Changkun Park
A5052735068- Astro and Planetary Science
- Planetary Science and Exploration
- Isotope Analysis in Ecology
- High-pressure geophysics and materials
- Geological and Geochemical Analysis
- Geology and Paleoclimatology Research
- Geochemistry and Geologic Mapping
- Spacecraft and Cryogenic Technologies
- Stellar, planetary, and galactic studies
- Nuclear Physics and Applications
- Mineralogy and Gemology Studies
- Geomagnetism and Paleomagnetism Studies
- Space Exploration and Technology
- Hydrocarbon exploration and reservoir analysis
- Groundwater and Isotope Geochemistry
- Muon and positron interactions and applications
- Satellite Image Processing and Photogrammetry
- Protist diversity and phylogeny
- Glass properties and applications
- X-ray Spectroscopy and Fluorescence Analysis
- earthquake and tectonic studies
- Material Dynamics and Properties
- Cassava research and cyanide
- Paleontology and Evolutionary Biology
- Radioactive contamination and transfer
Korea Polar Research Institute
2016-2024
Planetary Science Institute
2024
University of California, Davis
2024
Tohoku University
2024
Korea University of Science and Technology
2024
University of Hawaiʻi at Mānoa
2012-2017
Hokkaido University
2011-2012
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...
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...
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...
Chaetognaths, with their characteristic grasping spines, are the oldest known pelagic predators, found in lowest Cambrian (Terreneuvian). Here, we describe a large stem chaetognath,
Abstract Recent discoveries of fossil nervous tissue in Cambrian fossils have allowed researchers to trace the origin and evolution complex arthropod head brain based on stem groups close clade, rather than extant, highly derived members. Here we show that Kerygmachela from Sirius Passet, North Greenland, a primitive stem-group euarthropod, exhibits diminutive (protocerebral) innervates both eyes frontal appendages. It has been surmised, developmental evidence, ancestor vertebrates...
Preliminary analyses of asteroid Ryugu samples show kinship to aqueously altered CI (Ivuna-type) chondrites, suggesting similar origins. We report identification C-rich, particularly primitive clasts in that contain preserved presolar silicate grains and exceptional abundances SiC isotopically anomalous organic matter. The high abundance (104 ppm) indicates the clast escaped extensive alteration. 5 10 times higher (~235 ppm), N-rich matter, organics with N isotopic anomalies (1.2%), C (0.2%)...
Studies of material returned from Cb asteroid Ryugu have revealed considerable mineralogical and chemical heterogeneity, stemming primarily brecciation aqueous alteration. Isotopic anomalies could also been affected by delivery exogenous clasts mobilization soluble elements. Here, we show that isotopic for mildly Cr are highly variable in CI chondrites, whereas those Ti relatively uniform. This variation isotope ratios is most likely due to physicochemical fractionation between 54Cr-rich...
The isotopic compositions of samples returned from Cb-type asteroid Ryugu and Ivuna-type (CI) chondrites are distinct other carbonaceous chondrites, which has led to the suggestion that Ryugu/CI formed in a different region accretion disk, possibly around orbits Uranus Neptune. We show that, like for Fe, CI also have indistinguishable Ni isotope anomalies, differ those chondrites. propose this unique Fe composition reflects efficiencies small FeNi metal grains among chondrite parent bodies....
Iron is one of the most studied chemical elements due to its sociotechnological and planetary importance; hence, understanding structural transition dynamics vital interest. By combining a short pulse optical laser an ultrashort free electron pulse, we have observed subnanosecond iron from high-quality x-ray diffraction data measured at 50-ps intervals up 2500 ps. We unequivocally identify three-wave structure during initial compression two-wave decaying shock, involving all known types (α-,...
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...
Ryugu C A CI CM CV CO 44/40 Ca SRM915a (age corrected)The Hayabusa2 spacecraft has returned samples from the Cb-type asteroid (162173) to Earth.Previous petrological and chemical analyses support a close link between chondrites that are presumed be chemically most primitive meteorites with solar-like composition.However, highly enriched in compared typical chondrites.To identify cause of this discrepancy, here we report stable isotopic data (expressed as δ ) for collected two sites.We found...
Abstract– High‐precision isotope imaging analyses of reversely zoned melilite crystals in the gehlenitic mantle Type A CAI ON01 Allende carbonaceous chondrite reveal that there are four types oxygen isotopic distributions within single crystals: (1) uniform depletion 16 O (δ 18 ≈ −10‰), (2) enrichment −40‰), (3) variations composition from O‐poor core to O‐rich rim −10‰ −30‰, −20‰ −45‰, and −35‰) with decreasing åkermanite content, (4) ≥ −10‰) along crystal rim. Hibonite, spinel, perovskite...
Abstract Oxygen 3‐isotope ratios of magnetite and carbonates in aqueously altered carbonaceous chondrites provide important clues to understanding the evolution fluid asteroidal parent bodies. We conducted oxygen analyses magnetite, dolomite, breunnerite two sections asteroid Ryugu returned samples, A0058 C0002, using a secondary ion mass spectrometer (SIMS). Magnetite was analyzed by lower primary energy that reduced instrumental biases due crystal orientation effect. found groups data...
Abstract Rock fragments of the Cb-type asteroid Ryugu returned to Earth by JAXA Hayabusa2 mission share mineralogical, chemical, and isotopic properties with Ivuna-type (CI) carbonaceous chondrites. Similar CI chondrites, these underwent extensive aqueous alteration consist predominantly hydrous minerals likely formed in presence liquid water on parent asteroid. Here we present an situ analytical survey performed secondary ion mass spectrometry from which have estimated D/H ratio Ryugu’s...
Abstract We report an occurrence of hexagonal CaAl 2 Si O 8 (dmisteinbergite) in a compact type A calcium‐aluminum‐rich inclusion ( CAI ) from the CV 3 (Vigarano‐like) carbonaceous chondrite Northwest Africa 2086. Dmisteinbergite occurs as approximately 10 μm long and few micrometer‐thick lath‐shaped crystal aggregates altered parts , is associated with secondary nepheline, sodalite, Ti‐poor Al‐diopside, grossular, Fe‐rich spinel. Spinel only primary mineral that retained its original...