ISRO Detects Subsurface Ice in Lunar South Polar Craters via Chandrayaan-2 Radar

<h3>Overview</h3> <p>The <span class="key-term" data-definition="Chandrayaan-2 — India’s second lunar mission launched in <strong>July 2019</strong>, comprising an orbiter, lander and rover; significant for GS3 (Science & Technology) and GS2 (Polity) as a showcase of India’s space capability">Chandrayaan-2</span> continues to yield scientific returns six years after launch. Using its <span class="key-term" data-definition="Dual Frequency Synthetic Aperture Radar (DFSAR) — a radar payload that operates at two frequencies to generate high‑resolution images of the Moon’s surface; important for GS3 (Science & Technology) remote‑sensing studies">DFSAR</span>, scientists from the <span class="key-term" data-definition="Physical Research Laboratory (PRL) — a premier Indian research institute focusing on space and planetary sciences; relevant to GS3 (Science & Technology) for its contributions to lunar research">PRL</span> have identified radar signatures that point to possible subsurface ice in four doubly‑shadowed craters of the lunar south pole.</p> <h3>Key Developments</h3> <ul> <li>Radar analysis shows <span class="key-term" data-definition="Circular Polarization Ratio (CPR) — a radar metric that compares the circularly polarized returned signal with the transmitted one; CPR > 1 suggests volume scattering such as ice, a concept examined in GS3 (Science & Technology)">CPR</span> values > 1 together with <span class="key-term" data-definition="Degree of Polarization (DOP) — a radar parameter indicating how much of the original polarisation is retained after reflection; DOP < 0.13 helps separate ice signatures from rough terrain, relevant to GS3 (Science & Technology)">DOP</span> <strong>0.13</strong> in the studied craters.</li> <li>The most compelling evidence comes from a <strong>1.1 km</strong> crater inside the larger Faustini crater, which also displays a lobate‑rim morphology suggesting an impact into ice‑rich substrate.</li> <li>Temperatures in the examined permanently shadowed regions (PSRs) remain around <strong>‑25 K</strong>, creating conditions that can preserve water‑ice over geological timescales.</li> </ul> <h3>Important Facts</h3> <p>• <span class="key-term" data-definition="permanently shadowed regions (PSRs) — zones near the lunar poles that never receive sunlight, staying extremely cold and capable of trapping volatiles like water‑ice; important for GS3 (Science & Technology) and GS1 (Geography) studies">PSRs</span> are ideal for long‑term ice preservation.<br> • The radar‑based criterion (CPR > 1 and DOP < 0.13) provides a more reliable method to differentiate ice from rocky terrain.<br> • The findings enhance our understanding of lunar polar volatiles, a key resource for future missions.</p> <h3>UPSC Relevance</h3> <p>These results intersect with several UPSC syllabus areas. In GS3, they illustrate the application of remote‑sensing technology and the strategic importance of space exploration. In GS2, they underscore India’s policy direction under ISRO for sustainable lunar activities. The potential of <span class="key-term" data-definition="in‑situ resource utilisation (ISRU) — the practice of using local resources, such as lunar ice, to produce fuel, water or building material; crucial for GS3 (Science & Technology) and GS2 (Polity) as it reduces dependence on Earth‑supplied logistics">ISRU</span> ties directly to future crewed missions and international cooperation.</p> <h3>Way Forward</h3> <p>• Expand radar surveys to map ice distribution across the entire lunar south pole.<br> • Integrate findings with upcoming missions (e.g., Artemis, Chandrayaan‑3) to identify landing sites for ISRU experiments.<br> • Formulate policy frameworks that promote technology transfer and commercial exploitation of lunar resources, ensuring compliance with international space law.</p>