M. Komatsu
A5052150572- Astro and Planetary Science
- Planetary Science and Exploration
- High-pressure geophysics and materials
- Isotope Analysis in Ecology
- Geological and Geochemical Analysis
- Nuclear Physics and Applications
- earthquake and tectonic studies
- Spacecraft and Cryogenic Technologies
- Copper Interconnects and Reliability
- Astrophysics and Star Formation Studies
- X-ray Diffraction in Crystallography
- Metal and Thin Film Mechanics
- Stellar, planetary, and galactic studies
- Semiconductor materials and devices
- Geomagnetism and Paleomagnetism Studies
- Paleontology and Stratigraphy of Fossils
- Hydrocarbon exploration and reservoir analysis
- Microstructure and mechanical properties
- nanoparticles nucleation surface interactions
- Crystallization and Solubility Studies
- Semiconductor materials and interfaces
- Electronic Packaging and Soldering Technologies
- Grouting, Rheology, and Soil Mechanics
- Advanced ceramic materials synthesis
- CO2 Sequestration and Geologic Interactions
Waseda University
2012-2024
The Graduate University for Advanced Studies, SOKENDAI
2015-2024
Saitama Prefectural University
2022-2024
Nippon Soken (Japan)
2017-2020
Okayama University
2019-2020
University of South Florida
2020
Japan Synchrotron Radiation Research Institute
2016
Ehime University
1989-2014
National Institute for Materials Science
2008-2011
The University of Tokyo
2001-2009
The asteroid impact near the Russian city of Chelyabinsk on 15 February 2013 was largest airburst Earth since 1908 Tunguska event, causing a natural disaster in an area with population exceeding one million. Because it occurred era modern consumer electronics, field sensors, and laboratory techniques, unprecedented measurements were made event meteoroid that caused it. Here, we document account what happened, as understood now, using comprehensive data obtained from astronomy, planetary...
Hayabusa2 at the asteroid Ryugu Asteroids fall to Earth in form of meteorites, but these provide little information about their origins. The Japanese mission is designed collect samples directly from surface an and return them for laboratory analysis. Three papers this issue describe team's study near-Earth carbonaceous 162173 Ryugu, which spacecraft arrived June 2018 (see Perspective by Wurm). Watanabe et al. measured asteroid's mass, shape, density, showing that it a “rubble pile” loose...
Samples of the carbonaceous asteroid (162173) Ryugu were collected and brought to Earth by Hayabusa2 spacecraft. We investigated macromolecular organic matter in samples found that it contains aromatic aliphatic carbon, ketone, carboxyl functional groups. The spectroscopic features are consistent with those chemically primitive chondrite meteorites experienced parent-body aqueous alteration (reactions liquid water). morphology carbon includes nanoglobules diffuse associated phyllosilicate...
Abstract Meteoritical Bulletin 110 contains the 2802 meteorites approved by Nomenclature Committee of Society in 2021. It includes 10 falls (Arpu Kuilpu, Djadjarm, Glendale, Kindberg, Madura Cave, Motopi Pan, Orconuma, Punggur, Tihigrin, Winchcombe), with 2014 ordinary chondrites (including 1 ungrouped chondrite), 220 carbonaceous 11 ungrouped), 212 HED achondrites, 69 lunar meteorites, 62 ureilites, 43 iron 35 Martian 31 Rumuruti chondrites, 27 primitive 24 mesosiderites, 19 relict (all...
Abstract Meteoritical Bulletin 111 contains the 3094 meteorites approved by Nomenclature Committee of Society in 2022. It includes 11 falls (Antonin, Botohilitano, Cranfield, Golden, Great Salt Lake, Longde, Msied, Ponggo, Qiquanhu, Tiglit, Traspena), with 2533 ordinary chondrites, 165 HED, 123 carbonaceous chondrites (including 4 ungrouped), 82 lunar meteorites, 28 Rumuruti 27 iron 23 ureilites, 22 mesosiderites, Martian 21 primitive achondrites (one 17 ungrouped achondrites, 13 pallasites,...
Context. The current period is conducive to exploring our Solar System's origins with recent and future space sample return missions, which provide invaluable information from known System asteroids comets Hayabusa2 mission of the Japan Aerospace Exploration Agency (JAXA) recently brought back samples surface Ryugu carbonaceous asteroid. Aims. We aim identify different forms chemical composition organic matter minerals that constitute these primitive objects, shed light on origins. Methods....
Abstract Transmission electron microscopy analyses of Hayabusa2 samples show that Ryugu organic matter exhibits a range morphologies, elemental compositions, and carbon functional chemistries consistent with those carbonaceous chondrites have experienced low‐temperature aqueous alteration. Both nanoglobules diffuse are abundant. Non‐globular particles also present, including some contain nanodiamond clusters. Diffuse is finely distributed in around phyllosilicates, forms coatings on other...
