In samples from the asteroid Ryugu that the Japanese Hayabusa2 spacecraft brought to Earth nearly two years ago, ancient bits of dust older than the solar system itself were discovered.
This pre-solar material was discovered in Ryugu, which is not surprising given that it was discovered in a number of carbonaceous chondrite meteorites, which are carbon-rich chunks of space rock that made it through Earth's atmosphere to land on the planet.
Samples from Ryugu contain ancient particles made of silicon carbide, a substance that doesn't exist naturally on Earth. The authors of the new study claim that there are many types of silicon carbide grains that vary according to what is known as their isotopic signatures or the number of neutrons in the cores of the silicon and carbon atoms that make up the combination.
Researchers found the previously recognized varieties of silicon carbide in the Ryugu samples, as well as a very uncommon silicate that is easily destroyed by the chemical processes that occur in asteroids. According to the researchers, the material was discovered "in a less-chemically-altered fragment that likely shielded it from such activity."
In July 2019, the Japanese Hayabusa2 mission made a landing on Ryugu, a near-Earth asteroid that makes one round of the sun every 16 months. Since the probe's arrival on Earth in December 2020, around one-fifth of an ounce (5 grams) of space dust has been brought back for analysis in laboratories all across the world.
In fact, additional research that was conducted separately and published on Tuesday, August 16 in the journal Nature Astronomy, also examines data from Ryugu. A new kind of isotopic analysis was employed in that study, along with additional investigations using a method called scanning transmission X-ray microscopy.
According to a statement from the Japan Aerospace Exploration Agency, which oversees the Hayabusa2 mission, that research discovered compounds that can't withstand temperatures above 86 degrees Fahrenheit (30 degrees Celsius), which when combined with other findings suggests that Ryugu formed in the outer solar system and migrated in.
Both investigations are illustrations of work that depends on returning asteroids' samples to Earth for equipment-based analysis.
In a statement, Larry Nittler, a planetary scientist at Arizona State University and a co-author of the silicon carbide study, said, "The opportunity to identify and study these grains in the lab can help us understand the astrophysical phenomena that shaped our solar system, as well as other cosmic objects."
