Koji Matsumoto
A5089906631- Planetary Science and Exploration
- Astro and Planetary Science
- Geophysics and Gravity Measurements
- GNSS positioning and interference
- Solar and Space Plasma Dynamics
- Space Exploration and Technology
- Isotope Analysis in Ecology
- Dark Matter and Cosmic Phenomena
- Ionosphere and magnetosphere dynamics
- Inertial Sensor and Navigation
- Space Science and Extraterrestrial Life
- Geomagnetism and Paleomagnetism Studies
- Spacecraft and Cryogenic Technologies
- Magneto-Optical Properties and Applications
- Gout, Hyperuricemia, Uric Acid
- Space Satellite Systems and Control
- Astrophysics and Cosmic Phenomena
- Geology and Paleoclimatology Research
- Spacecraft Design and Technology
- Particle physics theoretical and experimental studies
- Oceanographic and Atmospheric Processes
- Astronomical Observations and Instrumentation
- Radio Astronomy Observations and Technology
- Spacecraft Dynamics and Control
- Geological and Geochemical Analysis
National Astronomical Observatory of Japan
2015-2025
The Graduate University for Advanced Studies, SOKENDAI
2015-2023
Tohoku University
2007-2023
Japan Aerospace Exploration Agency
2009-2023
Hiroshima University of Economics
2013-2023
Hitachi Global Storage Technologies (United States)
2023
Institute of Space and Astronautical Science
2009-2022
Chiba Institute of Technology
2022
Subaru (Japan)
2021
Japan Spaceguard Association
2021
Results from 1036 days of solar neutrino data accumulated in the upgraded Kamiokande detector (Kamiokande III) are presented. The $^{8}\mathrm{B}$ flux observed III is ${2.82}_{\ensuremath{-}0.24}^{+0.25}$ (stat) \ifmmode\pm\else\textpm\fi{} 0.27 (syst) \ifmmode\times\else\texttimes\fi{} ${10}^{6}$ ${\mathrm{cm}}^{\ensuremath{-}2}$${\mathrm{s}}^{\ensuremath{-}1}$; combined II and (2079 total) 2.80 0.19 0.33 ${\mathrm{cm}}^{\ensuremath{-}2}$${\mathrm{s}}^{\ensuremath{-}1}$, which 49% to 64%...
The Hayabusa2 spacecraft arrived at the near-Earth carbonaceous asteroid 162173 Ryugu in 2018. We present observations of Ryugu's shape, mass, and geomorphology. has an oblate "spinning top" with a prominent circular equatorial ridge. Its bulk density, 1.19 ± 0.02 grams per cubic centimeter, indicates high-porosity (>50%) interior. Large surface boulders suggest rubble-pile structure. Surface slope analysis shows shape may have been produced from having once spun twice current rate. Coupled...
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...
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...
Abstract C-type asteroids 1 are considered to be primitive small Solar System bodies enriched in water and organics, providing clues the origin evolution of building blocks life. asteroid 162173 Ryugu has been characterized by remote sensing 2–7 on-asteroid measurements 8,9 with Hayabusa2 (ref. 10 ). However, ground truth provided laboratory analysis returned samples is invaluable determine fine properties other planetary bodies. We report preliminary results analyses on from particle size...
Carbonaceous meteorites are thought to be fragments of C-type (carbonaceous) asteroids. Samples the asteroid (162173) Ryugu were retrieved by Hayabusa2 spacecraft. We measured mineralogy and bulk chemical isotopic compositions samples. The samples mainly composed materials similar those carbonaceous chondrite meteorites, particularly CI (Ivuna-type) group. consist predominantly minerals formed in aqueous fluid on a parent planetesimal. primary altered fluids at temperature 37° ± 10°C, about...
Collecting a sample of asteroid Ryugu The Hayabusa2 spacecraft recently traveled to the nearby carbonaceous collect samples and return them Earth for laboratory analysis. Morota et al. describe Hayabusa2's first collection, taken during brief touchdown on Ryugu's surface. Close-up images video sampling process allowed authors investigate surface colors morphology small scale. Relating these craters stratigraphy constrains evolution Ryugu. conclude that experienced prior period strong solar...
The Hayabusa2 spacecraft collected samples from the surface of carbonaceous near-Earth asteroid (162173) Ryugu and brought them to Earth. were expected contain organic molecules, which record processes that occurred in early Solar System. We analyzed molecules extracted samples. identified a variety containing atoms CHNOS, formed by methylation, hydration, hydroxylation, sulfurization reactions. Amino acids, aliphatic amines, carboxylic polycyclic aromatic hydrocarbons, nitrogen-heterocyclic...
