Ancient dust particles older than the solar system itself have been found in samples from the asteroid Ryugu brought back to Earth by the Japanese spacecraft Hayabusa-2 nearly two years ago.
The presence of this pre-solar material in Ryugu is not surprising, as similar ancient grains have previously been found in several carbonaceous chondrite meteorites, which are carbon-rich chunks of space rock that survived a fall through Earth’s atmosphere and landed on the planet.
The ancient particles in the Ryugu samples are made of silicon carbide, a chemical compound not found naturally on Earth. There are different kinds of silicon carbide grains that differ in what scientists call their isotopic signatures, or the number of neutrons in the core of the silicon and carbon atoms that make up the compound, according to the researchers behind the new study.
Related: Asteroid Ryugu contains material older than planets, one of the most primitive ever studied on Earth
In the Ryugu samples, the researchers found previously known types of silicon carbide, as well as an extremely rare form of silicate that is easily destroyed by chemical processes occurring on asteroids. The material was found “in a less chemically altered fragment that likely protected it from such activity,” the researchers said in a statement. (will open in a new tab).
The study (will open in a new tab) was published in the Astrophysical Journal Letters on Monday (August 15).
Japan’s Hayabusa 2 mission landed on Ryugu, a near-Earth asteroid that orbits the Sun once every 16 months, in July 2019. The probe has delivered about one fifth of an ounce (5 grams) of space dust to Earth, which has been analyzed in labs around the world since it was delivered to Earth in December 2020.
In fact, a separate study (will open in a new tab) published Tuesday (August 16) in the journal Nature Astronomy also analyzes material from Ryugu. The scientists behind this study used a different type of isotopic analysis, as well as a technique called scanning transmission X-ray microscopy, among other studies.
This study found compounds that cannot withstand temperatures above 86 degrees Fahrenheit (30 degrees Celsius), which, combined with other findings, suggests that Ryugu formed in the outer solar system and migrated inward, according to the statement. (will open in a new tab) from the Japan Aerospace Exploration Agency, which manages the Hayabusa2 mission.
Both studies are examples of the work involved in bringing asteroid samples back to Earth for analysis using ground equipment.
“Being able to identify and study these grains in the lab could help us understand the astrophysical phenomena that have shaped our solar system, as well as other space objects,” said Larry Nittler, a planetary scientist at Arizona State University and co-author of the study. silicon carbide, the statement said.
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