An international team of researchers studying dust samples retrieved by the Hayabusa2 space probe found some of its dust grains are older than the solar system.in their published paper astrophysical journal lettersthe team described their analysis of asteroid dust and their findings.
The Hayabusa2 space probe began its mission in 2014, when it launched into space aboard the H-IIA 202 rocket. Four years later, it rendezvoused with the near-Earth asteroid 162173 Ryugu. After orbiting the asteroid for two years, it landed on its surface and took samples of its surface dust. Then it exploded and returned to Earth.
Ryukyu is 300 million kilometers from Earth and orbits the sun every 16 months. It is described as just a collection of gravel, possibly made from fragments of several other asteroids. Other studies have suggested that it likely formed in the outer solar system and has been wriggling inward ever since—others think its dust hints that Earth’s water may have come from a similar asteroid.
Since the dust samples collected by the probes have returned to Earth, some of them have been passed on to different researchers around the world, eager to test them in different ways. In the new study, the researchers tried to determine its age — they noticed that the different kinds of grains in asteroids like Ryugu came from different types of stars and stellar processes. The age of grains in dust can be identified and determined by their isotopic signature.
When studying the Ryugu dust samples, the researchers compared them to grains found in carbonaceous chondrites found on Earth. They point out that only 5 percent of such meteorites have been found to contain grains that predate the formation of the solar system — some of which date back 7 billion years. The researchers found that the grains in the dust sample were the same as all other grains seen in meteorites, suggesting that it also predates the solar system. In particular, they noted, a silicate known to be easily destroyed must have been protected in some way from the sun.
Space mission suggests Earth’s water may come from asteroids: study
Jens Barosch et al., Pre-Solar Stardust in Asteroid Ryugu, astrophysical journal letters (2022). DOI: 10.3847/2041-8213/ac83bd
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Citation: Dust grains from asteroid Ryugu older than our solar system (18 Aug 2022) Retrieved 18 Aug 2022 from https://phys.org/news/2022-08-grains-asteroid-ryugu- older-solar.html retrieved
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