Australe Basin & Chandrayaan-1 [Prelims Bits]

15 Sep 2026

Tags: Prelims   Current events of national and international importance

Source: The Indian Express

• Physical Research Laboratory (PRL), Ahmedabad researchers identified the Australe Basin on the Moon using mineralogical data from Chandrayaan-1.
• It may be older than the South Pole–Aitken (SPA) Basin, currently regarded as the largest and oldest known lunar impact basin.

Australe Basin

• Located in the southeastern hemisphere of the Moon, near the South Polar region.
• Ancient basin became difficult to detect because of erosion of its rims.
• Shows distinctive morphological, gravity and mineralogical signatures.
• Contains 248 small basalt ponds arranged in a circular pattern.
• Its basalts are relatively low in calcium and high in magnesium, unlike most lunar basalts.

Impact Basins

• Formed by major asteroid/meteorite impacts on the lunar surface.
• Much larger than ordinary impact craters; may extend hundreds of kilometres.
• Often possess outer rims and impact-related ejecta, and may subsequently contain volcanic/basaltic deposits.
• Around 300 impact basins are estimated on the Moon, but only about 74 had been identified according to the study cited.

South Pole–Aitken Basin

• Located on the far side of the Moon, spanning the southern polar region.
• Largest and oldest known lunar impact basin, formed over 4 billion years ago.
• Its enormous age makes it important for understanding the early history of the Moon and Solar System.

Chandrayaan-1 & Moon Mineralogy Mapper

• Chandrayaan-1: India's first lunar mission; launched in 2008.
• Carried 11 scientific payloads, including 6 from international space agencies.
• Moon Mineralogy Mapper (M³): imaging spectrometer contributed by NASA, used to map lunar surface mineralogy.
• Operated in the 405–3000 nanometre wavelength range.
• Detects mineral signatures through characteristic spectral absorption bands.

Significance

• Material excavated by the Australe impact may have been transported towards the lunar South Pole.
• Helps interpret the geological evolution of South Polar regions and identify potentially valuable sites for future lunar sample-return missions.
• Relevant to proposed Chandrayaan-4 and future international lunar exploration.
• Basalt is a dark, fine-grained volcanic rock formed from rapidly cooled lava; lunar maria are largely composed of basaltic plains.
• Olivine, pyroxene and plagioclase are major minerals used to study the composition and geological evolution of the Moon.