The giant asteroid impact 66 million years ago that killed most life on Earth and wiped out the dinosaurs has been shown to be related to lunar impacts.
A team of scientists traced 135 tiny glass beads, which were ferried back to Earth for the Chang'e-5 sample return mission, using a range of techniques.
There are impact events that changed our world.
The study suggests that there could have been more than one impact event on Earth.
The age-frequency distributions of impacts on the Moon may provide valuable information about the impacts on the Earth or inner Solar System.
An asteroid or meteorite impact can generate a lot of heat. If silicate material is present on both Earth and the Moon, this heat can cause melting and reformation in the form of small glass beads.
Sometimes other materials on the Moon can get bound up in impact spherules and we can analyze them.
Scientists can study these spherules if they get their hands on some of them. The chance to do that was offered by the Chang'e-5 mission.
A team led by the Chinese Academy of Geological Sciences in Beijing isolated 215 spherical objects, ranging in size from 50 to 200 micrometers, from some of the soil Chang'e-5 collected and set about conducting their analysis.
There wasn't enough material to allow for a detailed study. Researchers used various tests to determine their age on the rest of the 135.
The technique is based on radioactive decay. An estimate of the sample's age can be given by the relative amounts of the two elements in the sample.
"We combined a wide range of analytical techniques, numerical modeling, and geological surveys to determine how these tiny glass beads from the moon were formed and when."
The spherules were mostly from the region around the Chang'e-5 landers. They could be thrown around 100 kilometers from the impact site.
The simulations show that the spherules formed in craters between 100 and 1,300 meters in size. The team was able to identify craters from the region in which they may have arisen.
The upper range of ages for the spherules was between a few million and 2 billion years old. The spherule was dated to 34 million years ago. There are a lot of craters from the late Eocene in the latter.
The origin point of these events could be a smash-up in the asteroid belt, which could have produced rocks that hit Earth and the Moon at the same time. This could help us understand how impactors form and evolve.
The next step would be to compare the data from the Chang'e-5 samples with other lunar soils and crater ages to see if there are any new impact events.
The research was published in a peer-reviewed journal.
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