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 太陽系科学研究系 准教授東京大学大学院 理学系研究科化学専攻 准教授
- 学位
- 博士(理学)(1996年3月 東京大学)
- 研究者番号
- 30321566
- J-GLOBAL ID
- 201501026547105146
- researchmap会員ID
- B000243484
- 外部リンク
専門は惑星科学、惑星物理学、惑星物質・物性科学、惑星探査科学。特に熱赤外カメラを用いた史上初の小惑星探査により、惑星探査に「熱撮像」の手法を世界で初めて導入に成功し、さらに「太陽系物性科学」の分野を創設。観測機器の開発による惑星探査でのその場観測とサンプルリターンによる帰還試料分析を主な研究手法とする。
主要な開発機器は、蛍光X線分光計、熱赤外カメラ、多波長熱赤外カメラである。また開発中のものはマルチターン飛行時間型質量分析計等である。地上分析においてはハイパースペクトル顕微鏡(フランスIAFとの共同)やロックインサーモグラフィ法による熱拡散率顕微鏡(石崎拓也氏と共同)による帰還試料の分析の他、将来の資料熱物性分析のための多色熱赤外顕微鏡の開発を推進中である。
◆国内外の惑星探査計画(観測機器担当)
・月探査「Lunar-A」 光学カメラLIC(Co-I)1993-2005
・火星探査「のぞみ」 HFレーダ高度計PWS/ALT(Co-I)1994-2003、可視カメラMIC(Co-I)1995-2003
・小惑星探査「はやぶさ」 蛍光エックス線分光計XRS担当(PI)1995-2010
・月周回探査「かぐや(SELENE)」 蛍光X線分光計XRS担当(PI)1998-2009
・小惑星探査「はやぶさ2」 中間赤外カメラTIR担当(PI)2010-present.、
・小惑星探査「はやぶさ2」 小型ランダーMASCOT担当(JAXAリエゾン)2010-2019
・小惑星探査「はやぶさ2」 デジタルエレキDE担当(PI)2010-present
・小惑星探査「はやぶさ2」 ハイパースペクトル顕微鏡MicrOmega担当(Co-PI)2019-present
・二重小惑星探査計画Hera 熱赤外カメラTIRI担当(PI)2020-present
・二重小惑星探査計画Hera Hera Investigation Team メンバ(招聘)2020-present
・地球近傍遭遇小惑星探査計画RAMSES 熱赤外カメラTIRI担当(PI)2025-present
◆帰還サンプルの分析(地上分析)
・JAXAキュレーションセンター(地球外物質研究グループ所属)2009-present
・ハイパースペクトル顕微鏡MicrOmega-CF(Co-PI)
・熱赤外顕微鏡(PI)
◆海外ミッション参画
・SMART-1 D-CIXS(Co-I)2000-2005
・Chandrayaan-1 C1XS(Co-I)2006-2009
・BepiColombo MIXS(Co-I)2003-present、SIXS (Co-I)2003-present
・Hera (-JP) Proejct Manager & TIRI(PI)2020-present、Investigation Team 2020-present
◆WG参画
・ESA MarcoPolo(=Hayabusa-MkII)においてX線分光、熱積外カメラ、着陸機
・月着陸機SELENE-B、SELENE-II
・月着陸SLIM(科学システム検討担当)
・火星探査MELOS(科学システム検討担当(固体惑星)、着陸探査)
・OKEANOS (科学システム検討担当、質量分析計HRMSの開発)
・月縦孔探査Uzume(科学システム検討担当、熱赤外カメラの開発)
・次世代小天体サンプルリターン理学WG(代表)
研究キーワード
32経歴
7-
2011年4月 - 現在
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2006年9月 - 現在
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2008年4月 - 2013年3月
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2003年10月 - 2006年8月
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1999年2月 - 2003年9月
学歴
4-
1993年 - 1996年
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1991年 - 1993年
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1989年 - 1991年
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1987年 - 1989年
委員歴
3-
2012年8月 - 2013年8月
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2010年8月 - 2012年8月
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2009年8月 - 2010年8月
受賞
24-
2020年12月
論文
255-
Meteoritics & Planetary Science 2024年11月25日Abstract Nucleosynthetic isotope variations are powerful tracers to determine genetic relationships between meteorites and planetary bodies. They can help to link material collected by space missions to known meteorite groups. The Hayabusa 2 mission returned samples from the Cb‐type asteroid (162173) Ryugu. The mineralogical, chemical, and isotopic characteristics of these samples show strong similarities to carbonaceous chondrites and in particular CI chondrites. The nucleosynthetic isotope compositions of Ryugu overlap with CI chondrites for several elements (e.g., Cr, Ti, Fe, and Zn). In contrast to these isotopes, which are of predominately supernovae origin, s‐process variations in Mo isotope data are similar to those of carbonaceous chondrites, but even more s‐process depleted. To further constrain the origin of this depletion and test whether this signature is also present for other s‐process elements, we report Zr isotope compositions for three bulk Ryugu samples (A0106, A0106‐A0107, C0108) collected from the Hayabusa 2 mission. The data are complemented with that of terrestrial rock reference materials, eucrites, and carbonaceous chondrites. The