Curriculum Vitaes
Profile Information
- Affiliation
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency
- Researcher number
- 00270439
- ORCID ID
https://orcid.org/0000-0003-4780-800X- J-GLOBAL ID
- 200901004756228297
- researchmap Member ID
- 5000050882
Research Areas
1Papers
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Ammonium-bearing phyllosilicate grains detected in Ryugu and Bennu samples via infrared spectroscopyNature Communications, May 6, 2026
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The Planetary Science Journal, 7(5) 114-114, May 1, 2026Abstract Aqueous alteration was one of the earliest geological processes in the solar system and significantly shaped the mineralogical diversity observed in primitive minor bodies. Carbonate minerals are reliable tracers of the physicochemical conditions during alteration processes on early planetesimals. We present a comprehensive characterization of carbonates in the returned samples of asteroids Ryugu and Bennu, performed using the MicrOmega near-infrared hyperspectral microscope. We identify two major carbonate species, dolomite (CaMg(CO 3 ) 2 ) and breunnerite ((Mg,Fe)CO 3 ), with similar relative abundances and mean elemental compositions on both asteroids, indicating analogous aqueous alteration pathways on their parent bodies. A general spatial separation of dolomite and breunnerite is observed, indicating that at size scales of 10–100 μ m, alteration conditions favored the precipitation of one species over the other. We interpret this as evidence for a spatially heterogeneous local water–rock ratio, suggesting that a high local water–rock ratio suppresses the formation of dolomite, instead favoring precipitation of breunnerites. Based on relative carbonate abundances, we conclude that chambers A (sampling the surface) and C (predominantly sampling the subsurface) of the Ryugu sample contain different mixtures of lithologies with different alteration degrees.
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METEORITICS & PLANETARY SCIENCE, Feb 23, 2026
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Meteoritics & Planetary Science, Jan, 2026
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Meteoritics & Planetary Science, Nov 25, 2025Abstract Analyzing primitive extraterrestrial samples from asteroids is key to understanding the evolution of the early solar system. The OSIRIS‐REx mission returned samples from the B‐type asteroid Bennu, providing a valuable opportunity to compare them with the Ryugu samples collected by the Hayabusa2 mission. This study examines the representativeness of a fraction of the Bennu samples, which was allocated from NASA to JAXA, by nondestructive characterization of their physical and spectral properties without atmospheric exposure. The reflectance and observed spectral features in the visible‐to‐infrared range of the Bennu sample resemble those from the spectroscopic analysis of different fractions. Additionally, we found differences in the slope of the visible range and band‐center of ~2.7 μm band between the samples and the asteroid surface, which could be explained by the degree of space weathering. A comparative analysis of the Bennu and Ryugu samples revealed spectral similarities, including absorption features indicative of Mg‐rich phyllosilicates, organics, and carbonates, without any evidence of sampling bias or terrestrial alteration. This finding can be used as a benchmark for subsequent Ryugu–Bennu comparative studies.
Misc.
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Abstracts of Annual Meeting of the Geochemical Society of Japan, 55 290-290, 20082010年の探査機はやぶさによる世界初の小惑星サンプルリターンに備え、日本初の惑星試料キュレーション設備を現在試験運用中である。設備はクリーンルーム(CR)と、設置した機器からなる。CRは独立排気系、ケミカルフィルターを使用し粒子的・化学的に清浄な環境を実現した。CRに導入している純水、窒素も高純度のものを準備した。2008年度は設備の総合試験、2009年度は、帰還リハーサルを実施する予定である。
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ASTRONOMY & ASTROPHYSICS, 472(1) L5-L8, Sep, 2007
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東京慈恵会医科大学雑誌, 122(4) 173, Jul 15, 2007type:article source:The Jikei University School of Medicine
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宇宙利用シンポジウム, 23rd 182-184, Mar, 2007We performed systematic impact cratering experiments in microgravity and vacuum environment with impact velocities larger than 100 m/sec and obtained data on diameter of crater formed in the environment. The experiments showed that the drop tower is an appropriate tool for studies of surface processes on small bodies. The result shows that the formation time and final diameter of crater formed in the glass beads or quartz sand layer are not controlled by the gravity.
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日本惑星科学会秋季講演会予稿集, 2007 63-63, 2007The SELENE will carry an optical instrument called Lunar Imager/Spectrometer (LISM). The LISM consists of three optical sub-instruments: the Terrain Camera (TC), the Multi-band Imager (MI), and the Spectral Profiler (SP). LISM will provide the data for scientific knowledge and possible utilization of the Moon. In this presentation, we will introduce the LISM operation plan with the planned SELENE orbit.
