Yuichiro Cho
A5031008390- Astro and Planetary Science
- Planetary Science and Exploration
- Isotope Analysis in Ecology
- Geology and Paleoclimatology Research
- Laser-induced spectroscopy and plasma
- Geological and Geochemical Analysis
- Space Exploration and Technology
- Space Science and Extraterrestrial Life
- Space Satellite Systems and Control
- Nuclear Physics and Applications
- Stellar, planetary, and galactic studies
- Landslides and related hazards
- Geochemistry and Geologic Mapping
- Spacecraft Design and Technology
- Atmospheric Ozone and Climate
- earthquake and tectonic studies
- High-pressure geophysics and materials
- Spaceflight effects on biology
- Solar and Space Plasma Dynamics
- Astronomical Observations and Instrumentation
- Spacecraft and Cryogenic Technologies
- Archaeology and ancient environmental studies
- Dam Engineering and Safety
- Urban and spatial planning
- Optical Polarization and Ellipsometry
The University of Tokyo
2011-2024
Rikkyo University
2015-2024
Tokyo Medical and Dental University
2007-2024
The Japanese Society of Gastroenterological Surgery
2021-2024
Iwate Medical University
2021-2024
Onomichi General Hospital
2024
Hiroshima University
2024
Tokyo University of Science
2011-2023
International Society of Automation
2023
Japan Agency for Marine-Earth Science and Technology
2023
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...
The Hayabusa2 spacecraft investigated the small asteroid Ryugu, which has a rubble-pile structure. We describe an impact experiment on Ryugu using Hayabusa2's Small Carry-on Impactor. produced artificial crater with diameter >10 meters, semicircular shape, elevated rim, and central pit. Images of resulting ejecta were recorded by Deployable CAMera 3 for >8 minutes, showing growth curtain (the outer edge ejecta) deposition onto surface. was asymmetric heterogeneous it never fully detached...
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...
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 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...
In 2018, the Japanese spacecraft Hayabusa2, arrived at small asteroid Ryugu. The surface of this C-type is covered with numerous boulders whose size and shape distributions are investigated in study. Using a few hundred Optical Navigation Camera (ONC) images pixel scale approximately 0.65 m, we focus on greater than 5 m diameter. Smaller also considered using five arbitrarily chosen ONC close-up scales ranging from 0.7 to 6 cm. Across entire area (~2.7 km2) Ryugu, nearly 4400 larger were...
Carbonaceous asteroids, such as (101955) Bennu, preserve material from the early Solar System, including volatile compounds and organic molecules. We report spacecraft imaging spectral data collected during after retrieval of a sample Bennu’s surface. The sampling event mobilized rocks dust into debris plume, excavating 9-meter-long elliptical crater. This exposed is darker, spectrally redder, more abundant in fine particulates than original bulk density displaced subsurface was 500 to 700...
Context. The Hayabusa2 spacecraft launched by Japan Aerospace Exploration Agency has been conducting observations of the asteroid (162173) Ryugu since June 2018. Telescopic Optical Navigation Camera (ONC-T) onboard obtained thousands images under a variety illumination and viewing conditions. Aims. Our objective is to examine validate camera calibration, derive photometric correction for creating global albedo maps, interpret modeling results characterize surface Ryugu. Methods. We observed...
Abstract Ryugu is a carbonaceous rubble-pile asteroid visited by the Hayabusa2 spacecraft. Small rubble pile asteroids record thermal evolution of their much larger parent bodies. However, recent space weathering and/or solar heating create ambiguities between uppermost layer observable remote-sensing and pristine material from body. observations find that on (162173) both north south pole regions preserve least processed weathering, which spectrally blue chondritic with 0–3% deep 0.7-µm...
Abstract Mineralogy is the key to understanding origin of Phobos and its position in evolution Solar System. In situ Raman spectroscopy on an important tool achieve scientific objectives Martian Moons eXploration (MMX) mission, maximize merit sample return by characterizing mineral composition heterogeneity surface Phobos. Conducting harsh environment requires a very sensitive, compact, lightweight, robust instrument that can be carried compact MMX rover. this context, spectrometer for...
Abstract Returned samples from Cb-type asteroid (162173) Ryugu exhibit very dark spectra in visible and near-infrared ranges, generally consistent with the Hayabusa2 observations. A critical difference is that a structural water absorption of hydrous silicates around twice as deep returned compared those Ryugu’s surface, suggesting surface more dehydrated. Here we use laboratory experiments data to indicate spectral differences between are best explained if has (1) higher porosity, (2)...
162173 Ryugu, the target of Hayabusa2, has a round shape with an equatorial ridge, which is known as spinning top-shape. A strong centrifugal force likely contributor to Ryugu's top-shaped features. Observations by Optical Navigation Camera onboard Hayabusa2 show unique longitudinal variation in geomorphology; western side this asteroid, later called bulge, smooth surface and sharp compared other side. Here, we propose structural deformation process that generated bulge. Applying...
A compact Raman spectrometer [1] was developed for in-situ science on Phobos with the IDEFIX rover [2], which will be launched as part of JAXA’s Martian Moon eXploration (MMX) mission in 2026. The MMX is dedicated to study two moons, and Deimos, aim better understanding their origin evolution [3, 4]. Orbital observations main spacecraft rover complemented by returning samples (>10 g) from surface back Earth. expected land between late 2028 early 2029,...
The crater retention ages of the mare deposits within Orientale multi‐ring impact basin are investigated using 10‐m resolution images obtained by SELENE (Kaguya) spacecraft, in order to constrain volcanic history Moon around nearside‐farside boundary. Precise crater‐counting analyses reveal that region much younger than previously estimated: ∼2.9 Ga basalt eastern part Mare and ∼1.8–2.2 Lacus Veris Autumni, maria along northeastern rings basin. latter age estimates indicate experienced...
Images from the Optical Navigation Camera system (ONC) onboard Hayabusa2 spacecraft show MASCOT lander during its descent to surface of asteroid (162173) Ryugu. We used results a previous stereo-photogrammetric analysis that provided precise ONC image orientation data (camera position and pointing), orthoimages, an ONC-based 3D model combine them with visibilities itself shadow on-ground within images. integrated additional information instruments (MASMag, MARA, MASCam) derived MASCOT’s...