Ryugu samples are characterized by distinct 96Zr enrichment relative to Earth, indicative of a s‐process depletion. Such depletion is also observed for carbonaceous chondrites and eucrites, in line with previous Zr isotope work, but it is more extreme in Ryugu, as observed for Mo isotopes. Since s‐process Zr and Mo are coupled in mainstream SiC grains, these distinct s‐process variations might be due to SiC grain depletion in the analyzed materials, potentially caused by incomplete sample digestion, because the Ryugu samples were dissolved on a hotplate only to avoid high blank levels for other elements (e.g., Cr). However, local depletion of SiC grains cannot be excluded. An alternative, equally possible scenario is that aqueous alteration redistributed anomalous, s‐process‐depleted, Zr on a local scale, for example, into Ca‐phosphates or phyllosilicates.
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Science Advances 10(39) 2024年9月27日The isotopic compositions of samples returned from Cb-type asteroid Ryugu and Ivuna-type (CI) chondrites are distinct from other carbonaceous chondrites, which has led to the suggestion that Ryugu/CI chondrites formed in a different region of the accretion disk, possibly around the orbits of Uranus and Neptune. We show that, like for Fe, Ryugu and CI chondrites also have indistinguishable Ni isotope anomalies, which differ from those of other carbonaceous chondrites. We propose that this unique Fe and Ni isotopic composition reflects different accretion efficiencies of small FeNi metal grains among the carbonaceous chondrite parent bodies. The CI chondrites incorporated these grains more efficiently, possibly because they formed at the end of the disk’s lifetime, when planetesimal formation was also triggered by photoevaporation of the disk. Isotopic variations among carbonaceous chondrites may thus reflect fractionation of distinct dust components from a common reservoir, implying CI chondrites/Ryugu may have formed in the same region of the accretion disk as other carbonaceous chondrites.
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Nature Astronomy 2024年9月25日
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Nature Communications 15(1) 2024年9月5日Abstract Returned samples from the carbonaceous asteroid (162173) Ryugu provide pristine information on the original aqueous alteration history of the Solar System. Secondary precipitates, such as carbonates and phyllosilicates, reveal elemental partitioning of the major component ions linked to the primordial brine composition of the asteroid. Here, we report on the elemental partitioning and Mg isotopic composition (25Mg/24Mg) of breunnerite [(Mg, Fe, Mn)CO3] from the Ryugu C0002 sample and the A0106 and C0107 aggregates by sequential leaching extraction of salts, exchangeable ions, carbonates, and silicates. Breunnerite was the sample most enriched in light Mg isotopes, and the 25Mg/24Mg value of the fluid had shifted lower by ~0.38‰ than the initial value (set to 0‰) before dolomite precipitation. As a simple model, the Mg2+ first precipitated in phyllosilicates, followed by dolomite precipitation, at which time ~76−87% of Mg2+ had been removed from the primordial brine. A minor amount of phyllosilicate precipitation continued after dolomite precipitation. The element composition profiles of the latest solution that interacted with the cation exchange pool of Ryugu were predominantly Na-rich. Na+ acts as a bulk electrolyte and contributes to the stabilization of the negative surface charge of phyllosilicates and organic matter on Ryugu.
