Chandrayaan-1 data has revealed mineralogical evidence supporting an ancient lunar impact basin that is no longer visible through topographic or gravity observations.

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• A study published in The Planetary Science Journal in August 2026 identified mineralogical evidence supporting the ancient Australe Basin on the Moon.
• Researchers analysed Chandrayaan-1 data and examined orthopyroxene distribution, a mineral associated with material excavated during massive lunar impacts.
• Orthopyroxene-bearing spectral signatures predominantly follow the circular boundary of Mare Australe basalts, indicating a previously obscured geological structure.
• The study states that orthopyroxene distribution delineates the boundary of the obliterated Australe Basin, providing mineralogical evidence for its existence.
• Unlike visible topographic or gravity signatures, mineralogical patterns preserved beneath younger geological formations can reveal evidence of ancient lunar impacts.
• The findings demonstrate how Chandrayaan-1 observations continue contributing valuable information about the Moon’s geological history and ancient impact processes.
• The Australe Basin appears to represent an ancient impact structure whose physical signatures have been substantially erased from conventional lunar datasets.
• The discovery highlights the importance of mineralogical mapping for identifying ancient lunar structures that remain difficult to detect through surface topography.
• Orthopyroxene provides an important geological indicator because large impacts can excavate material originating from deeper crustal or mantle regions.
• Chandrayaan-1’s spectral observations therefore offer researchers another method for reconstructing major impact events that shaped the Moon’s ancient surface.