研究者業績
基本情報
- 所属
- 国立研究開発法人宇宙航空研究開発機構 宇宙科学研究所 宇宙飛翔工学研究系 教授東京大学 大学院工学系研究科 航空宇宙工学専攻 教授
- 学位
- 博士（工学）(2003年3月 東京大学)
- J-GLOBAL ID
- 200901005218518613
- researchmap会員ID
- 5000069162
- 外部リンク
研究分野
1経歴
5-
2020年1月 - 現在
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2014年7月 - 2019年12月
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2008年8月 - 2009年3月
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2008年3月 - 2008年7月
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2003年4月
学歴
3-
1998年4月 - 2003年3月
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1996年4月 - 1998年3月
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1994年4月 - 1996年3月
主要な受賞
29-
2021年3月
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2020年12月
論文
458-
Earth, Planets and Space 75(1) 2023年1月9日Abstract Sample-return missions allow the study of materials collected directly from celestial bodies, unbiased by atmospheric entry effects and/or terrestrial alteration and contamination phenomena, using state-of-the-art techniques which are available only in a laboratory environment—but only if the collected material stays pristine. The scarcity of outer-space unaltered material recovered until now makes this material extremely precious for the potential scientific insight it can bring. To maximize the scientific output of current and future sample-return missions, the scientific community needs to plan for ways of storing, handling, and measuring this precious material while preserving their pristine state for as long as the ‘invasiveness’ of measurements allows. In July 2021, as part of the Hayabusa2 (JAXA) “Stone” preliminary examination team, we received several microscopic particles from the asteroid Ryugu, with the goal of performing IR hyper-spectral imaging and IR micro-tomography studies. Here, we describe the sample transfer, handling methods and analytical pipeline we implemented to study this very precious material while minimizing and surveilling their alteration history on Earth. Graphical Abstract
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Science 379(6634) 786-+ 2023年Carbonaceous meteorites are thought to be fragments of C-type (carbonaceous) asteroids. Samples of the C-type asteroid (162173) Ryugu were retrieved by the Hayabusa2 spacecraft. We measured the mineralogy and bulk chemical and isotopic compositions of Ryugu samples. The samples are mainly composed of materials similar to those of carbonaceous chondrite meteorites, particularly the CI (Ivuna-type) group. The samples consist predominantly of minerals formed in aqueous fluid on a parent planetesimal. The primary minerals were altered by fluids at a temperature of 37 degrees +/- 10 degrees C, about 5.2(-0.7)(+0.8) million (statistical) or 5.2(-2.1)(+1.6) million (systematic) years after the formation of the first solids in the Solar System. After aqueous alteration, the Ryugu samples were likely never heated above similar to 100 degrees C. The samples have a chemical composition that more closely resembles that of the Sun's photosphere than other natural samples do.
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Proceedings of the International Astronautical Congress, IAC 2023-October 2023年
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Journal of Analytical Atomic Spectrometry 2023年Mass spectrometry of noble gas isotopes from the asteroid materials delivered by robotic space missions requires high sensitivity, high ion transmission, low detection limit, and other characteristics not readily available in commercial instruments.
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TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN 21 29-35 2023年
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TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN 21 19-28 2023年
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Nature Astronomy 7(1) 29-38 2022年12月19日 査読有り
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Nature Astronomy 2022年12月19日Abstract Without a protective atmosphere, space-exposed surfaces of airless Solar System bodies gradually experience an alteration in composition, structure and optical properties through a collective process called space weathering. The return of samples from near-Earth asteroid (162173) Ryugu by Hayabusa2 provides the first opportunity for laboratory study of space-weathering signatures on the most abundant type of inner solar system body: a C-type asteroid, composed of materials largely unchanged since the formation of the Solar System. Weathered Ryugu grains show areas of surface amorphization and partial melting of phyllosilicates, in which reduction from Fe3+ to Fe2+ and dehydration developed. Space weathering probably contributed to dehydration by dehydroxylation of Ryugu surface phyllosilicates that had already lost interlayer water molecules and to weakening of the 2.7 µm hydroxyl (–OH) band in reflectance spectra. For C-type asteroids in general, this indicates that a weak 2.7 µm band can signify space-weathering-induced surface dehydration, rather than bulk volatile loss.
