The University of Tokyo · Physics and Astronomy
Professor Yuichiro Cho's research lab specializes in planetary science and in situ analytical techniques for planetary exploration, focusing on the mineralogy, surface evolution, and geochronology of airless bodies such as asteroids, moons, and planets. The lab develops advanced instruments—such as compact Raman spectrometers and K-Ar isochron systems—designed for space missions, emphasizing technical feasibility and scientific return in extreme environments. Current research integrates remote sensing, sample analysis, and experimental validation to understand planetary formation and volcanic history, particularly through data from lunar and asteroid sample return missions like MMX and Hayabusa2.
Figures are computed from collected data and may differ slightly.
Abstract Mineralogy is the key to understanding the origin of Phobos and its position in the evolution of the Solar System. In situ Raman spectroscopy on Phobos is an important tool to achieve the scientific objectives of the Martian Moons eXploration (MMX) mission, and maximize the scientific merit of the sample return by characterizing the mineral composition and heterogeneity of the surface of Phobos. Conducting in situ Raman spectroscopy in the harsh environment of Phobos requires a very sen
The crater retention ages of the mare deposits within the Orientale multi‐ring impact basin are investigated using 10‐m resolution images obtained by the SELENE (Kaguya) spacecraft, in order to constrain the volcanic history of the Moon around the nearside‐farside boundary. Precise crater‐counting analyses reveal that mare deposits in the Orientale region are much younger than previously estimated: ∼2.9 Ga mare basalt in the eastern part of Mare Orientale and ∼1.8–2.2 Ga mare deposits in Lacus V
Abstract Crater morphology and surface age of asteroid (162173) Ryugu are characterized using the high‐resolution images obtained by the Hayabusa2 spacecraft. Our observations reveal that the abundant boulders on and under the surface of the rubble‐pile asteroid affect crater morphology. Most of the craters on Ryugu exhibit well‐defined circular depressions, unlike those observed on asteroid Itokawa. The craters are typically outlined by boulders remaining on the rim. Large craters (diameter >
Our experimental results demonstrate that accurate and precise measurements are possible using the KArLE approach on basaltic rocks, which are ubiquitous on planetary surfaces, and are useful in addressing a wide range of questions in planetary science.
In situ radiogenic isotope measurements to obtain the absolute age of geologic events on planets are of great scientific value. In particular, K-Ar isochrons are useful because of their relatively high technical readiness and high accuracy. Because this isochron method involves spot-by-spot K measurements using laser-induced breakdown spectroscopy (LIBS) and simultaneous Ar measurements with mass spectrometry, LIBS measurements are conducted under a high vacuum condition in which emission intens
Hayabusa2 collected 5.4 g of samples from asteroid (162173) Ryugu and brought them back to Earth. Obtaining multiband images of these samples with spectral bands comparable to those used for remote-sensing observations is important for characterizing the collected samples and examining how representative they are compared with spacecraft observations of Ryugu. In this study, we constructed a multiband microscopic camera system that enables both visual multispectral imaging at 390 (ul), 475 (b),
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