exhaust acted like a blower, stripping away the top 3 cm of loose lunar dust (regolith) and exposing the subsurface layers.  

• Layered Stratigraphy: The moon’s surface at the South Pole is not a uniform pile of dust; rather, it exhibits a distinct, “cake-like” two-layer structure within the top few centimeters.
• Geotechnical Variability: The soil becomes significantly denser and more cohesive with depth. At the surface, the regolith is loose and “fluffy,” but at a depth of just 6.5 cm, its bulk density increases drastically (from 750 to 1600 $kg/m^3$), and it becomes much stiffer, behaving more like damp clay than dry flour.
• Thermal Dynamics: Using the Chandra’s Surface Thermophysical Experiment (ChaSTE), scientists were able to observe how the lunar surface cools during the “twilight transition.” They captured data showing a sharp temperature drop after 17:00 local time, as the absence of an atmosphere allows heat to radiate rapidly into space once the Sun’s rays are blocked by local shadows.

Why This Matters

These findings, led by the Physical Research Laboratory (PRL), are essential for future lunar exploration. Understanding the heterogeneous nature of the regolith is vital for:

• Habitat Construction: Knowing the physical strength and thermal insulation properties of the soil helps in planning for lunar bases.
• Resource Extraction: The porous, cohesive upper layers may play a significant role in the storage of water-ice molecules.
• Future Missions: Confirming that the surface can be “excavated” or altered by lander plumes helps engineers design more resilient hardware for missions involving take-offs and landings on the Moon.

This study underscores the value of in-situ experiments in the lunar polar region, confirming that even small-scale maneuvers can provide high-value data for humanity’s return to the Moon.

Source: ISRO