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Frontiers in Space Technologies 3 2022年12月8日There are a number of deep space probes that are currently in operation with diverse destinations and objectives. For example, the Japanese Hayabusa2 and the U.S. OSIRIS-REx missions are both sample returns, targeting different near-Earth asteroids. Europe’s ExoMars and the U.S. Perseverance are orbiting and roving Mars as precursors of future manned explorations. Conventionally, deep space missions require dedicated launch vehicles for each mission. The interplanetary Earth departure trajectory from the low Earth orbit (LEO) usually lacks flexibility and efficiency. Furthermore, innovative and reusable launch systems have been researched and developed by multiple organizations including private sector organizations such as SpaceX and Blue Origin. It is expected that the unit cost per launch weight to LEO be significantly reduced by rideshare mass transportation executed by using reusable mega launchers in the near future. This study aims to fill the transportation gap between LEO and deep space by realizing a flexible and economical interplanetary Earth departure without sacrificing the arbitrariness of LEO, target V-infinity vector, and target Earth departure epoch. Thus, the one-revolution Earth free-return orbit (1rEFRO) and the consequent Earth gravity assist (EGA) are introduced to separate the velocity increment and direction adjustment. The planetary free-return and EGAs are common in interplanetary missions; however, a comprehensive study on the flexibility, economic efficiency, and arbitrariness of the sequence (1rEFRO + EGA) originating from LEO was not explicitly found. After describing the necessary coordinate frames, LEO’s orbital elements, 1rEFRO, and the terms ‘flexibility’ and ‘economic efficiency’ are defined in Section 2. Then in Section 3, the two-body-based preliminary orbit design method is proposed and formulated. Section 4 aims to reveal LEO’s comprehensiveness as efficient parking orbits when adopting the 1rEFRO + EGA sequence, using the newly proposed “ LEO i-Ω diagram”. Section 5 describes a detailed orbit design constructed based on multi-body propagation and optimization to confirm the feasibility, flexibility, and economics of the solution and the usefulness of the initial solution given by the preliminary design method formulated in Section 3.
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Science Advances 8(50) 2022年12月
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Earth, Planets and Space 74(1) 2022年12月
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Earth, Planets and Space 74(1) 2022年12月
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Frontiers in Space Technologies 3 2022年11月23日On 5 April 2019, the Hayabusa 2 spacecraft performed the first successful artificial impact experiment on an asteroid. The Small Carry-on Impactor (SCI) device was deployed at an altitude of 500 m above Ryugu’s surface. The 2 kg copper projectile hit Ryugu’s surface in 40 min and caused the formation of an artificial crater 14.5 m in diameter. Once the SCI was deployed, the Hayabusa 2 spacecraft performed a two-week escape trajectory reaching altitudes as far as 120 km from Ryugu. The spacecraft then returned to its nominal position at 20 km altitude (Home-Position) from Ryugu for hovering control. This was done to prevent ejecta particles from seriously damaging the spacecraft and compromising its functionality. In this article, we present a method to forecast the daily probability of spacecraft damage along the selected nominal escape trajectory due to the debris cloud formed by an artificial impact. The result of the damage analysis confirmed that the selected escape trajectory experienced a small number of particle collisions under the design threshold, which would not have resulted in damage. Indeed, no damage was reported on the Hayabusa 2 spacecraft and it kept operating normally after the SCI operation. The method here presented serves as a guideline for post-impact mission operations to forecast and estimate the probability of damage to spacecraft or CubeSats operating near a small celestial body after an artificial impact experiment has occurred.
