Study reveals ‘cake-like’ lunar surface structure near Chandrayaan 3 landing site

A new scientific study has revealed that the lunar surface near the Chandrayaan-3 landing site has a layered, 'cake-like' internal structure, with distinct h...

What Happened

A new scientific study has revealed that the lunar surface near the Chandrayaan-3 landing site has a layered, 'cake-like' internal structure, with distinct horizontal strata of different composition and density beneath the surface regolith.
The study used data from Chandrayaan-3's instruments — including the Chandra's Surface Thermophysical Experiment (ChaSTE) and seismic/radar data — to characterise subsurface structure at the Moon's south polar region.
Researchers found multiple regolith layers recording a series of impact events from surrounding craters, suggesting the surface is a composite of ejecta deposited over billions of years.
The findings have direct implications for future lunar In-Situ Resource Utilisation (ISRU) and the search for water ice, which is theorised to exist in the permanently shadowed regions near the south pole.
India became the first country to soft-land near the lunar south pole when Vikram lander touched down on 23 August 2023.

Static Topic Bridges

Chandrayaan-3 Mission Overview

Chandrayaan-3 was India's third lunar exploration mission, launched by ISRO on 14 July 2023 aboard the LVM3-M4 rocket from Sriharikota. It comprised a Lander (Vikram), a Rover (Pragyan), and a Propulsion Module.

Landing: 23 August 2023, at approximately 69.36°S, 32.34°E — near the lunar south pole
India became the 4th country to soft-land on the Moon (after USSR, USA, China) and the 1st to do so near the south pole
Mission duration: ~14 Earth days (one lunar day), after which instruments went into sleep mode
Vikram Lander payloads:
ChaSTE (Chandra's Surface Thermophysical Experiment): Measured thermal properties of lunar regolith — first in-situ thermal profile at lunar south polar region
ILSA (Instrument for Lunar Seismic Activity): Recorded 250+ seismic signals; ~50 remain unexplained probable natural moonquakes — first seismic data from lunar south pole
RAMBHA-LP (Radio Anatomy of Moon Bound Hypersensitive ionosphere and Atmosphere): First-ever in-situ measurements of near-surface lunar plasma at the south pole; detected low-density plasma with 5–30 million electrons per cubic meter
Pragyan Rover payloads:
LIBS (Laser-Induced Breakdown Spectroscope): Detected aluminum, calcium, iron, chromium, titanium, manganese, silicon, oxygen, and confirmed unambiguous presence of sulphur — first in-situ sulphur detection at lunar south pole
APXS (Alpha Particle X-ray Spectrometer): Elemental analysis of lunar soil

Connection to this news: The new study builds on Chandrayaan-3's foundational measurements to model the 3D subsurface structure, revealing the stratified 'cake-like' architecture that earlier orbital data could not resolve.

Lunar Regolith and Stratigraphy

Lunar regolith is the layer of loose, fragmented material covering solid bedrock on the Moon. Unlike Earth's soil, it is formed primarily by meteorite impacts, cosmic ray bombardment, and solar wind interaction over billions of years — there is no weathering by water or wind.

Regolith thickness at the Chandrayaan-3 landing site region: estimated 1.1–7.0 m (based on analogous south pole data from related missions)
Deeper weathered material extends to ~40 m in the south polar region
Layers in the regolith record successive impact ejecta from craters including Manzinus and Schomberger, and the ancient South Pole-Aitken (SPA) basin
South Pole-Aitken basin: One of the largest and oldest impact craters in the solar system (~2,500 km diameter); its formation contributed much of the deep-excavated material to the regolith in the south polar region
The layered structure (analogous to geological stratigraphy on Earth) provides a time-ordered record of impact history

Connection to this news: The 'cake-like' stratification described in the study is consistent with this impact-driven deposition model — each layer represents a distinct period of ejecta deposition from regional impacts.

In-Situ Resource Utilisation (ISRU) and Lunar South Pole Significance

ISRU refers to the use of resources found at a mission destination (rather than carried from Earth) to support human or robotic operations. The lunar south pole is of particular interest because of the potential presence of water ice in permanently shadowed craters.

Water ice at the south pole can be used for: drinking water for astronauts, oxygen generation, hydrogen fuel for rockets — enabling sustainable lunar bases
Permanently Shadowed Regions (PSRs) near the south pole receive no direct sunlight; temperatures can drop below -200°C, preserving volatile compounds
Understanding subsurface layering is critical for deciding where and how deep to drill for ice extraction
NASA's Artemis program, ESA, and ISRO's Chandrayaan-4 (planned) all target the south polar region for this reason
Chandrayaan-3's confirmed sulphur detection and thermal profile data help constrain models of ice distribution and regolith mining feasibility

Connection to this news: The layered structure found in this study directly informs ISRU planning — knowing the depth and composition of each regolith layer is essential for designing drilling and resource extraction equipment.

ISRO's Space Programme — Context for UPSC

ISRO was established in 1969; headquartered in Bengaluru
Operates under the Department of Space, under the Prime Minister's Office
India's Space Policy 2023 opened the sector to private players through IN-SPACe (Indian National Space Promotion and Authorisation Centre)
Chandrayaan series: Chandrayaan-1 (2008) — confirmed water molecules on Moon; Chandrayaan-2 (2019) — orbiter operational, lander crash-landed; Chandrayaan-3 (2023) — successful south pole landing
Chandrayaan-4 (planned): Sample return mission to lunar south pole

Key Facts & Data

Chandrayaan-3 landing date: 23 August 2023 (celebrated as National Space Day in India)
Landing site coordinates: ~69.36°S, 32.34°E (lunar south polar region)
India is the 1st country to land near the lunar south pole
Sulphur confirmed in-situ by Pragyan rover's LIBS instrument — first such detection at lunar south pole
ILSA recorded 250+ seismic signals; ~50 are probable natural moonquakes
RAMBHA-LP measured plasma density of 5–30 million electrons per cubic meter
South Pole-Aitken basin diameter: ~2,500 km — among the largest impact structures in the solar system
Chandrayaan-3 mission cost: approximately ₹615 crore (~$75 million) — significantly lower than comparable international missions