Asteroid Ryugu contains dust older than the solar system

Ancient dust grains older than the solar system itself were found in samples from the asteroid Ryugu brought to Earth by the Japanese spacecraft Hayabusa2 nearly two years ago.

The presence of this pre-solar material in Ryugu is not a surprise, because similar ancient grains have already been found in several carbonaceous chondrite meteorites, which are pieces of carbon-rich space rock that survived the fall earth’s atmosphere land on the planet.

The ancient particles in the Ryugu samples are made of silicon carbide, a chemical compound that does not occur naturally on Earth. According to the researchers behind the new study, there are different types of silicon carbide grains that differ in what scientists call their isotopic signatures, or the number of neutrons at the core of the silicon and carbon atoms that make up the compound.

Related: Asteroid Ryugu contains materials older than planets, some of the most primitive ever studied on Earth

In the Ryugu samples, the researchers detected the previously known types of silicon carbide, but also an extremely rare form of silicate that is easily destroyed by chemical processes that take place in asteroids. The material was found “in a less chemically altered fragment that likely protected it from such activity,” the researchers said in a statement. statement (opens in a new tab).

The study (opens in a new tab) was published in the journal Astrophysical Journal Letters on Monday August 15.

the Japaneses Hayabusa2 mission landed on Ryugu, a near-Earth asteroid that orbits the sun every 16 months, in July 2019. The probe brought back to Earth about a fifth of an ounce (5 grams) of space dust, which has been analyzed in laboratories around the world since its delivery to Earth in December 2020.

In fact, separate research (opens in a new tab) published Tuesday, August 16 in the journal Nature Astronomy also analyzes Ryugu’s material. The scientists behind this research used a different type of isotopic analysis, as well as a technique called scanning transmission X-ray microscopy, among other studies.

This research 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 , according to a statement (opens in a new tab) of the Japan Aerospace Exploration Agency, which manages the Hayabusa2 mission.

Both studies are examples of work that relies on returning asteroid samples to Earth for analysis with terrestrial equipment.

“The ability to identify and study these grains in the lab can help us understand the astrophysical phenomena that have shaped our solar system, as well as other cosmic objects,” said Arizona State University planetary scientist Larry Nittler. and co-author of the silicon carbide study, said in the release.

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