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Earth, Planets and Space 74(1) 2022年11月4日Abstract A fundamental parameter-based quantification scheme for confocal XRF was applied to sub-micron synchrotron radiation X-ray fluorescence (SR-XRF) data obtained at the beamline P06 of the Deutsches Elektronen-Synchrotron (DESY, Hamburg, Germany) from two sections C0033-01 and C0033-04 that were wet cut from rock fragment C0033 collected from Cb-type asteroid (162173) Ryugu by JAXA’s Hayabusa2 mission. Trace-element quantifications show that C0033 bulk matrix is CI-like, whereas individual mineral grains (i.e., magnetite, pyrrhotite, dolomite, apatite and breunnerite) show, depending on the respective phase, minor to strong deviations. The non-destructive nature of SR-XRF coupled with a new PyMca (a Python toolkit for XRF data analysis)-based quantification approach, performed in parallel with the synchrotron experiments, proves to be an attractive tool for the initial analysis of samples from return missions, such as Hayabusa2 and OSIRIS-REx, the latter returning material from a B-type asteroid (101955) Bennu in 2023. Graphical Abstract
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Science Advances 8(46) 2022年11月
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Journal of Geophysical Research: Planets 127(11) 2022年11月
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Science 379(6634) 2022年10月20日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 of Ryugu were retrieved by the Hayabusa2 spacecraft. We measure noble gas and nitrogen isotopes in Ryugu samples, finding they are dominated by pre-solar and primordial components, incorporated during Solar System formation. Noble gas concentrations are higher than those in Ivuna-type carbonaceous (CI) chondrite meteorites. Several host phases of isotopically distinct nitrogen have heterogeneous abundances between the samples. Our measurements support a close relationship between Ryugu and CI chondrites. Noble gases produced by galactic cosmic rays, indicating ~5 Myr exposure, and from implanted solar wind, record the recent irradiation history of Ryugu after it migrated to its current orbit.
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Geochemical Perspectives Letters 24 1-6 2022年10月
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Science 379(6634) 2022年9月22日Samples of the carbonaceous asteroid Ryugu were brought to Earth by the Hayabusa2 spacecraft. We analyzed seventeen Ryugu samples measuring 1-8 mm. CO 2 -bearing water inclusions are present within a pyrrhotite crystal, indicating that Ryugu’s parent asteroid formed in the outer Solar System. The samples contain low abundances of materials that formed at high temperatures, such as chondrules and Ca, Al-rich inclusions. The samples are rich in phyllosilicates and carbonates, which formed by aqueous alteration reactions at low temperature, high pH, and water/rock ratios < 1 (by mass). Less altered fragments contain olivine, pyroxene, amorphous silicates, calcite, and phosphide. Numerical simulations, based on the mineralogical and physical properties of the samples, indicate Ryugu’s parent body formed ~ 2 million years after the beginning of Solar System formation.
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Nature Astronomy 6(10) 1172-1177 2022年9月1日
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2022年8月29日Abstract Chondrule-like objects and Ca-Al-rich inclusions (CAIs) are discovered in the retuned samples from asteroid Ryugu. Three chondrule-like objects, which are 16O-rich and -poor with D17O (= d17O – 0.52 × d18O) values of ~ − 23‰ and ~ − 3‰, are dominated by Mg-rich olivine, resembling what proposed as earlier generations of chondrules. The 16O-rich objects are likely to be melted amoeboid olivine aggregates that escaped from incorporation into 16O-poor chondrule precursor dust. Two CAIs composed of spinel, hibonite, and perovskite are 16O-rich with D17O of ~ − 23‰ and possibly as old as the oldest CAIs. The chondrule-like objects and CAIs (< 30 µm) are as small as those from comets, suggesting radial transport favoring smaller objects from the inner solar nebula to the formation location of the Ryugu original parent body, which is farther from the Sun and scarce in chondrules. The transported objects may have been mostly destroyed during aqueous alteration.
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Nature Astronomy 6(10) 1163-1171 2022年8月15日Abstract Volatile and organic-rich C-type asteroids may have been one of the main sources of Earth’s water. Our best insight into their chemistry is currently provided by carbonaceous chondritic meteorites, but the meteorite record is biased: only the strongest types survive atmospheric entry and are then modified by interaction with the terrestrial environment. Here we present the results of a detailed bulk and microanalytical study of pristine Ryugu particles, brought to Earth by the Hayabusa2 spacecraft. Ryugu particles display a close compositional match with the chemically unfractionated, but aqueously altered, CI (Ivuna-type) chondrites, which are widely used as a proxy for the bulk Solar System composition. The sample shows an intricate spatial relationship between aliphatic-rich organics and phyllosilicates and indicates maximum temperatures of ~30 °C during aqueous alteration. We find that heavy hydrogen and nitrogen abundances are consistent with an outer Solar System origin. Ryugu particles are the most uncontaminated and unfractionated extraterrestrial materials studied so far, and provide the best available match to the bulk Solar System composition.
