Unveiling the space-weathered features of asteroid Ryugu

Unveiling the space-weathered features of asteroid Ryugu
by Riko Seibo
Tokyo, Japan (SPX) Apr 30, 2024

New insights into the magnetic and physical environment of interplanetary space have been revealed through the analysis of asteroid Ryugu samples, retrieved by the Hayabusa2 spacecraft of the Japanese Space Agency. The research led by Professor Yuki Kimura of Hokkaido University, along with colleagues from 13 other Japanese institutions, is detailed in the journal Nature Communications.

The team utilized electron holography, a technique involving electron waves to penetrate the samples, exposing their structural, magnetic, and electrical properties. The Hayabusa2 mission, which arrived at Ryugu on June 27, 2018, executed two sample collection maneuvers before returning them to Earth in December 2020. It continues its exploration, targeting additional asteroid observations in 2029 and 2031.

Direct sample collection enables the study of space-weathering effects-alterations from solar wind and micrometeoroid impacts-unobtainable from meteorites that naturally land on Earth. These terrestrial samples often originate from deeper within an asteroid and undergo alteration during atmospheric entry.

"The signatures of space weathering we have detected directly will give us a better understanding of some of the phenomena occurring in the Solar System," says Kimura. He explains that the strength of the magnetic field in the early solar system decreased as planets formed, and measuring the remnant magnetization on asteroids can reveal information about the magnetic field in the very early stages of the solar system.

Kimura highlighted, "Future studies will allow us to date surfaces on airless bodies and refine data interpretation from remote sensing technologies."

A key discovery was the alteration of magnetite-based framboids, which lost their magnetic properties due to high-velocity micrometeoroid impacts. These framboids are surrounded by iron nanoparticles, potentially offering future insights into the asteroid's magnetic history.

"Although our study is primarily for fundamental scientific interest and understanding, it could also help estimate the degree of degradation likely to be caused by space dust impacting robotic or manned spacecraft at high velocity," Kimura concludes.

Research Report:Nonmagnetic framboid and associated iron nanoparticles with a space-weathered feature from asteroid Ryugu