The study, led by a joint research team organised by the China National Space Administration (CNSA), has been published in the latest issue of the journal Science, Xinhua news agency reported.
BEIJING — A new study of the lunar samples collected by China's Chang'e-6 mission has verified the hypothesis that the Moon was entirely covered by a molten "magma ocean" in the early stages after its birth, providing critical evidence for understanding the Moon's origin and evolution.
This study, led by a joint research team organised by the China National Space Administration (CNSA), has been published in the latest issue of the journal Science, Xinhua news agency reported.
The Chang'e-6 mission in 2024 accomplished humanity's first-ever sampling from the far side of the Moon, successfully retrieving 1,935.3 grams of lunar materials from the Apollo Basin within the South Pole-Aitken (SPA) Basin.
The research team from the Institute of Geology, Chinese Academy of Geological Sciences, was granted two grams of these Chang'e-6 samples to conduct their research. The study revealed that the composition of basalt, a type of volcanic rock, from both the far and near sides of the Moon proved similar.
The basalt present in the Chang'e-6 samples is primarily 2.823 billion years old, and its characteristics support the lunar magma ocean model. The research also suggests that the impact event that created the SPA Basin may have altered the Moon's early mantle, according to Liu Dunyi, a senior researcher at the institute.
The lunar magma ocean model was previously established based on samples from the Moon's near side. The model proposes that the newborn Moon went through a global melting event, creating a vast magma ocean.
As this ocean cooled and crystallised, less dense minerals floated to the surface to form the lunar crust, while denser minerals sank to form the mantle.
The remaining melt, enriched with incompatible elements, formed the KREEP layer, with the name derived from the initials of the key components, namely potassium (K), rare earth elements (REE), and phosphorus (P), Dunyi explained.
However, for decades, all lunar samples came from the Moon's near side, leaving the model incomplete.
"Without samples from the far side, it was like solving a puzzle with half the pieces missing," said Dunyi, while adding that the far-side samples collected by Chang'e-6 had changed this scenario.
"Our analysis showed that the KREEP layer exists on the Moon's far side as well. The similarity in basalt composition between the far and near sides indicates that a global magma ocean may have spanned the entire Moon," added Che Xiaochao, an associate researcher at the institute.
The SPA Basin, where Chang'e-6 landed, is no ordinary crater. Stretching 2,500 km, which is comparable to the distance from Beijing to south China's Hainan, and plunging to a depth of 13 km, this colossal scar, formed by a cataclysmic asteroid impact 4.3 billion years ago, is the oldest and largest impact basin in the inner solar system, according to scientists.