An extensive analysis of samples retrieved from asteroid Ryugu by Japan’s Hayabusa2 spacecraft has yielded fresh perspectives on the magnetic and physical effects within the interplanetary space environment. The findings, led by Professor Yuki Kimura from Hokkaido University and a team spanning 13 other institutions in Japan, have been detailed in the journal Nature Communications.
The investigation employed electron holography, a technique utilizing electron waves penetrating the samples, to unveil their structural intricacies and magnetic-electric properties. Hayabusa2 successfully reached asteroid Ryugu in June 2018, executing two meticulous touchdowns to collect samples before returning them to Earth in December 2020. Presently, the spacecraft continues its trajectory through space, with plans to observe two additional asteroids in 2029 and 2031.
A significant advantage of directly gathering samples from an asteroid lies in the opportunity to scrutinize the long-term consequences of exposure to the space environment. The constant bombardment by the “solar wind” and micrometeoroids induces changes known as space-weathering, a phenomenon challenging to study precisely using meteorite samples that land naturally on Earth, given their origin from the asteroid’s internal regions and the atmospheric descent effects.
One notable discovery unveiled by the study was the alteration of small mineral grains known as framboids, composed of magnetite, an iron oxide variant, which lost their typical magnetic properties entirely. This transformation is attributed to collisions with high-velocity micrometeoroids measuring between 2 and 20 micrometers in diameter. Surrounding the framboids were numerous metallic iron nanoparticles, offering potential insights into the asteroid’s magnetic field dynamics over extensive periods.
Professor Kimura emphasizes the significance of these findings in enhancing our understanding of solar system phenomena, particularly in elucidating the early solar system’s magnetic field evolution as planets formed. Moreover, the study’s outcomes hold promise in aiding the determination of surface relative ages on airless bodies and facilitating the accurate interpretation of remote sensing data from these celestial bodies.
While primarily driven by scientific curiosity, the study’s implications extend to practical considerations, such as assessing the potential degradation caused by space dust impacting spacecraft at high velocities, whether robotic or manned. Through continued exploration and analysis, researchers anticipate further revelations about the complex interactions shaping our cosmic neighborhood.
