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 学際科学研究系 助教
- 学位
- 博士(工学)(東京大学)
- J-GLOBAL ID
- 200901020915152030
- researchmap会員ID
- 5000018882
論文
33-
Journal of Evolving Space Activities 1 2023年6月12日 査読有り
-
Science 379(6634) 2023年2月24日 査読有りSamples of the carbonaceous asteroid Ryugu were brought to Earth by the Hayabusa2 spacecraft. We analyzed 17 Ryugu samples measuring 1 to 8 millimeters. Carbon dioxide–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 calcium- and aluminum-rich inclusions. The samples are rich in phyllosilicates and carbonates, which formed through aqueous alteration reactions at low temperature, high pH, and water/rock ratios of <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 that Ryugu’s parent body formed ~2 million years after the beginning of Solar System formation.
-
Science 379(6634) 2023年2月24日 査読有りThe Hayabusa2 spacecraft collected samples from the surface of the carbonaceous near-Earth asteroid (162173) Ryugu and brought them to Earth. The samples were expected to contain organic molecules, which record processes that occurred in the early Solar System. We analyzed organic molecules extracted from the Ryugu surface samples. We identified a variety of molecules containing the atoms CHNOS, formed by methylation, hydration, hydroxylation, and sulfurization reactions. Amino acids, aliphatic amines, carboxylic acids, polycyclic aromatic hydrocarbons, and nitrogen-heterocyclic compounds were detected, which had properties consistent with an abiotic origin. These compounds likely arose from an aqueous reaction on Ryugu’s parent body and are similar to the organics in Ivuna-type meteorites. These molecules can survive on the surfaces of asteroids and be transported throughout the Solar System.
-
Science 379(6634) 2023年2月24日 査読有り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 measured noble gas and nitrogen isotopes in Ryugu samples and found that they are dominated by presolar 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 different abundances among the samples. Our measurements support a close relationship between Ryugu and CI chondrites. Noble gases produced by galactic cosmic rays, indicating a ~5 million year exposure, and from implanted solar wind record the recent irradiation history of Ryugu after it migrated to its current orbit.
-
Science (New York, N.Y.) 379(6634) eabn9057 2023年2月24日 査読有りSamples of the carbonaceous asteroid (162173) Ryugu were collected and brought to Earth by the Hayabusa2 spacecraft. We investigated the macromolecular organic matter in Ryugu samples and found that it contains aromatic and aliphatic carbon, ketone, and carboxyl functional groups. The spectroscopic features of the organic matter are consistent with those in chemically primitive carbonaceous chondrite meteorites that experienced parent-body aqueous alteration (reactions with liquid water). The morphology of the organic carbon includes nanoglobules and diffuse carbon associated with phyllosilicate and carbonate minerals. Deuterium and/or nitrogen-15 enrichments indicate that the organic matter formed in a cold molecular cloud or the presolar nebula. The diversity of the organic matter indicates variable levels of aqueous alteration on Ryugu's parent body.
MISC
83-
2021年6月21日<title>Abstract</title> C-type asteroids are considered to be primitive small Solar-System bodies enriched in water and organics, providing clues for understanding the origin and evolution of the Solar System and the building blocks of life. C-type asteroid 162173 Ryugu has been characterized by remote sensing and on-asteroid measurements with Hayabusa2, but further studies are expected by direct analyses of returned samples. Here we describe the bulk sample mainly consisting of rugged and smooth particles of millimeter to submillimeter size, preserving physical and chemical properties as they were on the asteroid. The particle size distribution is found steeper than that of surface boulders11. Estimated grain densities of the samples have a peak around 1350 kg m-3, which is lower than that of meteorites suggests a high micro-porosity down to millimeter-scale, as estimated at centimeter-scale by thermal measurements. The extremely dark optical to near-infrared reflectance and the spectral profile with weak absorptions at 2.7 and 3.4 microns implying carbonaceous composition with indigenous aqueous alteration, respectively, match the global average of Ryugu, confirming the sample’s representativeness. Together with the absence of chondrule and Ca-Al-rich inclusion of larger than sub-mm, these features indicate Ryugu is most similar to CI chondrites but with darker, more porous and fragile characteristics.
