New findings from India’s Chandrayaan-3 mission suggest that the moon was once covered by a vast magma ocean. Analysis of geological samples collected by the mission indicates that an ocean of molten rock once engulfed the moon. On August 23, 2023, the Vikram lander successfully touched down on the lunar surface and deployed the Pragyan rover to explore the landing site, which was farther south than any previous mission.
Pragyan’s measurements revealed that the lunar soil around the landing site is primarily composed of a white rock type called ferroan anorthosite. This chemical composition is similar to samples collected by the Apollo 16 mission and the Soviet Union’s Luna-20 mission, despite being from distant locations on the moon. This supports the theory that a global magma ocean once existed on the moon early in its history.
The study’s findings, published in *Nature*, show uniformity in the lunar surface composition over several meters, providing valuable “ground-truth” data to compare with previous orbital measurements from Chandrayaan-1 and -2. These results give new confidence in the orbital datasets and help in interpreting lunar meteorites, which offer samples from various parts of the moon.
The lunar magma ocean model, first proposed after the Apollo 11 mission, suggests that as the magma ocean cooled, dense minerals sank to form the mantle, while lighter ferroan anorthosite floated to form the moon’s crust. However, the study also found higher concentrations of magnesium in the crust than expected, indicating a more complex composition that may include material from underlying layers mixed during impact cratering.
These findings help to build a more detailed picture of the moon’s geological history and the formation of its crust. The Chandrayaan-3 landing site, likely covered by ejected material from the massive South Pole-Aitken impact basin, provides a unique insight into the moon’s early history.
