(ORDO NEWS) — Planetologists have found in rock samples from the asteroid Ryugu the first evidence that about 32-33% of the earth’s reserves of zinc and copper were delivered to the Earth‘s surface by carbonaceous chondrites, asteroids from the distant approaches of the solar system.
“The proportions of zinc and copper isotopes in rock samples from the asteroid Ryugu show that almost all of the reserves of these metals appeared on the Earth’s surface as a result of impacts of small celestial bodies.
Like Ryugu himself, a third of them were carbonaceous chondrites from the far edges of the solar system, and the rest 67% of the copper and zinc reserves were delivered to Earth by other types of chondrite asteroids,” the researchers write.
The first samples of rocks and soil from the asteroid Ryugu were delivered to Earth at the end of 2020 by the Japanese Hayabusa-2 probe. It was launched into space in early December 2014 to study, collect and return samples of the solar system’s primary matter.
He successfully completed this task in February 2019. In accordance with the intentions of the organizers of the mission, the study of the Ryugu rocks will bring humanity closer to understanding how our luminary, the Earth and all other worlds were formed.
A team of planetary scientists led by Seiichiro Watanabe, scientific director of the Hayabusa-2 mission, used these rock samples to unravel the history of the formation of terrestrial reserves of copper and zinc.
As scientists note, both of these metals are of interest to astronomers because their compounds easily escape into space during the formation of planets, so they can be used to study the history of the formation of the Earth and other worlds of the solar system.
Isotopic history of the formation of the Solar System
With similar ideas, the researchers measured the zinc and copper isotope fractions in four Hayabusa-2 rock samples, after which they compared these measurements with similar data for various terrestrial rocks, as well as for six meteorites that fell to Earth.
In the last few decades. Some of them, like the asteroid Ryugu, formed on the far approaches of the solar system, while others arose in its near regions.
The scientists found that all Ryugu rock samples contained relatively large amounts of heavy zinc-66 atoms, while the concentrations of heavy copper isotopes in them were close to those of terrestrial silicate rocks.
In general, samples from the asteroid turned out to be very close in this respect to the Ales meteorite, which belongs to a rare type of carbonaceous chordrites, unusually rich in water, organics and various volatile substances.
Using the results of these measurements, planetary scientists calculated the contribution made by Ryugu and similar asteroids from the outskirts of the solar system to the reserves of terrestrial rocks in general, as well as copper and zinc in particular.
According to Watanabe and his colleagues, these celestial bodies account for about 5-6% of the total mass of the Earth, as well as about 32-33% of the earth’s reserves of copper and zinc.
This suggests that small celestial bodies from the cold peripheral regions of the solar system played an important role in replenishing its reserves of volatile substances, including organic molecules and water, necessary for the origin of life.
This must be taken into account both when analyzing the ancient history of the Earth, and when searching for possible candidates for the role of its “twins” outside the solar system, the scientists concluded.
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