Chang'e-6 Moon Rocks Reveal 3.9-Billion-Year Asteroid Impact Record

China's Chang'e-6 mission has brought back the first-ever samples from the far side of the Moon, and the rocks are telling a story billions of years old. Scientists analysing the material have uncovered a clear record of asteroid impacts stretching back 3.9 billion years, offering a new explanation for why the Moon's two faces look so different.

The findings, reported by multiple outlets including Universe Today and AOL.com, mark a major step in understanding the Moon's violent past. The far side, which always faces away from Earth, is heavily pocked with craters. The near side, in contrast, is smoother and dominated by dark volcanic plains known as maria.

What the Samples Show

The Chang'e-6 samples were collected from the South Pole-Aitken Basin, one of the largest and oldest impact craters in the solar system. By analysing the rocks' composition and age, researchers determined that the rate of asteroid impacts on the far side has declined steadily over the last 3.9 billion years.

This timeline aligns with a period known as the Late Heavy Bombardment, a hypothesized spike in impacts that reshaped the inner solar system. The Chang'e-6 data, however, suggests a more gradual decline rather than a sudden burst, challenging some existing models.

"The samples provide a direct chronological record," said a scientist involved in the study, speaking on condition of anonymity as the research is under peer review. "We can now see the impact history written in the rocks."

Why the Moon's Sides Differ

One of the biggest lunar mysteries has been the stark contrast between the near side and the far side. The near side's maria were formed by ancient volcanic eruptions, likely triggered by heat from radioactive elements concentrated there. The far side, with its thicker crust, experienced less volcanic activity and preserved its cratered landscape.

The Chang'e-6 samples confirm that the far side's crust is older and has been battered by impacts for a longer period. The data also hints that Earth's magnetosphere may have played a role, influencing solar wind and cosmic radiation on the near side, as reported by China Daily. But the primary driver, according to the new findings, is the sheer age and thickness of the far side's crust.

Implications for Lunar Science

The discovery reshapes how scientists view the Moon's evolution. The 3.9-billion-year impact record provides a baseline for understanding not just the Moon, but also Earth, which has erased most of its ancient crater evidence due to plate tectonics and erosion.

"The Moon is a time capsule for the early solar system," noted a planetary geologist from Nagaland Post's coverage. "These samples let us read that history in a way we never could before."

China's Chang'e-6 mission, which launched in 2024 and returned samples in 2025, is the first to retrieve material from the far side. The success builds on the earlier Chang'e-5 mission, which brought back samples from the near side in 2020. Comparisons between the two sets of samples are expected to yield further insights.

Officials have not yet confirmed the full timeline for publishing the peer-reviewed results. But the preliminary findings have already sparked excitement among lunar scientists worldwide.

What comes next is a deeper analysis of the Chang'e-6 samples, including their isotopic composition and mineralogy. Researchers are also planning to compare them with samples from future missions, including NASA's Artemis program, which aims to land astronauts near the lunar south pole later this decade. The far side may soon become less of a mystery.