11:45 AM - 12:00 PM
[PPS07-11] Visualization of magnetic field and interior minerals of returned sample by Hayabusa2
Keywords:Aqueous alteration, Crystal growth, Electron microscope, Asteroid
The Hayabusa2 mission successfully collected samples from the asteroid Ryugu, providing a unique opportunity to investigate the mineralogical and magnetic properties of the primitive solar system. In this study, we focus on two magnetic field visualization techniques, electron holography and image displacement analysis electron microscopy (IDAEM), and demonstrate a comprehensive analysis of the internal mineral structure and internal and external magnetic field distribution of the Ryugu samples.
The nanoscale magnetic domain structure of magnetite (Fe3O4) and pyrrhotite (Fe1-xS) in the Ryugu sample, observed using electron holography, shows that framboidal magnetite has stable remanent magnetization, suggesting that it has the ability to record the magnetic field of its surrounding environment at the time of its formation. In contrast, pyrrhotite formed at the same time was observed to have no stable remanent magnetization due to the relatively shorter timescale in the magnetic domain relaxation process. Furthermore, we found evidence of the reduction of magnetite by a high-speed micro-dust collision, forming a non-magnetic framboid and metallic iron nanoparticles with vortex domain structures.
We used IDAEM to successfully visualize the external magnetic field of 10-30 micrometer blocks. Furthermore, we were able to relate the external magnetic field to the internal structure in three dimensions by cut and see metho using a focused ion beam-scanning electron microscope system. These results show that analyzing the nanoscale magnetic domain structure and internal minerals could provide new constraints on the mineralogical evolution of the asteroid Ryugu.
The authors thank the Ministry of Education, Culture, Sports, Science and Technology (MEXT) (grants JPMXS0450200421, JPMXS0450200521) and JSPS KAKENHI Grant Number JP23H03981 (Y.K.) for financial support and JEOL for providing access to the tabletop SEM (JCM-7000, NeoScope).
The nanoscale magnetic domain structure of magnetite (Fe3O4) and pyrrhotite (Fe1-xS) in the Ryugu sample, observed using electron holography, shows that framboidal magnetite has stable remanent magnetization, suggesting that it has the ability to record the magnetic field of its surrounding environment at the time of its formation. In contrast, pyrrhotite formed at the same time was observed to have no stable remanent magnetization due to the relatively shorter timescale in the magnetic domain relaxation process. Furthermore, we found evidence of the reduction of magnetite by a high-speed micro-dust collision, forming a non-magnetic framboid and metallic iron nanoparticles with vortex domain structures.
We used IDAEM to successfully visualize the external magnetic field of 10-30 micrometer blocks. Furthermore, we were able to relate the external magnetic field to the internal structure in three dimensions by cut and see metho using a focused ion beam-scanning electron microscope system. These results show that analyzing the nanoscale magnetic domain structure and internal minerals could provide new constraints on the mineralogical evolution of the asteroid Ryugu.
The authors thank the Ministry of Education, Culture, Sports, Science and Technology (MEXT) (grants JPMXS0450200421, JPMXS0450200521) and JSPS KAKENHI Grant Number JP23H03981 (Y.K.) for financial support and JEOL for providing access to the tabletop SEM (JCM-7000, NeoScope).