-
The 52nd Lunar and Planetary Science Conference(Web) 2021年3月
-
JpGU - AGU Joint Meeting 2020(Web) 2020 2020年5月
-
Asteroid Science in the Age of Hayabusa2 and OSIRIS-REx(Web) 2019年11月
-
Asteroid Science in the Age of Hayabusa2 and OSIRIS-REx(Web) 2019年11月
-
Asteroid Science in the Age of Hayabusa2 and OSIRIS-REx(Web) 2019年11月
-
50th Lunar and Planetary Science Conference (Web) 2019年3月
-
50th Lunar and Planetary Science Conference (Web) 2019年3月
-
JpGU - AGU Joint Meeting 2019(Web) 2019 2019年
-
Hayabusa Symposium 2018 (Web) 2018年12月
-
American Geophysical Union, Fall Meeting 2018 2018年12月
-
Asia Oceania Geosciences Society 15th Annual Meeting(Web) 2018年6月
-
JpGU - AGU Joint Meeting 2018(Web) 2018 2018年5月
-
JpGU - AGU Joint Meeting 2018(Web) 2018 2018年5月
-
JpGU - AGU Joint Meeting 2018(Web) 2018 2018年5月
-
49th Lunar and Planetary Science Conference 2018(Web) 2018年3月
-
49th Lunar and Planetary Science Conference 2018(Web) 2018年3月
-
68th annual International Astronautical Congress 10 6698-6707 2017年© Copyright (2017) by International Astronautical Federation All rights reserved. An asteroid explorer Hayabusa2 will arrive at the vicinity of C-typed asteroid 162173 Ryugu in the summer 2018 and start its asteroid proximity phase which consists of various descent operations including three touchdowns (TDs) aiming to obtain surface sample of the asteroid. During descent operations, guidance, navigation and control of lateral position of the spacecraft is basically executed by the command from the ground station under round trip time up to 40 minutes. This navigation scheme is called GCP-NAV (Ground Control Points Navigation). To increase reliability in each of the critical operations adopting GCP-NAV, Real-time Integrated Operation (RIO) trainings are planned during 2017, and a Hardware-in-the-Loop Simulator (HIL) is implemented to emulate the actual operational environment with the spacecraft behavior. This paper first presents the brief explanation of touchdown operation, then system configuration and major functions of HIL are described which enables the ground operator to perform closedloop descending operation training using unique GCP-NAV scheme. The validation results of the simulator obtained from actual operation training session are also reported. Finally, detail schedule of RIO training campaign is introduced.
-
The 8th Symposium on Polar Science 8th 2017年
-
日本惑星科学会誌遊星人 26(4) 139-143 2017年<p>「はやぶさ2」は，C 型小惑星リュウグウ（Ryugu）にランデブーし，母船からのリモートセンシング観測及び小型着陸機によるその場観測を行うとともに，最大3 回の表面物質サンプリングを行うこととなっている．サンプリング地点には，リュウグウそのものや母天体，さらには太陽系形成時の惑星集積過程と物質進化について，最大の情報を得られる場所を選定する必要があるが，選定のために必要となる情報はランデブー後取得されるリモートセンシング観測の結果を待たねばならない．そのため，限られた時間の中で小惑星の特徴を把握し，安全性と科学価値の評価（Landing Site Selection, LSS）を行う手順を確立しておくことは必須である．本稿では，はやぶさ2 プロジェクトが来年に迫ったLSS 本番に向けて実施したLSS 訓練について概説する．</p>
講演・口頭発表等
28所属学協会
1共同研究・競争的資金等の研究課題
7-
日本学術振興会 科学研究費助成事業 2022年4月 - 2025年3月
-
日本学術振興会 科学研究費助成事業 基盤研究(C) 2018年4月 - 2021年3月
-
日本学術振興会 科学研究費助成事業 基盤研究(C) 2014年4月 - 2017年3月
-
日本学術振興会 科学研究費助成事業 基盤研究(C) 2010年 - 2012年
-
日本学術振興会 科学研究費助成事業 基盤研究(B) 2004年 - 2005年