MISC
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Europlanet Science Congress 2020 EPSC2020-12 2024年5月2日 招待有り筆頭著者責任著者<p>Thermal imaging, or thermography, has revealed the surface physical state of the C-type near-Earth asteroid 162173 Ryugu (Okada et al., 2020). The asteroid is the target body of JAXA Hayabsua2 asteroid sample return mission, and it has been characterized through remote sensing and surface experiments, and will be deeply and accurately investigated by analysis of returned sample. Thermal observations are among such multi-scale observations, providing a new insight into understanding planetary evolution process.</p> <p>Thermal infrared imager TIR (Okada et al., 2017; 2020) was used to take one-rotation global thermal images of Ryugu at every 6° step, from the home position (20 km altitude) or from the Mid-Altitude (5 km altitude). There were two big surprises contrary to the predictions before arrival at Ryugu: i) flat diurnal temperature profiles compared to the case of non-rough surface, and ii) non-cold spots identified for most of boulders. The flat diurnal temperature profiles and its maximum temperature in a day indicate that Ryugu must have very rough surfaces made of highly porous materials, derived from the thermal inertia of 300 ± 100 J K<sup>-1</sup>s<sup>-0.5</sup>m<sup>-2</sup> (hereafter, tiu). Non-cold boulders indicate that boulders are less consolidated or compacted than typical carbonaceous chondrite meteorites, and shows the same thermophysical properties as the surroundings. TIR was also used to take close-up thermal images during the descent operations, and to have proven that the surface of asteroid is covered with fragments of porous rocks, larger than several centimeters in diameter. The typical size of fragments larger than thermal skin depth (~35 mm) results in similar thermal properties between the boulders and their surroundings. We also consider the surface roughness effect (Shimaki et al., 2020) to obtain the maps of thermal inertia ( 225 ± 45 tiu) and the roughness (0.41 ± 0.05) at the same time, corresponding to very rough surfaces made of highly-porous materials. This thermal inertia is basically consistent with the value (282 +93/-35 tiu) by in situ measurement using a thermal radiometer MARA on MASCOT lander (Grott et al., 2019). Furthermore, in the close-up thermal images, there were found boulders colder by 20 °C or more, indicating the thermal inertia of typical carbonaceous chondrite meteorites.</p> <p>Considering these results, we proposed a formation scenario of Ryugu: fluffy cosmic dusts gathered to form porous planetesimals, and then much larger sized but still porous bodies. A low degree of consolidation and alteration has occurred at most of the body, while a higher degree of consolidation or alteration proceeded at the deep interior. Huge meteoritic impacts destroyed and fragmented the bodies, and part of those fragments were re-accreted to form the next generation, rubble-pile bodies (asteroids). Boulders found on Ryugu might have originated from the deep interior of parent bodies, so that most of them are very porous and less consolidated but some of them are relatively dense materials similar to carbonaceous chondrites, which might have originated from the interior. Due to YORP effect, the rotation rate decreased to current one, and the current shape of a spinning top-shape were formed. Analysis of returned sample will make progress in our knowledge of the planetary formation process.</p>
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Icarus 400 2023年8月This paper summarizes the evidence for the optical effects of space weathering, as well as the properties of the surface that control optical changes, on asteroid (101955) Bennu. First, we set the stage by briefly reviewing what was known about space weathering of low-albedo materials from telescopic surveys, laboratory simulations, and sample return analysis. We then look at the evidence for the nature of space weathering on Bennu from recent spacecraft imaging and spectroscopy observations, including the visible to near-infrared and thermal infrared wavelengths, followed by other measurements such as normal albedo measurements from LIDAR scans. We synthesize these different lines of evidence in an effort to describe a general model of space weathering processes and resulting color effects on dark C-complex asteroids, with hypotheses that can be tested by analyzing samples returned by the mission. A working hypothesis that synthesizes findings thus far is that the optical effects of maturation in the space environment depend on the level of hydration of the silicate/phyllosilicate substrate. Subsequent variations in color depend on surface processes and exposure age. On strongly hydrated Bennu, in color imaging data, very young craters are darker and redder than their surroundings (more positive spectral slope in the wavelength range 0.4–0.7μm) as a result of their smaller particle sizes and/or fresh exposures of organics by impacts. Solar wind, dehydration, or migration of fines may cause intermediate-age surfaces to appear bluer than the very young craters. Exposed surfaces evolve toward Bennu's moderately blue global average spectral slope. However, in spectroscopic and LIDAR data, the equator, the oldest surface on Bennu, is darker and redder (wavelength range 0.55–2.0μm) than average and has shallower absorption bands, possibly due to dehydration and/or nanophase and/or microphase opaque production. Bennu is a rubble pile with an active surface, making age relationships, which are critical for determining space weathering signals, difficult to locate and quantify. Hence, the full story ultimately awaits analyses of the Bennu samples that will soon be delivered to Earth.
