Chang'e-6 specimens offer proof of early moon's "magma ocean"
A recent study of lunar samples gathered by China's Chang'e-6 mission has confirmed the theory that the moon was entirely enveloped in a molten "magma ocean" during its formative years.
TroibNews 
A new study of the lunar samples gathered by China’s Chang’e-6 mission supports the theory that the moon was entirely enveloped by a molten "magma ocean" shortly after its formation. This finding is crucial for deepening our understanding of the moon’s origin and evolution.
The study, conducted by a collaborative research team assembled by the China National Space Administration, has been published in the most recent issue of the journal *Science*.
In 2024, the Chang’e-6 mission made history by successfully collecting 1,935.3 grams of lunar material from the far side of the moon, specifically from the Apollo Basin located within the South Pole-Aitken Basin.
Researchers from the Institute of Geology at the Chinese Academy of Geological Sciences received a two-gram sample from the Chang’e-6 mission for their analysis.
The findings indicated that the composition of basalt—a type of volcanic rock—was largely similar on both the far and near sides of the moon. The basalt samples from Chang’e-6 are primarily 2.82 billion years old, and their features lend support to the lunar magma ocean model. Additionally, it was noted that the impact that formed the SPA Basin may have transformed the moon's early mantle, as explained by Liu Dunyi, a senior researcher at the institute.
The lunar magma ocean theory was initially based on samples from the moon’s near side, suggesting that the early moon underwent a melting event that created a vast magma ocean. As this ocean cooled, less dense minerals rose to the surface, forming the lunar crust, while denser minerals sank to create the mantle. The remaining melt, rich in incompatible elements, resulted in the formation of the KREEP layer, with the name derived from the initials of its key components: potassium, rare earth elements, and phosphorus, according to Liu.
However, for many years, lunar samples were exclusively collected from the near side, leaving gaps in the model. "Without samples from the far side, it was like solving a puzzle with half the pieces missing," Liu remarked, highlighting how the far-side samples from Chang’e-6 have altered this understanding.
"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," stated Che Xiaochao, an associate researcher at the institute.
The site of the Chang’e-6 landing, the SPA Basin, is significant. Measuring 2,500 kilometers across—similar to the distance from Beijing to south China's Hainan—and reaching a depth of 13 kilometers, this massive crater formed by a catastrophic asteroid impact approximately 4.3 billion years ago is the oldest and largest impact basin in the inner solar system, according to scientists.
Interestingly, the study also uncovered that the lead isotope evolution paths in the basalt samples from the far and near sides differ. This indicates varying evolutionary processes across different lunar regions after the magma ocean crystallized. Long Tao, another senior researcher on the team, noted that massive impact events, particularly the one that created the SPA Basin, likely altered the physical and chemical properties of the moon's mantle.
"In other words, the moon was once covered by a global magma ocean, but later bombardments of asteroids caused different evolution processes on the near and far sides," Long elaborated.
The research team intends to further explore the moon’s early impact history. "The Chang’e-6 sampling site is in the largest and oldest impact basin in the inner solar system, so it may contain records useful for the study of early solar system impacts," Che mentioned. "We also hope to find materials from the moon's mantle."
"Studying the moon's impact history helps us understand Earth's own past, which has been obscured by tectonic activities," Long added.
The CNSA reiterated its dedication to advancing lunar research and disseminating scientific discoveries with the global community.
Rohan Mehta for TROIB News
The study, conducted by a collaborative research team assembled by the China National Space Administration, has been published in the most recent issue of the journal *Science*.
In 2024, the Chang’e-6 mission made history by successfully collecting 1,935.3 grams of lunar material from the far side of the moon, specifically from the Apollo Basin located within the South Pole-Aitken Basin.
Researchers from the Institute of Geology at the Chinese Academy of Geological Sciences received a two-gram sample from the Chang’e-6 mission for their analysis.
The findings indicated that the composition of basalt—a type of volcanic rock—was largely similar on both the far and near sides of the moon. The basalt samples from Chang’e-6 are primarily 2.82 billion years old, and their features lend support to the lunar magma ocean model. Additionally, it was noted that the impact that formed the SPA Basin may have transformed the moon's early mantle, as explained by Liu Dunyi, a senior researcher at the institute.
The lunar magma ocean theory was initially based on samples from the moon’s near side, suggesting that the early moon underwent a melting event that created a vast magma ocean. As this ocean cooled, less dense minerals rose to the surface, forming the lunar crust, while denser minerals sank to create the mantle. The remaining melt, rich in incompatible elements, resulted in the formation of the KREEP layer, with the name derived from the initials of its key components: potassium, rare earth elements, and phosphorus, according to Liu.
However, for many years, lunar samples were exclusively collected from the near side, leaving gaps in the model. "Without samples from the far side, it was like solving a puzzle with half the pieces missing," Liu remarked, highlighting how the far-side samples from Chang’e-6 have altered this understanding.
"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," stated Che Xiaochao, an associate researcher at the institute.
The site of the Chang’e-6 landing, the SPA Basin, is significant. Measuring 2,500 kilometers across—similar to the distance from Beijing to south China's Hainan—and reaching a depth of 13 kilometers, this massive crater formed by a catastrophic asteroid impact approximately 4.3 billion years ago is the oldest and largest impact basin in the inner solar system, according to scientists.
Interestingly, the study also uncovered that the lead isotope evolution paths in the basalt samples from the far and near sides differ. This indicates varying evolutionary processes across different lunar regions after the magma ocean crystallized. Long Tao, another senior researcher on the team, noted that massive impact events, particularly the one that created the SPA Basin, likely altered the physical and chemical properties of the moon's mantle.
"In other words, the moon was once covered by a global magma ocean, but later bombardments of asteroids caused different evolution processes on the near and far sides," Long elaborated.
The research team intends to further explore the moon’s early impact history. "The Chang’e-6 sampling site is in the largest and oldest impact basin in the inner solar system, so it may contain records useful for the study of early solar system impacts," Che mentioned. "We also hope to find materials from the moon's mantle."
"Studying the moon's impact history helps us understand Earth's own past, which has been obscured by tectonic activities," Long added.
The CNSA reiterated its dedication to advancing lunar research and disseminating scientific discoveries with the global community.
Rohan Mehta for TROIB News
