Ahmedabad: A lunar meteorite recovered from Antarctica more than four decades ago has now been linked to India’s Chandrayaan-3 landing site through a shared geochemical signature, according to a Physical Research Laboratory (PRL) study published in NPJ Space Exploration.In 1981, scientists collecting meteorites in the Allan Hills region of Antarctica identified fragments later catalogued as ALHA 81005 — widely regarded as the first meteorite conclusively proven to have originated from the moon. A new analysis reports that ALHA 81005 most closely matches the elemental composition measured in situ at “Shiv Shakti Statio”, the Chandrayaan-3 landing site where the Vikram lander touched down in 2023 and the Pragyan rover conducted surface investigations.The paper, titled “Chandrayaan-3 APXS measurements reveal lunar highland compositional diversity and meteorite connections”, is authored by Dwijesh Ray, Rishitosh K Sinha, Santosh V Vadawale, M Shanmugam and Anil Bhardwaj.Ray said the rover’s Alpha Particle X-ray Spectrometer (APXS) measurements point to a distinctive chemistry at the site. “The soil analysis by Alpha Particle X-ray Spectrometer (APXS) aboard Pragyan Rover of Chandrayaan 3 exhibits an elevated magnesium number (Mg# 70), higher than the average value reported for the Feldspathic Highland Terrane, giving the site a distinctive geochemical signature,” he said.Sinha said the overlap with ALHA 81005 is not limited to a single parameter. “Both Shiv Shakti Statio and ALHA 81005 exhibit comparable abundances of aluminium, iron and magnesium, elevated magnesium number (Mg#), and occupy a rare compositional space between ferroan anorthosite and Mg-suite rocks,” he said.The researchers compared Chandrayaan-3 APXS readings with geochemical data from 66 feldspathic lunar meteorites collected from Oman, Libya, Northwest Africa, Northeastern Africa, Southern Africa and Antarctica. Among the meteorites evaluated, the study reports that ALHA 81005 emerged as the closest compositional match, supporting the inference that both the meteorite and the Chandrayaan-3 site sample a similar magnesium-rich feldspathic crust within the lunar highlands.PRL Director Anil Bhardwaj placed the findings in the context of long-term lunar research. “It has given us an insight into the composition of the moon as an entity shaped by billions of years of impact and geological processes,” he said.Scientists have been keenly watching the nearside southern high-latitude highlands because the area is believed to include material brought up by large impacts. The study notes Chandrayaan-3’s measurements showed a relatively high olivine-to-pyroxene ratio and elevated magnesium content, consistent with possible contributions from lower crust and upper mantle materials. It adds that basin-forming events — cited as the South Pole Aitken (SPA) basin — may have helped bring deeper material closer to the surface, where rover instruments can measure it.
