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Scientists at the (PRL) have discovered that the geochemical composition of the landing site, , closely resembles , the first meteorite identified as having a lunar origin, found in Antarctica in 1981-82. Using data from the 's (APXS), researchers found the landing site shares a rare composition of high magnesium and iron with lower aluminium, suggesting both represent a specific type of magnesium-rich lunar crust. This finding provides crucial insights into the moon's early formation, specifically supporting the hypothesis.
This discovery highlights the success of ISRO's Chandrayaan-3 mission in returning high-quality, actionable scientific data. The Pragyan rover, equipped with the Alpha Particle X-ray Spectrometer (APXS), provided in-situ elemental analysis of the lunar surface at Shiv Shakti Point (69.37°S, 32.32°E), a region previously unexplored. By comparing this data with 66 known lunar meteorites, scientists established the geochemical link with ALHA 81005. This emphasizes the importance of planetary missions in ground-truthing data derived from meteorites. For UPSC Prelims, understanding the function of payloads like APXS (which measures the elemental composition of rocks and soil using X-ray fluorescence) and the significance of the landing site coordinates is crucial.
The geological analysis of the lunar regolith at Shiv Shakti Point reveals a complex mixture of materials, significantly altering our understanding of lunar stratigraphy. The presence of higher olivine-to-pyroxene ratios compared to typical lunar highland regions, alongside fragments of magnesium-rich rocks, suggests the soil contains material excavated from deeper layers of the moon's crust. This is likely due to the site's proximity (~350 km) to the massive South Pole-Aitken (SPA) basin, one of the largest known impact craters in the solar system. The SPA basin-forming event likely dredged up deeper mantle material, distributing it across the southern high latitudes. This mechanism of impact cratering and ejecta distribution is a key concept in planetary geology, relevant for Mains questions on lunar formation and evolution.
The findings strongly corroborate the Lunar Magma Ocean (LMO) hypothesis. This theory posits that the early moon was entirely molten, and as it cooled, different minerals crystallized and separated based on density. Lighter minerals (like plagioclase) floated to form the primary crust (the anorthositic highlands), while denser, iron-and-magnesium-rich minerals sank to form the mantle. The discovery of primitive, mantle-related materials (Mg-suite rocks) at the surface of Shiv Shakti Point suggests complex processes, perhaps significant impacts or later volcanic activity, brought these deeper materials to the surface. The rare compositional space occupied by both the site and the meteorite—between ferroan anorthosites (FAN) and Mg-suite rocks—provides critical evidence for refining models of the moon's early differentiation and thermal history.