講演・口頭発表等
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精密工学会大会学術講演会講演論文集 2014年 公益社団法人 精密工学会次世代月惑星科学探査のための岩石切断法として,ワイヤソー切断法を検討しているが,真空中ではダイヤモンド砥粒を固定するニッケルが工作物である岩石に付着する問題が明らかになっている.本報では,摩擦試験を行うことで付着原因を推定した.大気中ではニッケル表面に酸化膜が形成されるが,真空中では形成されない.純ニッケルの方がその酸化膜よりも軟らかく,靱性が高いため,真空中では加工が進まなかったと考えられる.
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日本地球化学会年会講演要旨集 2014年 一般社団法人日本地球化学会はやぶさ試料中にはカテゴリ3とよばれる有機物を主としたものが報告されており、それらが地球外有機物かあるいは地球の汚染物質か未だに解明されていない。そこでカテゴリ3試料中の水素、炭素と窒素の同位体組成をNanoSIMSを用いた同位体イメージングにより測定した。それらの同位体組成は測定した三つの試料において地球の値を示し、同位体組成からの情報からだけでは地球外有機物であると結論づけられなかった。今後は同位体だけではなく、TEMやXANES、ラマン分光などを用いた測定をすることで、カテゴリ3試料の起源を解明する事が期待される。
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日本惑星科学会秋期講演会予稿集 2013年11月20日 日本惑星科学会
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Proceedings of International Astrobiology Workshop 2013 2013年11月
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METEORITICS & PLANETARY SCIENCE 2013年7月 WILEY-BLACKWELL
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Abstracts of 10th Annual Meeting of Asia Oceania Geosciences Society (AOGS 2013) 2013年6月
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宇宙航空研究開発機構特別資料 JAXA-SP- 2013年3月29日
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日本惑星科学会誌遊星人 2013年 日本惑星科学会地球外物質の採取・記載・保管および配布の目的で発足したJAXAキュレーションセンターでは,現在は小惑星イトカワにタッチダウンした探査機「はやぶさ」の試料を取り扱っている.「はやぶさ」から分離して地球帰還した再突入カプセルを受け入れ,その内部の試料コンテナを取り出してクリーンチェンバー内に導入し,開封を行った.試料コンテナ内の残留ガスから地球外起源の希ガスは検出できなかったが,キャッチャー内部からは主にケイ酸塩鉱物から成る微粒子を回収した.初期記載の結果,それらの鉱物比・鉱物組成がLL4-6コンドライト隕石に近いことが分かり,イトカワ試料と確認された.現在までに400個以上の粒子の回収・初期記載を行い,そのうち8割がイトカワ粒子だった.キュレーションセンターではこの試料を初期分析チーム,NASA,国際公募研究に対して配布し,多様な科学成果が挙がっている.
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日本惑星科学会誌 遊・星・人 2013年 日本惑星科学会地球外物質の採取・記載・保管および配布の目的で発足したJAXAキュレーションセンターでは,現在は小惑星イトカワにタッチダウンした探査機「はやぶさ」の試料を取り扱っている.「はやぶさ」から分離して地球帰還した再突入カプセルを受け入れ,その内部の試料コンテナを取り出してクリーンチェンバー内に導入し,開封を行った.試料コンテナ内の残留ガスから地球外起源の希ガスは検出できなかったが,キャッチャー内部からは主にケイ酸塩鉱物から成る微粒子を回収した.初期記載の結果,それらの鉱物比・鉱物組成がLL4-6コンドライト隕石に近いことが分かり,イトカワ試料と確認された.現在までに400個以上の粒子の回収・初期記載を行い,そのうち8割がイトカワ粒子だった.キュレーションセンターではこの試料を初期分析チーム,NASA,国際公募研究に対して配布し,多様な科学成果が挙がっている.