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2022年8月3日Abstract Hayabusa2 spacecraft successfully collected rock samples through two touchdowns from the surface of C-type near-Earth asteroid 162173 Ryugu and brought them back to Earth in 2020. At the Extraterrestrial Sample Curation Center in JAXA, we performed initial description to all samples to obtain the fundamental information and prepare the database for sample allocation. We propose morphological classifications for the returned samples based on the initial description of 205 grains described in the first 6 months. The returned samples can be distinguished by four morphological characteristics: dark, glossy, bright, and white. According to coordinated study of initial description and detailed investigation by scanning electron microscopy and X-ray diffraction analysis in this study, these features reflect the differences in the degree of space weathering and mineral assemblages. The degree of space weathering of the four studied grains is heterogeneous: weak for A0042 (dark group) and C0041 (white group); moderate for C0094 (glossy); and severe for A0017 (bright). The white phase in a grain belonging to white group is identified as large carbonate minerals. This is the first effort to classify Ryugu returned samples. Based on these results, researchers can estimate sample characteristics only from the information on the JAXA curation public database. It could be an important reference for sample selection for further investigation.
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The Astrophysical Journal Letters 935 L3 2022年8月1日 査読有り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. We report the detection of all major presolar grain types with O- and C-anomalous isotopic compositions typically identified in carbonaceous chondrite meteorites: 1 silicate, 1 oxide, 1 O-anomalous supernova grain of ambiguous phase, 38 SiC, and 16 carbonaceous grains. At least two of the carbonaceous grains are presolar graphites, whereas several grains with moderate C isotopic anomalies are probably organics. The presolar silicate was located in a clast with a less altered lithology than the typical extensively aqueously altered Ryugu matrix. The matrix-normalized presolar grain abundances in Ryugu are ${4.8}_{-2.6}^{+4.7}$ ppm for O-anomalous grains, ${25}_{-5}^{+6}$ ppm for SiC grains, and ${11}_{-3}^{+5}$ ppm for carbonaceous grains. Ryugu is isotopically and petrologically similar to carbonaceous Ivuna-type (CI) chondrites. To compare the in situ presolar grain abundances of Ryugu with CI chondrites, we also mapped Ivuna and Orgueil samples and found a total of 15 SiC grains and 6 carbonaceous grains. No O-anomalous grains were detected. The matrix-normalized presolar grain abundances in the CI chondrites are similar to those in Ryugu: ${23}_{-6}^{+7}$ ppm SiC and ${9.0}_{-3.6}^{+5.4}$ ppm carbonaceous grains. Thus, our results provide further evidence in support of the Ryugu–CI connection. They also reveal intriguing hints of small-scale heterogeneities in the Ryugu samples, such as locally distinct degrees of alteration that allowed the preservation of delicate presolar material.
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Monthly Notices of the Royal Astronomical Society 514(4) 6173-6182 2022年8月1日
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2022年7月25日Abstract We performed in-situ analysis on a ~1 mm-sized Ryugu grain A0080 returned by the Hayabusa2 spacecraft to investigate the relationship of soluble organic matter (SOM) to minerals. The DESI-HRMS (desorption electrospray ionization-high resolution mass spectrometry) imaging using methanol spray identified more than 200 soluble organic compounds, which were assigned as CHN, CHO, CHO-Na (sodium adducted), and CHNO in molecular composition. Heterogeneous spatial distribution was observed for different compound classes of SOM as well as among the same alkylated homologues on the sample surface. The A0080 sample showed similar mineralogy to that of CI chondrite and contained two different lithologies, which are rich in magnetite, pyrrhotite, and dolomite (lithology 1) and poor in those minerals (lithology 2). CHN compounds were relatively concentrated in lithology 1 than in lithology 2, on the other hand, CHO, CHO-Na, and CHNO compounds were distributed in both lithologies. Such different spatial distribution of SOM is the result of interaction of the SOM with minerals, during precipitation of the SOM via fluid activity, or could be due to difference in transportation efficiencies of SOMs in aqueous fluid. However, organic-related ions measured by ToF-SIMS did not coincide with the spatial distribution revealed by DESI-HRMS imaging, indicating that the ToF-SIMS data would be mainly derived from methanol-insoluble organic matter in A0080. Alkylated homologues of CHN compounds with large C number appeared more abundant in lithology 2 than lithology 1. In contrast, fragments of the Murchison meteorite showed different features to of A0080, implying different formation or growth mechanisms for the alkylated CHN compounds by interaction with fluid and minerals on Murchison parent body and asteroid Ryugu. This difference might be mainly attributed to the carbonate grains, which would have played as a catalyst for CH2 growth of CHN compounds. Future in-situ analysis of CI chondrite will provide more reliable constraints for the history of soluble organic compounds in asteroid Ryugu.
