Ryuji Okazaki
A5010219040- Astro and Planetary Science
- Planetary Science and Exploration
- Isotope Analysis in Ecology
- Geological and Geochemical Analysis
- High-pressure geophysics and materials
- Geology and Paleoclimatology Research
- Nuclear Physics and Applications
- Spacecraft and Cryogenic Technologies
- Space Exploration and Technology
- Mass Spectrometry Techniques and Applications
- Geomagnetism and Paleomagnetism Studies
- Methane Hydrates and Related Phenomena
- Laser-induced spectroscopy and plasma
- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Space Science and Extraterrestrial Life
- earthquake and tectonic studies
- Astronomical and nuclear sciences
- Polar Research and Ecology
- Geochemistry and Geologic Mapping
- Atmospheric and Environmental Gas Dynamics
- Solar and Space Plasma Dynamics
- Astrophysics and Cosmic Phenomena
- Radioactive contamination and transfer
- Neutrino Physics Research
Kyushu University
2013-2024
Keio University
2024
Kyushu Institute of Information Sciences
2022
Rigaku (Japan)
2021
The University of Tokyo
2001-2012
Tokyo University of Science
2003-2012
Kirinyaga University
2005
Earthquake Engineering Research Institute
2003-2004
The Hayabusa spacecraft successfully recovered dust particles from the surface of near-Earth asteroid 25143 Itokawa. Synchrotron-radiation x-ray diffraction and transmission scanning electron microscope analyses indicate that mineralogy mineral chemistry Itokawa are identical to those thermally metamorphosed LL chondrites, consistent with spectroscopic observations made Earth by spacecraft. Our results directly demonstrate ordinary most abundant meteorites found on Earth, come S-type...
Laboratory analysis of samples returned from an asteroid establishes a direct link between asteroids and meteorites provides clues to the complex history its surface.
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...
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...
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...
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...
The pristine sample from the near-Earth carbonaceous asteroid (162173) Ryugu collected by Hayabusa2 spacecraft enabled us to analyze extraterrestrial material without uncontrolled exposure Earth's atmosphere and biosphere. initial analysis team for soluble organic matter reported detection of wide variety molecules including racemic amino acids in samples. Here we report uracil, one four nucleobases ribonucleic acid, aqueous extracts In addition, nicotinic acid (niacin, a B3 vitamer), its...
Doppler weather radar imaging enabled the rapid recovery of Sutter's Mill meteorite after a rare 4-kiloton TNT-equivalent asteroid impact over foothills Sierra Nevada in northern California. The recovered meteorites survived record high-speed entry 28.6 kilometers per second from an orbit close to that Jupiter-family comets (Tisserand's parameter = 2.8 ± 0.3). is regolith breccia composed CM (Mighei)-type carbonaceous chondrite and highly reduced xenolithic materials. It exhibits...
Meteorite studies suggest that each solar system object has a unique oxygen isotopic composition. Chondrites, the most primitive of meteorites, have been believed to be derived from asteroids, but compositions asteroids themselves not established. We measured, using secondary ion mass spectrometry, rock particles asteroid 25143 Itokawa returned by Hayabusa spacecraft. Compositions are depleted in (16)O relative terrestrial materials and indicate Itokawa, an S-type asteroid, is one sources LL...
Abstract On the basis of observations using Cs‐corrected STEM , we identified three types surface modification probably formed by space weathering on surfaces Itokawa particles. They are (1) redeposition rims (2–3 nm), (2) composite (30–60 and (3) vesicular (60–80 nm). These characterized a combination zones. Zone I occupies outermost part modification, which contains elements that not included in unchanged substrate minerals, suggesting this zone is composed sputter deposits and/or impact...
Noble gas isotopes were measured in three rocky grains from asteroid Itokawa to elucidate a history of irradiation cosmic rays and solar wind on its surface. Large amounts helium (He), neon (Ne), argon (Ar) trapped various depths the observed, which can be explained by multiple implantations particles into grains, combined with preferential He loss caused frictional wear space-weathered rims grains. Short residence time less than 8 million years was implied for an estimate...
