ISRO ने Chandrayaan-2 रडार के माध्यम से चंद्र दक्षिणी ध्रुवीय क्रेटरों में सतह के नीचे बर्फ का पता लगाया

<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 pol