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Icarus 381 2022年7月15日 査読有り
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Proceedings of the Japan Academy, Series B 98(6) 227-282 2022年6月10日
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Planetary and Space Science 219 105519-105519 2022年6月
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Hayabusa2 Asteroid Sample Return Mission 95-111 2022年4月 査読有り
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Science 375(6584) 1011-1016 2022年3月
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Nature Astronomy 6(2) 221-225 2022年2月
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NATURE ASTRONOMY 6(2) 214-+ 2022年2月
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Hayabusa2 Asteroid Sample Return Mission: Technological Innovation and Advances 5-23 2022年1月1日
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Proceedings of the International Astronautical Congress, IAC 2022-September 2022年
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Meteoritics & Planetary Science 2022年
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Hayabusa2 Asteroid Sample Return Mission: Technological Innovation and Advances 541-556 2022年1月1日
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Hayabusa2 Asteroid Sample Return Mission: Technological Innovation and Advances 1-3 2022年1月1日 筆頭著者責任著者
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Meteoritics & Planetary Science 2022年 査読有り
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日本地球化学会年会要旨集 69 102 2022年2021年6月のリュウグウ粒子の配分後、約１年にわたり８つの研究チーム(初期分析６チームとPhase2キュレーション２チーム)により系統的な分析が行われた。岩石・鉱物組織からみると、リュウグウは主として含水鉱物と有機物から構成され、微細な組織として複雑に共存することがわかった。また主要元素濃度、高精度酸素同位体などのバルク的分析の結果は、リュウグウ粒子は、太陽系の元素組成を代表する始原的なCIコンドライトと良い一致を示した。我々は、独自に開発した大気非曝露ナノ領域試料加工・分析システムを用い、有機物と含水鉱物の入り交ざった試料から物質科学的情報を得た。その結果、(１)含水鉱物集合体に特異的に濃集した脂肪属炭化水素に富む有機物の存在(２)太陽系で最も始原的な化学組成を持つ物質である証拠、そして(３)太陽系外縁部での形成が明らかになった。
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Hayabusa2 Asteroid Sample Return Mission 49-72 2022年 査読有り筆頭著者責任著者
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Springer Aerospace Technology 559-575 2022年
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Hayabusa2 Asteroid Sample Return Mission 415-431 2022年
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Hayabusa2 Asteroid Sample Return Mission 137-175 2022年
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Hayabusa2 Asteroid Sample Return Mission 313-340 2022年
MISC
299-
Hayabusa2024: 11th Symposium of Solar System Materials 2024年11月
主要な書籍等出版物
11-
2024年6月 (ISBN: 9788962622812)NHK出版 「はやぶさ２ 最強ミッションの真実」の韓国語訳
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2022年4月 (ISBN: 9780323997317)
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主要な講演・口頭発表等
64-
6th IEEE Electron Devices Technology and Manufacturing Conference (EDTM) 2022年3月7日 The Institute of Electrical and Electronics Engineers (IEEE) 招待有り
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72nd International Astronautical Congress 2021年10月28日 International Astronautical Federation 招待有り
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72nd International Astronautical Congress 2021年10月28日 Inetrnational Astronautical FederationIAC-21-A3.4.A.1
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18th International Planetary Probe Workshop 2021年6月17日 招待有り
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Committee on the Peaceful Uses of Outer Space (COPUOS) 2021年4月23日 招待有り
所属学協会
4共同研究・競争的資金等の研究課題
9-
日本学術振興会 科学研究費助成事業 2026年4月 - 2031年3月
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日本学術振興会 科学研究費助成事業 2022年4月 - 2025年3月
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日本学術振興会 科学研究費助成事業 基盤研究(B) 2022年4月 - 2025年3月
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日本学術振興会 科学研究費助成事業 基盤研究(B) 2018年4月 - 2022年3月
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日本学術振興会 科学研究費助成事業 基盤研究(B) 2014年4月 - 2018年3月