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日本惑星科学会秋季講演会予稿集, 2007 14-14, 2007Hayabusa 2 is an asteroid sample return mission following Hayabusa mission. This mission is now under study and mission target is c-type asteroid 1999JU3. From summer 2007 to April 2008 the observation from the earth is favorable conditions. This chance of observation is the first in 8 years from discovery. About 1999JU3 we had known only spectral type until now so we had observed lightcurve of it in July 2007. As a result we have found that its rotational period is about under 6 hours. This time, we will report about information of 1999JU3 we had get until now for example the result of lightcurve from July to September and about the result of AKARI in May and so on.
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日本惑星科学会秋季講演会予稿集, 2007 106-106, 2007The spin states of the small solar system objects can be altered by a net torque arising from the anisotropic thermal re-emission of sunlight on the surface, the so-called YORP effect. We present the results of ground-based observations of the near-Earth asteroid Itokawa, which is the target asteroid of the Hayabusa spacec, and its comparison with the theoretical model of Itokawa's YORP.
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日本惑星科学会秋季講演会予稿集, 2007 107-107, 2007The Hayabusa spacecraft, which was launched in May 2003, arrived at Asteroid Ito-kawa in September 2005, and it made observations of Itokawa and tried touch down in about three months.Hayabusa has four scientific instruments, that is Multi-Spectral Telescopic Imager (AMICA), Laser Altimeter (LIDAR), Near-Infrared Spectrometer (NIRS), and X-ray Fluorescence Spectrometer (XRS). The data obtained by these instruments were firstly analyzed by Hayabusa Science Team and some of the results have been pub-lished as scientific papers. At the same time, the science team was preparing to open them to the public and this work has almost been done. Therefore the science team release the data archives to public from April 24, 2007. All the scientific data that Hayabusa obtained are open to the public.The Hayabusa data archives can be accessed from the following web site:(URL) http://hayabusa.sci.isas.jaxa.jp/
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Abstracts for fall meeting of the Japanese Society for Planetary Science, 2007 106-106, 2007The spin states of the small solar system objects can be altered by a net torque arising from the anisotropic thermal re-emission of sunlight on the surface, the so-called YORP effect. We present the results of ground-based observations of the near-Earth asteroid Itokawa, which is the target asteroid of the Hayabusa spacec, and its comparison with the theoretical model of Itokawa's YORP.
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Abstracts for fall meeting of the Japanese Society for Planetary Science, 2007 107-107, 2007The Hayabusa spacecraft, which was launched in May 2003, arrived at Asteroid Ito-kawa in September 2005, and it made observations of Itokawa and tried touch down in about three months.Hayabusa has four scientific instruments, that is Multi-Spectral Telescopic Imager (AMICA), Laser Altimeter (LIDAR), Near-Infrared Spectrometer (NIRS), and X-ray Fluorescence Spectrometer (XRS). The data obtained by these instruments were firstly analyzed by Hayabusa Science Team and some of the results have been pub-lished as scientific papers. At the same time, the science team was preparing to open them to the public and this work has almost been done. Therefore the science team release the data archives to public from April 24, 2007. All the scientific data that Hayabusa obtained are open to the public.The Hayabusa data archives can be accessed from the following web site:(URL) http://hayabusa.sci.isas.jaxa.jp/
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Abstracts for fall meeting of the Japanese Society for Planetary Science, 2007 14-14, 2007Hayabusa 2 is an asteroid sample return mission following Hayabusa mission. This mission is now under study and mission target is c-type asteroid 1999JU3. From summer 2007 to April 2008 the observation from the earth is favorable conditions. This chance of observation is the first in 8 years from discovery. About 1999JU3 we had known only spectral type until now so we had observed lightcurve of it in July 2007. As a result we have found that its rotational period is about under 6 hours. This time, we will report about information of 1999JU3 we had get until now for example the result of lightcurve from July to September and about the result of AKARI in May and so on.
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Abstracts for fall meeting of the Japanese Society for Planetary Science, 2007 63-63, 2007The SELENE will carry an optical instrument called Lunar Imager/Spectrometer (LISM). The LISM consists of three optical sub-instruments: the Terrain Camera (TC), the Multi-band Imager (MI), and the Spectral Profiler (SP). LISM will provide the data for scientific knowledge and possible utilization of the Moon. In this presentation, we will introduce the LISM operation plan with the planned SELENE orbit.
