The Chandrayaan-3 mission, belonging to India, has come out with milestone discoveries: once, the southern pole of Earth’s satellite was covered by an ocean of molten rock. That will support the Lunar Magma Ocean theory, according to which the surface of the Moon was wholly molten soon after its formation some 4.5 billion years ago.
The Chandrayaan-3 mission, which landed on the Moon on August 23, 2023, deployed a rover called Pragyan that was supposed to head into this yet unexplored territory. Through ten days of its operation, Pragyan was able to gather data that ranged from thermal readings to seismological readings. But its most important contribution would turn out to be from studying the chemical makeup of the lunar regolith, the fine material covering much of the Moon’s surface.
Now, Pragyan’s alpha-particle X-ray spectrometer alone made 23 measurements, returning data showing that the regolith composition at the south pole is mostly of ferroan anorthosite. A key mineral to corroborate the indication that the lunar surface was once a molten magma ocean. “It’s sort of what we expected to be there based on orbital data, but ground truth is always really good to get,” said Lindy Elkins-Tanton, a planetary scientist at Arizona State University.
The Chandrayaan-3 findings assume extra importance since they are the first from the subpolar region of the Moon. All earlier missions, including the Apollo program, had covered areas ranging from the equatorial to mid-latitude zones. This uniformity in regolith composition across these different regions further strengthens the hypothesis that the entire lunar surface was once molten.
According to Santosh Vadawale of the Physical Research Laboratory in Ahmedabad, India, an X-ray astronomer, this was supported by high levels of magnesium in the samples, which showed that deeper mafic material must have mixed up into the regolith. He added that such mixing could have been caused by the creation of the South Pole–Aitken basin, a large crater formed by the impact of a meteorite about four billion years ago. “When such a large impact basin forms, it is supposed to excavate some deeper material,” Vadawale noted.
However, the presence of magnesium-rich material poses a puzzle. The South Pole–Aitken basin is dominated by pyroxene, a mineral that doesn’t quite match Pragyan’s data. Bringing samples back to Earth for more detailed analysis could resolve this discrepancy, a goal for India’s next lunar mission planned for 2025 or 2026.
Besides, the Chandrayaan-3 mission will have the task of verifying whether there is ice water on the south pole of the moon. This could be a life-changing discovery for subsequent lunar exploration or even building a human base on the moon. “To me, it’s a story about the success of the Indian space program,” says Elkins-Tanton, looking at the bigger picture.
This, therefore, sums up Chandrayaan-3 as compelling proof for the Lunar Magma Ocean theory and opens up new avenues toward the understanding of the geological history of the Moon and future exploration potential.