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INFRARED REMOTE SENSING AND INSTRUMENTATION XXI 2013年 SPIE-INT SOC OPTICAL ENGINEERINGThermal infrared imager system is developed for HAYABUSA2, which is planned to be launched in 2014 and aims at sample-return from a C class near-Earth asteroid 1999JU3 considered to contain organic or hydrated materials. The system consists of a thermal-infrared imager (TIR) and a digital electronics, which is used not only for the scientific investigation of physical properties of the asteroid surface, but also for the assessment of landing site selection and safe descent operation onto the asteroid surface with in situ measurement.Since round trip communication time between the asteroid and the Earth is more than thirty minutes, onboard automatic data processing function and high speed data recording capability are provided to exploit the limited downlink capacity which is up to 32kbps.TIR adopts an uncooled bolometer with 320 x 240 effective pixels. Image operations as multiple images summation, dark image subtraction, and the compensation of dead pixels are processed onboard. A processing module is connected to sensor interfaces through SpaceWire in order to provide deterministic processing time. Data compression is also provided to reduce restriction on storage capacity and operation time, which provides the equivalent compression ratio as JPEG2000 in 1/30 processing time in average. A high speed data recorder is also connected through SpaceWire in 50Mbps in order to record TIR data in parallel with other sensor data.The modularity of SpaceWire enables to use as built devices for TIR and inherits the same design as the long-wavelength infrared imager developed for the Venus climate orbiter Akatsuki.
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Proceedings of the International Astronautical Congress, IAC 2013年The Memorandum of Understanding signed between the Japanese Aerospace Exploration Agency (JAXA) and the German Aerospace Centre (DLR) during the 63rd International Astronautical Congress (IAC) in Naples, paves the way for the Mobile Asteroid Surface Scout (MASCOT) participation in JAXAs Hayabusa-II mission. Like its famous predecessor, Hayabusa-II is foreseen to study and return samples from a Near-Earth Asteroid. In contrast to the previous mission, Hayabusa-II will also include a small lander package being developed by DLR and the Centre National d'Etudes Spatiales (CNES): the aforementioned MASCOT. Scheduled for a launch in 2014, Hayabusas-II journey will take 4 years until it will arrive at 1999JU3, a C-type asteroid. Following the initial remote sensing operations, MASCOT will be released to the surface and perform its science operations at its first location. Once this is complete, MASCOT will be able to 'hop' from one measurement site to the next. The payload suite will comprise a near-infrared microscope (MicrOmega, IAS Paris), a camera (CAM, DLR Berlin), a radiometer (MARA, DLR Berlin) and a magnetometer (MAG, TU Braunschweig). Realizing MASCOTs mission is difficult due to the strict mission requirements, the harsh landing environment and a short development time for a piggyback deep space mission. Aiming for high performance and reliability requires creative design solutions and novel developments in order to meet all challenges and to stay inside the mass limit of 11 kg. The status of MASCOT up to end of Phase B was presented at the 63rd IAC. With a flight model delivery scheduled for March 2014, the mission is now in the final stage of development and testing. The results of these tests have shown the strict limits of the structure and thermal design, and highlighted the risk in such a short project development. Lessons have also been learned regarding margin policy for such small spacecraft. Despite these challenges, the project is on-track, with all delivery milestones expected to be met. These last few months will serve to verify all of the design assumptions, before the launch in late 2014.
