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Moon analyzed by Chang’e 6 indicates that carbonaceous asteroids arrived later to the Earth-Moon system, limiting possible delivery of water from Earth by ancient impacts, according to a Chinese study released on May 12, 2026, with samples from the lunar far side and new data on space bombardments of the Solar System.
The Moon has once again revealed clues about the Earth’s ancient history. In a study released on May 12, 2026, Chinese scientists used samples collected by the Chang’e 6 mission to identify a significant change in the types of asteroids that bombarded the Earth-Moon system between 4.3 billion and 2.8 billion years ago.
According to the site China Daily, the discovery indicates a transition: initially, non-carbonaceous asteroids, linked to the inner Solar System, predominated; later, carbonaceous asteroids, rich in water and organic matter, appeared in greater proportion. This delay may change how scientists evaluate the arrival of water to the primitive Earth.
Moon samples function as a record of ancient collisions
For scientists, the Moon records part of the history of impacts that hit the Solar System over the last 4 billion years. Unlike Earth, which had its surface deeply modified by tectonic plates, erosion, water, and geological activity, the satellite preserves ancient marks with more stability.
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It was precisely for this reason that the Chang’e 6 samples attracted so much attention. The mission brought soil from the lunar far side, allowing researchers to analyze fragments that carry traces of collisions that occurred in different periods.
The team isolated 40 impact clasts, small fragments formed in violent events, containing tiny metallic particles. These grains function as time capsules because they preserve information about the bodies that hit the Moon in the remote past.
The importance lies not only in the lunar material itself but in what it tells about Earth’s neighborhood. By studying the satellite, scientists can reconstruct part of the bombardment that also affected our planet.
Researchers separated ancient and more recent fragments
The analysis of the 40 fragments allowed the samples to be divided into two groups. The first group is linked to basaltic debris, associated with impacts recorded in the last 2.8 billion years, after basaltic eruptions on the lunar surface.
The second group comes from anorthosites of the lunar highlands, older materials ejected from other regions of the Moon. These fragments preserve impact events that may date back 4.3 billion years.
This separation was essential because it allowed for the comparison of different periods in the history of the Earth-Moon system. Instead of looking at impacts as a single, uniform event, researchers observed how asteroid types changed over time.
The result showed that ancient bombardment did not always have the same composition. There was a significant change between the objects that hit the region in more remote phases and those that arrived later.
Carbonaceous asteroids appear later in the lunar record
In the 13 oldest clasts, the metals found corresponded mainly to ordinary chondrites and iron meteorites, materials associated with the inner Solar System. In this group, metals from carbonaceous asteroids represented less than 8%.
In the 27 younger clasts, the proportion of metals from carbonaceous asteroids rose to approximately 26%. This jump indicates that these bodies began to contribute more to impacts between 4.3 billion and 2.8 billion years ago.
This change is significant because carbonaceous asteroids are known to contain water and organic matter. For a long time, they were seen as possible important deliverers of water to early Earth.
However, the study suggests that this arrival was delayed. If these water-rich asteroids appeared in greater numbers when the impact flux was already lower, the total amount of water delivered may have been more limited than previously thought.
Discovery challenges part of the hypothesis about Earth’s water
The hypothesis that carbonaceous asteroids helped bring water to Earth remains important, but gains a new nuance with the Chang’e 6 data. The central point is the timing of these bodies’ arrival in the Earth-Moon system.
According to the study’s interpretation, water-rich and volatile asteroids began to appear in greater proportion after a phase when impacts had already decreased significantly. This reduces the possibility that they delivered volumes as large as some previous hypotheses suggested.
By comparing fragments of different ages, scientists used the Earth-Moon system as a reference to measure when carbonaceous asteroids began to appear more prominently. This reading suggests that Earth’s water may have a more complex origin, as the delivery by late impacts might have been less than some previous hypotheses indicated.
The Moon, in this case, functions as a historical control. If the satellite shows that the arrival of carbonaceous asteroids was later, it is possible that Earth also received less water through this path than previously thought.
This does not mean that Earth’s water has a single origin discarded or confirmed. The discovery merely reorganizes a piece of the puzzle and shows that the timing of impacts is as important as the composition of the asteroids.
Three mechanisms can explain the change in impacts
The scientific team points to three possible mechanisms to explain the observed transition. The first involves the migration of giant planets, capable of spreading carbonaceous asteroids to more inner regions of the Solar System.
The second is the so-called Yarkovsky effect, in which small thermal forces slowly alter the orbit of space bodies over time. This gradual displacement could push asteroids into trajectories that cross the Earth and Moon region.
The third mechanism would be the collision fragmentation of large carbonaceous bodies. When a larger object breaks apart, it can generate vast fields of debris, increasing the chance of some of this material reaching the Earth-Moon system.
Each hypothesis points to a different dynamic of the primitive Solar System. In common, all show that the arrival of these asteroids was neither simple nor immediate, but the result of long and complex orbital processes.
Chang’e 6 enhances the scientific importance of the lunar far side
The Chang’e 6 mission gained importance because it brought samples from a lunar region still little explored directly by material return missions. The far side of the Moon may preserve different records from those already studied in samples from other areas.
This type of material helps compare ages, compositions, and impact events in different parts of the satellite. The greater the variety of lunar samples, the more refined the reading of the inner Solar System’s history becomes.
Researcher Lin Yangting, from the Institute of Geology and Geophysics of the Chinese Academy of Sciences, highlighted that the Moon serves as a preserved archive of the Earth-Moon system’s impact history. The assessment reinforces the value of new collections in regions of different ages.
Lunar science has ceased to be just the study of the satellite and has become a window to understand the Earth itself. Each fragment analyzed can reveal something about the environment in which our planet formed and evolved.
New samples can refine the history of asteroids
The study published in the Journal of Geophysical Research: Planets shows that there is still much to be investigated. The samples from Chang’e 6 revealed a significant change, but future missions may expand the temporal map of impacts.
Collections in lunar regions of different ages can help define when carbonaceous asteroids began to arrive in greater quantity and what their real contribution was to water, volatiles, and organic matter in the inner Solar System.
This refinement can also improve models on the orbital evolution of celestial bodies. Understanding how asteroids changed course helps explain not only Earth’s past but also current risks and dynamics in near space.
In the end, the Moon returns to fulfill a silent but decisive role: keeping records that Earth lost. Do you believe that the water on our planet came mainly from asteroids, or does this discovery show that the origin may be more complex than it seemed? Share your opinion.
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