“The signatures of space erosion that we detect directly will allow us to better understand some of the events occurring in the solar system.”

Samples collected from asteroid Ryugu appear to hold secrets about the Solar System’s past; the bombardment that asteroids currently undergo as they drift between planets, and perhaps even plans for future asteroid mining missions.

As asteroids explore interplanetary space, they are exposed to high-energy particles thrown from the Sun by the solar wind, as well as small objects called micrometeoroids. These interplanetary environmental factors can cause “space erosion” but are difficult to see from a distance. In fact, meteors breaking off from asteroids are subjected to intense heating as they pass through the Earth’s atmosphere and reach the surface of our planet. This means that such changes are not seen in samples of asteroids that fell here.

However, the influence of interplanetary space is clearly visible in the samples collected directly from asteroids And that’s what humanity has been doing lately; for example, with NASA’s OSIRIS-REx mission and of course the Japanese Hayabusa2 spacecraft. The examples used by the team led by Yuki Kimura of Hokkaido University relate to the latter.

The Hayabusa2 mission rendezvoused with Ryugu three and a half years after its launch in June 2014. Haybusa2 spent a year on the asteroid, which is about 3,000 feet (900 meters) in diameter, before diving in and collecting a sample from its surface. June 2018. This Ryugu sample returned to Earth on December 6, 2020, when Haybusa2 left to explore other asteroids.

“The signatures of space erosion that we directly detected will allow us to better understand some of the events occurring in the solar system,” Kimura explained.

Planning space missions from Ryugu

One of the intriguing results that Kimura and his colleagues found in the Ryugu Hayabusa2 samples was the presence of tiny mineral grains called framboids. These framboids were composed of iron oxide but appear to have completely lost their normal magnetic properties. The team estimates that this occurred when Ryugu was bombarded by micrometeoroids no wider than 0.002 centimeters.