Samples from the far side of the moon confirm that it was once a solid ocean of magma

In the summer of 2024, China’s Chang’e-6 mission returned samples from the far side of the Moon to Earth for the first time. They were similar in some ways to samples from the visible side, but in some details they were significantly different, hinting at slightly different geological developments on the two sides of the satellite. The new work provides insight into the Moon’s volcanic past and the evolution of its mantle.

Image source: NASA

A study by scientists at the Chinese Academy of Geological Sciences, published in the journal Science, has confirmed the long-standing model of the Moon as a global ocean of liquid magma. This ocean has covered the entire surface of the satellite since its formation and has likely existed for tens to hundreds of millions of years.

After analyzing basalt fragments found at the station’s landing site, scientists discovered that these rocks have a similar composition to basalts collected on the visible side of the Moon during NASA’s Apollo missions. This discovery helps to create a more complete picture of volcanic processes on the Moon.

At the same time, some samples from the far side of the satellite differed from those obtained on its visible side. In particular, differences were observed in the ratio of certain isotopes of uranium and lead. The authors of the article believe that the chemical and physical properties of the lunar mantle in this region were changed by a giant collision, as a result of which about 4.2 billion years ago the South Pole-Aitken basin, which is approximately 2,500 km wide, was formed.

Image source: Xinhua

Initial analysis of Chang’e-6 samples has already revealed a number of differences from samples taken from the near side of the Moon, including differences in density, structure, and concentrations of characteristic chemicals. However, the research is far from complete, and future discoveries may be unsuspected by Earth science.