Presented here are the observations and interpretations from a comprehensive analysis of 16 representative particles returned C-type asteroid Ryugu by Hayabusa2 mission. On average consist 50% phyllosilicate matrix, 41% porosity 9% minor phases, including organic matter. The abundances 70 elements in close agreement with those CI chondrites. Bulk show higher δ18O, Δ17O, ε54Cr values than As such, sampled most primitive least-thermally processed protosolar nebula reservoirs. Such finding is...
The Hayabusa2 spacecraft investigated the C-type (carbonaceous) asteroid (162173) Ryugu. mission performed two landing operations to collect samples of surface and subsurface material, latter exposed by an artificial impact. We present images second touchdown site, finding that ejecta from impact crater was at sample location. Surface pebbles both sites show morphological variations ranging rugged smooth, similar Ryugu's boulders, shapes quasi-spherical flattened. were returned Earth on 6...
Abstract Volatile and organic-rich C-type asteroids may have been one of the main sources Earth’s water. Our best insight into their chemistry is currently provided by carbonaceous chondritic meteorites, but meteorite record biased: only strongest types survive atmospheric entry are then modified interaction with terrestrial environment. Here we present results a detailed bulk microanalytical study pristine Ryugu particles, brought to Earth Hayabusa2 spacecraft. particles display close...
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 Martian moons exploration, MMX, is the new sample return mission planned by Japan Aerospace Exploration Agency (JAXA) targeting two with scheduled launch in 2024 and to Earth 2029. The major scientific objectives of this are determine origin Phobos Deimos, elucidate early Solar System evolution terms volatile delivery across snow line terrestrial planets having habitable surface environments, explore evolutionary processes both Mars environment. To achieve these objectives, during a...
Oceanic tidal loading signals are in general smaller than solid Earth tide signals, but they can be measured by geodetic technique and need to accurately corrected for because a source of noise. In order meet this requirement we have developed program compute the most Japanese region using combination global regional ocean models fine-scale land-sea grids. The computes six kinds (radial horizontal displacements, gravity, tilt, strain, deflection vertical) 21 constituents including long-period tide.
The farside gravity field of the Moon is improved from tracking data Selenological and Engineering Explorer (SELENE) via a relay subsatellite. new model reveals that has negative anomaly rings unlike positive anomalies on nearside. Several basins have large central highs, likely due to super-isostatic, dynamic uplift mantle. Other with highs are associated mare fill, implying basalt eruption facilitated by developed faults. Basin topography mantle supported rigid lithosphere, whereas...
4-[5-(Pyridin-4-yl)-1<i>H</i>-1,2,4-triazol-3-yl]pyridine-2-carbonitrile (FYX-051) is a potent inhibitor of bovine milk xanthine oxidoreductase (XOR). Steady-state kinetics study showed that it initially behaved as competitive-type with <i>K</i><sub>i</sub> value 5.7 × 10<sup>−9</sup> M, then after few minutes formed tight complex XOR via Mo-oxygen-carbon atom covalent linkage, reported previously (<i>Proc Natl Acad Sci USA</i><b>101:</b>7931–7936, 2004). Thus, FYX-051 hybrid-type exhibiting...
Abstract The internal structure of the Moon is important for discussions on its origin and evolution. However, deep still debated due to absence comprehensive seismic data. This study explores lunar interior models by complementing Apollo travel time data with selenodetic which have recently been improved Gravity Recovery Interior Laboratory (GRAIL) Lunar Laser Ranging (LLR). observed can be explained including a deep‐seated zone low velocity ( S wave = 2.9 ± 0.5 km/s) viscosity (∼3 × 10 16...
Without a protective atmosphere, space-exposed surfaces of airless Solar System bodies gradually experience an alteration in composition, structure and optical properties through collective process called space weathering. The return samples from near-Earth asteroid (162173) Ryugu by Hayabusa2 provides the first opportunity for laboratory study space-weathering signatures on most abundant type inner solar system body: C-type asteroid, composed materials largely unchanged since formation...
The near-Earth carbonaceous asteroid (162173) Ryugu is expected to contain volatile chemical species that could provide information on the origin of Earth's volatiles. Samples were retrieved by Hayabusa2 spacecraft. We measured noble gas and nitrogen isotopes in samples found they are dominated presolar primordial components, incorporated during Solar System formation. Noble concentrations higher than those Ivuna-type (CI) chondrite meteorites. Several host phases isotopically distinct have...