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Proceedings of the International Astronomical Union, 2(236) 261-266, Aug, 2006
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SCIENCE, 312(5778) 1350-1353, Jun, 2006
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SCIENCE, 312(5778) 1334-1338, Jun, 2006
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Proceedings of 25th ISTS meeting 25, 2006
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Nature (in press), 2006 Peer-reviewed
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Proceedings of 25th ISTS meeting 2006-k-25, 2006
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Abstract of COSPAR Scientific Assembly 36, 2006
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37th Lunar and Planetary Science Conference 37, 2352, 2006
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Abstract of Lunar and Planetary Science Conference 37, 2352, 2006
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Abstracts for fall meeting of the Japanese Society for Planetary Science, 2006 7-7, 2006The observation of Asteroid Itokawa by Hayabusa spacecraft has brought us a lot of new knowledge for very small (about 500m in length) S-type asteroid. We already have started to consider next space mission to small bodies in the solar system. For the next asteroid mission, we would like to explore C-type asteroid, which is also major type in the asteroid belt. This type of asteroid is supposed to have organic matter or water more than S-type asteroid, and it is important to study the material related to life. In this paper, we present the current plan for the next exploration to asteroids. We also want to encourage many researchers to join our asteroid mission.
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宇宙科学技術連合講演会講演集(CD-ROM), 50th 2H09, 2006
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日本惑星科学会秋季講演会予稿集, 2006 24-6, 2006In 2005, HAYABUSA observed an S-type asteroid Itokawa (with size of 550m) by onboard camera AMICA (Saito et al., 2006). Almost 80% of the surface is rough and boulder-rich but it has weathered spectrum on average. Optically, the surface of Itokawa is divided into brighter (and bluer) areas and darker (and redder) areas. In rough zones, dark boulder-rich surfaces usually superpose on bright materials. We can interpret impact-induced seismic shaking or shaking at planetary encounters should remove dark weathered boulder-rich surface to expose underlying relatively fresh bright area. High resolution images indicate that these bouldered surface are optically weathered. To check the possibility that the rock surface could be weathered, we irradiate pulse laser on meteorite fragments with cut flat surface under vacuum. For comparison, we also irradiate pellet samples where particle size is smaller than 125 microns. Fresh meteorites NWA1794 and Bensour were chosen because spectral observation of Itokawa suggested its similarity with LL5 and LL6 chondrites. As expected, significant darkening and reddening are observed at irradiating pellet samples.
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Abstracts for fall meeting of the Japanese Society for Planetary Science, 2006 26-26, 2006Impact cratering experiments in microgravity environment were performed using a drop tower. The results showed no gravity effect. Details of experimental procedures and results will be presented at the session.
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宇宙科学技術連合講演会講演集(CD-ROM), 50th 3G16, 2006
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宇宙科学技術連合講演会講演集(CD-ROM), 50th 2H14, 2006
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日本惑星科学会秋季講演会予稿集, 2006 23-5, 2006Concerning the controversy that the visible and near-infrared (NIR) reflectance spectra of the S-type asteroids and ordinary chondrites which are the most abundant in the near-Earth region do not match with each other, especially the hypothesis of space weathering had been strongest as the explanation in the past. As the result of visible and NIR observations of an S-type asteroid 25143 Itokawa by the Hayabusa Mission, such idea has become even more assuring. Itokawa consists of bright and dark portions in general, and both of those regions in any scale show spectra indicating a mineral assemblage consistent with only those of LL chondrites among all known meteorites, wherein the only differences are the mean optical path length and the degree of space weathering. The fact that an asteroid which is made of an LL-chondrite material and space-weathered to look as an S-type asteroid suggests that many more S asteroids made of ordinary-chondrite materials (including H and L types) exist in the near-Earth region.
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日本惑星科学会秋季講演会予稿集, 2006 41-23, 2006The near-infrared spectrometer (NIRS) on the Hayabusa spacecraft obtained spatially resolved reflectance spectra of 25143 Itokawa between September 12 and November 24, 2005. In this study, we had modeled a photometric function of the asteroid surface based on the observed spectral data and have investigated the surface heterogeneity of asteroid Itokawa.
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日本惑星科学会秋季講演会予稿集, 2006 21-3, 2006The laser altimetry (LIDAR) aboard the Hayabusa spacecraft measured the surface topography of the asteroid Itokawa and the mass calculated by spacecraft position without orbiting. The mass of Itokawa was estimated as 3.5 x 1010 kg, implying a bulk density of 1.9 g/cm3 and a bulk porosity of -40% when assuming chondritic meteorite composition(density of 3.2 g/cm3) (Abe et al, Science, 2006). In order to investigate the origin of Itokawa, especially for the interior structure and surface characteristics, we will discuss about the principal axis of inertia calculated by Itokawa's shape model and also present a 50m sized biggest bouldar, named 'Yoshinodai', on the surface by using near-infrared and visible spectra.
Books and Other Publications
3Presentations
2Research Projects
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Apr, 2019 - Mar, 2022
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Apr, 2016 - Mar, 2019
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, 2006 - 2007
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, 2005 - 2006
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, 2002 - 2003
