Region around Shiv Shakti point, where India’s Chandrayaan-3 landed, is 3.7 billion years old: study
Earth may be 4.5 billion years old but microbial life emerged some 3.7 billion years ago.
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A study by scientists of the Indian Space Research Organisation (Isro) has estimated the age of the region where the Chandrayaan-3 landing site on the moon is located to be 3.7 billion years — an age that coincides with the period when primitive microbial life first emerged on Earth.
A team of scientists from Isro’s Physical Research Laboratory (PRL), Ahmedabad, has performed morphological and topographic analysis within the Chandrayaan-3 landing site, now known as the Shiv Shakti point. On August 23, 2023, India became the first country to successfully achieve a soft landing on the moon’s south pole. With the help of data generated by the Pragyan rover housed inside the Vikram lander onboard Chandrayaan-3, Indian scientists have been uncovering new interpretations and insights into the moon’s evolution.
PRL scientists deployed high-end imaging techniques, such as the Lunar Reconnaissance Orbiter wide-angle camera and terrain camera, to gather crater and rock distribution data from the lunar surface near Shiv Shakti. They noted that the Pragyan rover encountered several rock fragments (over 1 cm in size) at the landing site. The chains of secondary craters and crater ejecta rays were used to infer the potential source of materials within the landing area. Numerous craters with three distinct terrain types were studied: high-relief rugged terrain, high-relief smooth plains, and low-relief smooth plains.
“For the low-relief smooth plains, the area that hosts the landing site, the best-fit age is about 3.7 Ga (billion years), done using 25 craters (diameter 500-1,150 metres),” the researchers said in the study. Further age estimates from another 23 craters (measuring 500-1,250 metres in diameter) with rugged terrains and an additional five craters (measuring 600-1,150 metres in diameter) with high relief and smooth plains established the age of the region to be 3.7 billion years.
The lunar surface often suffers from the combined influence of micro-meteorite bombardments and extreme thermal excursions. As a result, the exposed rock fragments in this geologically old terrain would have fragmented into regolith over the past several hundred million years, the PRL team explained.
Based on morphological interpretations, the Isro scientists concluded that the local area around the landing site was mainly formed by the ejecta of secondary craters, Manzinus and Boguslawsky.
Landing site enclosed between multiple large-impact craters
The latest study, published in the Advances in Space Research, described the regional geography around the Shiv Shakti point. The Chandrayaan-3 landing site is enclosed between multiple large-impact craters: Manzinus (diameter about 96 km, age about 3.9 billion years) to the north, Boguslawsky (diameter about 95 km, age about 4 billion years) to the southeast, and Schomberger (diameter about 86 km, age about 3.7 billion years) to the south.
The landing site is surrounded by craters Manzinus to the north, Boguslawsky to the southeast and Schomberger to the south. (Credit: PRL)
Over the years, images have helped lunar scientists globally to rebuild the history of Manzinus and Boguslawsky, with both craters appearing to have flat crater floors and subdued crater wall structures. Each of these craters is categorised as shallow, with Boguslawsky being hollower than Manzinus and Schomberger. What distinguishes the Schomberger crater is its depth and well-preserved structures — including the central peak, wall terrains, raised crater rim, and steep crater walls — along with an ejecta blanket.
Further interpretations by the PRL scientists now suggest that these large impact craters would have spewed massive ejecta in the area surrounding the landing site. Previous geological mapping had revealed significant influence of Schomberger crater secondary cratering on the terrain, about 35 km south of the landing site.
In addition, the PRL team analysed the distribution of rocks within the landing area and in the local area navigated by the Pragyan rover to identify the potential source craters for the emplacement of rocks.
Craters with three types of terrains were studied. (Credit: PRL)
“A higher rock population was concentrated near and around a morphologically fresh crater — denoted by continuous ejecta and a sharp crater rim. This fresh crater is about 14 km south of the landing site. Diagnostics of the fresh crater material revealed that it was less affected by space weathering in comparison to the surrounding area near the landing site,” the study noted.
Interestingly, about 9.1 per cent or 525 rock samples (of the total 5,764 rocks) measured more than 5 metres in length, whereas 428 rocks were situated around this fresh crater. Researchers found the two largest rock samples (measuring over 17 metres in length) in the entire landing area to be located near this fresh crater and another one close to its rim, the crater (1.8 km in diameter) located 8 km west of the landing site.
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