Meteor showers from space may not have fallen on our planet over the past 500 million years the way we thought, according to a new analysis.
After analyzing 8,484 kilograms of sedimentary rock from the ancient seabed, scientists found that major collisions in the asteroid belt did not make any significant contribution to the number of meteorite impacts on Earth, as had been assumed. Scientists say this is a discovery that could help protect Earth from asteroid impacts in the future.
Geologist Berger Schmitz, from Lund University in Sweden, said: “The research community previously believed that the meteor flow to Earth was linked to dramatic events in the asteroid belt. The new study, however, shows that the flow was very stable.”
Tracing the history of Earth’s meteorite is not easy. Impact events involving large objects rarely leave a wide crater; Many space rocks disintegrate upon entering the atmosphere, leaving only debris to fall to Earth.
From the bottoms of the ancient seas in China, Russia and Sweden, they extracted thousands of kilograms of limestone, representing 15 different periods of time in the eons of life.
These bits of limestone were then dissolved in acid, a technique that allows the extraction of chromium spinel — tiny bits of chromium oxide, a decay-resistant mineral found in meteorites.
“In all, we extracted chromium oxide from nearly 10,000 different meteorites,” Schmitz said. Then chemical analyzes enabled us to identify the types of meteorites.
Astonishingly, their results show a stable flow, composed mostly of cartilaginous (rocky, non-metallic) meteorites, similar to the current flow. The stark exception is the increase in this type of meteorite 466 million years ago, linked to the disintegration of the parent body L-chondrite, a type of meteorite conspicuously low in iron.
During this time, the meteorite flux increased by a factor of 300, and even today, approximately one-third of all meteorites that fall to Earth are from this parent body.
“We were very surprised to learn that only one of the 70 largest asteroid collisions in the past 500 million years has led to an increased flow of meteorites to Earth,” Schmitz said.
There is a time period of 190 million years from the Carboniferous to the early Jurassic without the chromium-spinel data, and we know that there was an asteroid disintegration affecting Earth during that time.
“The future impact of even a small asteroid for example in the sea near a populated area could lead to catastrophic results,” Schmitz said. “This study provides an important understanding that we can use to prevent this from happening; for example, by trying to influence the trajectory of approaching celestial bodies. Quickly”.
And publish the research in PNAS.
Source: Science Alert