Hayabusa2 is an asteroid exploration mission to return surface samples of a near-Earth C-type (162173) 1999 JU3. Because asteroids are the evolved remnants planetesimals that were building blocks planets, detailed observation by spacecraft and analysis returned will provide direct evidence regarding planet formation dynamic evolution solar system. Moreover, expected preserve most pristine materials in system, mixture minerals, ice, organic matter interact with each other. Space missions only...
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...
Little is known about the origin of spectral diversity asteroids and what it says conditions in protoplanetary disk. Here, we show that samples returned from Cb-type asteroid Ryugu have Fe isotopic anomalies indistinguishable Ivuna-type (CI) chondrites, which are distinct all other carbonaceous chondrites. Iron isotopes, therefore, demonstrate CI chondrites formed a reservoir was different source regions asteroids. Growth migration giant planets destabilized nearby planetesimals ejected some...
The extraterrestrial materials returned from asteroid (162173) Ryugu consist predominantly of low-temperature aqueously formed secondary minerals and are chemically mineralogically similar to CI (Ivuna-type) carbonaceous chondrites. Here, we show that high-temperature anhydrous primary in chondrites exhibit a bimodal distribution oxygen isotopic compositions: 16O-rich (associated with refractory inclusions) 16O-poor chondrules). Both the probably inner solar protoplanetary disk were...
Chondrule-like objects and Ca-Al-rich inclusions (CAIs) are discovered in the retuned samples from asteroid Ryugu. Here we report results of oxygen isotope, mineralogical, compositional analysis chondrule-like CAIs. Three dominated by Mg-rich olivine 16O-rich -poor with Δ17O (=δ17O - 0.52 × δ18O) values ~ -23‰ -3‰, resembling what has been proposed as early generations chondrules. The likely to be melted amoeboid aggregates that escaped incorporation into 16O-poor chondrule precursor dust....
Samples from the carbonaceous asteroid (162173) Ryugu provide information on chemical evolution of organic molecules in early solar system. Here we show element partitioning major component ions by sequential extractions salts, carbonates, and phyllosilicate-bearing fractions to reveal primordial brine composition primitive asteroid. Sodium is dominant electrolyte salt fraction extract. Anions NH4+ are more abundant than carbonate phyllosilicate fractions, with molar concentrations order...
Polycyclic aromatic hydrocarbons (PAHs) contain ≲20% of the carbon in interstellar medium. They are potentially produced circumstellar environments (at temperatures ≳1000 kelvin), by reactions within cold (~10 kelvin) clouds, or processing carbon-rich dust grains. We report isotopic properties PAHs extracted from samples asteroid Ryugu and meteorite Murchison. The doubly-13C substituted compositions (Δ2×13C values) naphthalene, fluoranthene, pyrene 9 to 51‰ higher than values expected for a...
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– The Planetary Material Sample Curation Facility of JAXA (PMSCF/JAXA) was established in Sagamihara, Kanagawa, Japan, to curate planetary material samples returned from space conditions minimum terrestrial contaminants. performances for the curation Hayabusa‐returned had been checked with a series comprehensive tests and rehearsals. After Hayabusa spacecraft accomplished round‐trip flight asteroid 25143 Itokawa its reentry capsule Earth June 2010, brought back PMSCF/JAXA put...
Abstract Evaluating the molecular distribution of organic compounds in pristine extraterrestrial materials is cornerstone to understanding abiotic synthesis organics and allows us better understand diversity available during formation our solar system before origins life on Earth. In this work, we identify multiple solvent extracts asteroid Ryugu samples A0106 C0107 Orgueil meteorite using two-dimensional gas chromatography time-of-flight high resolution mass spectrometry (GC×GC–HRMS). Our...