Chandrayaan-2 detects possible presence of subsurface ice near south pole of moon

📌 Summary:

• Nearly six years after launch, India's Chandrayaan-2 orbiter has detected the possible presence of subsurface ice near the lunar south pole — a major finding by scientists at the Physical Research Laboratory (PRL), Ahmedabad

• The study used data from the orbiter's Dual Frequency Synthetic Aperture Radar (DFSAR), an L-band (12 cm) and S-band (24 cm) radar payload that can penetrate several metres below the lunar surface and is sensitive to buried ice deposits

• Scientists focused on doubly shadowed craters — small craters located inside larger Permanently Shadowed Regions (PSRs) near the south pole, where temperatures stay below –160°C and any water-ice deposited over billions of years is preserved

• The radar signatures returned high circular polarisation ratios — a tell-tale indicator of buried ice rather than rough rocky regolith

• Significance: confirms growing evidence (from Chandrayaan-1's Moon Mineralogy Mapper, NASA's LCROSS impact, ISRO's Chandrayaan-3 lander) that the lunar south pole hosts exploitable water-ice — critical for future crewed missions, in-situ resource utilisation (ISRU), and propellant generation

🎯 UPSC Relevance: GS3 — Awareness in the fields of Space; Indigenisation of technology and developing new technology; achievements of Indians in science and technology

📝 Prelims Facts:

• Chandrayaan-2 launched 22 July 2019 by GSLV Mk III from Sriharikota; orbiter is still operational (Vikram lander crashed, but orbiter has 7+ year mission life)

• DFSAR (Dual Frequency Synthetic Aperture Radar) — built by ISRO's Space Applications Centre (SAC), Ahmedabad — first dual-frequency SAR ever flown to the Moon

• Permanently Shadowed Regions (PSRs) — crater interiors near the lunar poles that never receive direct sunlight due to the Moon's small axial tilt (~1.54°); cold-traps for water ice

• Physical Research Laboratory (PRL), Ahmedabad — autonomous research institute under DOS/ISRO; founded 1947 by Vikram Sarabhai

• Chandrayaan-3 landed near the south pole (Shiv Shakti Point, 69.37°S, 32.32°E) on 23 August 2023 — making India the first nation to land near the lunar south pole

🔑 Key Term: Doubly Shadowed Craters — small impact craters located entirely within a larger Permanently Shadowed Region; they receive no direct or even reflected/scattered sunlight, creating the coldest known places in the inner Solar System (~25–40 K) where volatile compounds, especially water ice, accumulate over geological time.