Samples retrieved from asteroid Ryugu by Hayabusa2 reveal evidence of changes experienced by the surface, including damage likely caused by micrometeoroid bombardment. Using electron holography to examine the samples’ structure and properties, researchers led by Professor Yuki Kimura at Hokkaido University uncovered new insights into the magnetic and physical bombardment environment of interplanetary space. This study, published in Nature Communications, sheds light on the effects of space weathering, which are difficult to study using meteorite samples that land on Earth naturally.
Hayabusa2 reached asteroid Ryugu in June 2018, collected samples during two touchdowns, and returned them to Earth in December 2020. The spacecraft is now on its way to observe two other asteroids in 2029 and 2031. Collecting samples directly from an asteroid allows researchers to examine long-term effects of exposure to the space environment, such as the solar wind and micrometeoroid impacts. By studying these changes, scientists can gain a better understanding of phenomena occurring in the Solar System and the magnetic field in the early stages of its formation.
The research team’s findings include the detection of space weathering signatures, providing insights into the magnetic field evolution on asteroids over time. One intriguing discovery was the complete loss of magnetic properties in small mineral grains known as framboids, composed of magnetite. The researchers attribute this loss to collisions with high-velocity micrometeoroids in the range of 2 to 20 micrometers in diameter. Surrounding the framboids were thousands of metallic iron nanoparticles, which hold the potential to reveal more about the asteroid’s magnetic history.
In addition to advancing fundamental scientific knowledge, this study could have practical implications for estimating the damage that space dust impacts may cause to robotic or manned spacecraft traveling at high velocities. Understanding the degradation caused by micrometeoroid impacts is crucial for spacecraft design and mission planning. The research also has implications for revealing the relative ages of surfaces on airless bodies and aiding in the interpretation of remote sensing data collected from these bodies. By studying the magnetic properties of asteroids, scientists can gain valuable insights into the history and dynamics of the Solar System.
Overall, the analysis of samples from asteroid Ryugu provides valuable information about the effects of space weathering and micrometeoroid impacts on asteroid surfaces. By using advanced techniques such as electron holography, researchers are able to uncover new details about the magnetic and physical environment of interplanetary space. This study not only contributes to our understanding of the Solar System’s evolution but also has practical applications for spacecraft design and mission planning. As Hayabusa2 continues its journey through space, it will likely yield more valuable insights into the history and composition of asteroids, further expanding our knowledge of the cosmos.