Abstract A double-source evaporator which can be set in the specimen chamber of a high voltage electron microscope has been constructed, With use evaporator, isolated gold clusters 5 ~ 10 nm size were first prepared on supporting film amorphous carbon, and then copper atoms deposited onto (and course as well), was kept at room temperature. Upon deposition copper, changed into highly concentrated, homogeneously mixed Au—Cu alloy clusters. The atom diffusivity deduced from present observations...
Abstract Based upon our characterization of three separate stones by electron and X‐ray beam analyses, computed microtomography, Raman microspectrometry, visible‐ IR spectrometry, Sutter's Mill is a unique regolith breccia consisting mainly various CM lithologies. Most samples resemble existing available 2 chondrites, chondrules calcium‐aluminum‐rich inclusion (CAI) set within phyllosilicate‐dominated matrix (mainly serpentine), pyrrhotite, pentlandite, tochilinite, variable amounts Ca‐Mg‐Fe...
Significance The oldest solar system solids dated are refractory inclusions [Ca-Al–rich (CAIs) and amoeboid olivine aggregates (AOAs)], which occur in chondritic meteorites provide records of high-temperature processes the early system. An ultrarefractory CAI silica-phase quartz an AOA from carbonaceous chondrite Yamato-793261, indicating formation over a temperature range exceeding 650 K. minerals have 16 O-rich compositions consistent with nebular setting associated inclusions. This...
Abstract Meteoritical Bulletin 109 contains the 2790 meteorites approved by Nomenclature Committee of Society in 2020. It includes 17 falls (Al Farciya, Auckland, Cavezzo, Flensburg, Gatuto, Kolang, Mahadeva, Matarka, Narashino, Novo Mesto, Oslo, Saint‐Ouen‐en‐Champagne, Santa Filomena, Tarda, Tiros, Wad Lahteyba, Zhob), with 2336 ordinary chondrites, 131 carbonaceous chondrites (including 8 ungrouped ones), 123 HED achondrites, 41 Martian meteorites, 35 lunar 23 iron 21 ureilites, primitive...
Abstract We have conducted a NanoSIMS-based search for presolar material in samples recently returned from C-type asteroid Ryugu as part of JAXA's Hayabusa2 mission. report the detection all major grain types with O- and C-anomalous isotopic compositions typically identified carbonaceous chondrite meteorites: 1 silicate, oxide, O-anomalous supernova ambiguous phase, 38 SiC, 16 grains. At least two grains are graphites, whereas several moderate C anomalies probably organics. The silicate was...
Abstract— Amoeboid olivine aggregates (AOAs) from the reduced CV chondrites Efremovka, Leoville and Vigarano are irregularly‐shaped objects, up to 5 mm in size, composed of forsteritic (Fa <10 ) a refractory, Ca, Al‐rich component. The AOAs depleted moderately volatile elements (Mn, Cr, Na, K), Fe, Ni‐metal sulfides contain no low‐Ca pyroxene. refractory component consists fine‐grained calcium‐aluminum‐rich inclusions (CAIs) Al‐diopside, anorthite (An 100 ), magnesium‐rich spinel (∼1 wt%...
The Main Zone of the Hidaka Metamorphic Belt is an uplifted crustal section island‐arc type. crust was formed during early Tertiary time, as a result collision between two arc–trench systems Cretaceous age. metamorphic sequence divided into four zones (I–IV), in which zone IV granulite facies. A detailed study evolution Belt, based on revised P–T–t analysis rocks, notably newly found staurolite‐bearing granulite, confirms prograde isobaric heating path, after supposed event tectonic...
Dmitryivanovite (CaAl2O4) is a newly described, calcium aluminum oxide from the Northwest Africa 470 (NWA470) CH3 chondrite (Ivanova et al. 2002). NWA470 contains abundant small Ca,Alrich inclusions (CAIs), and dmitryivanovite, whose composition close to stoichiometric CaAl2O4 [Ca1.000(Al1.993Si0.003Ti0.002)1.998O4], was found in one of these CAIs. It occurs as ~10 μm subhedral grains intergrown with grossite (CaAl4O7), perovskite, melilite. Electron backscatter diffraction (EBSD) analysis...
In July 2018, heavy rain and a large amount of damage to geo-structures natural slopes were reported in Okayama, Japan. particular, the area surrounding Oda River System, 52 people drowned due breach river banks. Besides flooding rivers, earth-fill dams many water reservoirs damaged. The stability number Setouchi is very important. Heavy often associated with collapse slopes. shallow slope failures or debris flows occurred over wide area, particularly western part prefecture. Through...