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METEORITICS & PLANETARY SCIENCE 2012年7月 WILEY-BLACKWELL
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METEORITICS & PLANETARY SCIENCE 2012年7月 WILEY-BLACKWELL
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METEORITICS & PLANETARY SCIENCE 2012年7月 WILEY-BLACKWELL
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METEORITICS & PLANETARY SCIENCE 2012年7月 WILEY-BLACKWELL
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Proceedings of Asteroids, Comets, Meteors 2012 2012年5月
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分析化学 = Japan analyst 2012年4月5日 公益社団法人 日本分析化学会宇宙航空研究開発機構(JAXA)はやぶさ探査機が,近地球型小惑星のイトカワから持ち帰った微小試料についてラマン分光分析を行い,樹脂に包埋された直径30から150 μmの試料中の鉱物の同定を試みた.ラマン分光分析によって同定されたケイ酸塩鉱物及び酸化鉱物は,カンラン石,輝石,斜長石,クロム鉄鉱である.それらは,エネルギー分散型スペクトロメーター付走査電子顕微鏡観察で同じ研磨断面試料から同定されたケイ酸塩鉱物・酸化鉱物と一致した.また,斜長石が衝撃により固相状態で非晶質化したマスケリナイトはラマン分光法で同定可能であるが,完全にマスケリナイト化した斜長石は見いだされなかった.このことは,本研究で分析したイトカワ微小試料が経験した衝撃ステージは,S4には到達していないことを示唆しており,他の初期分析の結果と整合的である.
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Proceedings of the International Astronautical Congress, IAC 2012年The JAXA Hayabusa-II mission is the follow-up to the original Hayabusa mission launched in 2003 \ which succeeded in returning the first dust particles from a near-Earth asteroid to Earth. JAXA intends to launch Hayabusa-II in 2014 for similar measurements of the asteroid 1999 JU3, a C-type asteroid, and invited the German Aerospace Centre (DLR) to contribute a small lander package to the mission. Based on this invitation, DLR is developing the Mobile Asteroid Surface Scout (MASCOT) to complement the main spacecraft's scientific objectives, with the Centre National d'Etudes Spatiales (CNES) providing payload and subsystem support. MASCOT will provide in-situ surface science and allow investigation of up to three sites on the asteroid surface. A short on-asteroid lifetime of two complete asteroid rotations (-16 hours) will provide measurements under different illuminations and thermal conditions, with Hayabusa-II being used to transmit all of the scientific data back to Earth. The harsh landing environment and strict mission requirements lead to some difficult design challenges. An innovative "hopping" mechanism will allow MASCOT to leap across the asteroid surface in bounds of up to 220m, albeit robustness of this concept must first be proven in a comprehensive suite of simulations and tests. Mass, limited to 10 kg, is critical: savings via the use of a carbon-fibre main structure and simplified subsystems allows the carriage of four scientific payloads, namely a multispectral wide angle camera, a radiometer, a magnetometer and an IR microscope. Thermal control is a challenge given the contrasting requirements of deep-space cruise and on- surface operation. Available energy also puts a strict limit on operations and restricts the lifetime of the mission. Copyright © (2012) by the International Astronautical Federation.
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精密工学会大会学術講演会講演論文集 2012年 公益社団法人 精密工学会宇宙環境で使用可能な岩石加工法として,ワイヤソー切断加工を検討している.本報では,真空中の加工特性として,加工速度,研削比,加工中の真空度の変化を求めた結果について述べる.ニッケル付着により加工速度が低下する.ニッケル上でダイヤモンド砥粒がしゅう動するが,切り込み荷重が小さいため摩耗量は大きくなかった.
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精密工学会大会学術講演会講演論文集 2012年 公益社団法人 精密工学会宇宙環境で使用可能な岩石加工法として,ワイヤソー切断加工を検討している.本報では,真空中の加工特性として,切断時の動力を測定した結果について述べる.ワイヤ走行速度が0.3~1m/sの範囲で主分力および切り込み荷重を同時に測定した.主分力は大気中,真空中ともにほぼ一定であった.したがって,動力はワイヤ走行速度に比例した.また,動力は真空中の方が大きかった.
所属学協会
5共同研究・競争的資金等の研究課題
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日本学術振興会 科学研究費助成事業 新学術領域研究(研究領域提案型) 2017年6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 - 2019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(C) 2010年 - 2012年
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日本学術振興会 科学研究費助成事業 若手研究(A) 2005年 - 2007年
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日本学術振興会 科学研究費助成事業 基盤研究(C) 2002年 - 2003年
● 専任大学名
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専任大学名東京大学(University of Tokyo)
● 所属する所内委員会
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所内委員会名放射線安全委員会