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Hydrogen CyaNide (HCN) is one of the most important molecules in the origin of life, and its production processes have been widely studied. However, the production rate of HCN in the early Earth is highly uncertain. Furthermore, it is estimated to be extremely low if the early Earth atmosphere is redox-neutral (i.e., N2-CO2 dominant). We focus on a CN radicals formation process due to hypervelocity oblique impacts as a new HCN production process, because this process may be able to produce HCN efficiently within an N2-CO2 dominant atmosphere. Impact-induced CN radicals may react with water vapor in an ambient atmosphere and generate HCN. However, these chemical reactions between impact-induced CN radicals and an ambient atmosphere have not been understood well. In our previous study, we conducted laser ablation experiments using graphite targets and N2-CO2-H2O-Ar model atmospheres to simulate chemical reactions between impact-induced CN radicals and a redox-neutral atmospheres. We found that laser-induced hot CN radicals convert to HCN efficiently in an ambient atmosphere containing as much as a few hundred mbar of CO2. However, empirical scaling rules on both vapor plume size and impact velocity are necessary to estimate HCN yield on actual impacts within the early Earth atmosphere because both actual and experimental pressure-temperature conditions of CN radicals are very different. Thus, we vary laser beam diameter and intensity to investigate the effects of vapor plume size and impact velocity on the conversion ratio from hot CN radicals to HCN molecules in this study. We found that the conversion ratio increases as beam diameter increases and that it decreases as beam intensity increases (i.e., impact vapor temperature increases). However, previous experiments show that the rate of increase in CN production as a function of impact velocity is higher than the rate of decrease in conversion ratio estimated by our laser experiments. These results strongly suggest that this HCN production process works efficiently on actual asteroidal impacts., 資料番号: AA0063723025

資料番号: SA1000117000

資料番号: SA1000130000

資料番号: SA1000131000

大気球シンポジウム 平成27年度（2015年11月5-6日. 宇宙航空研究開発機構宇宙科学研究所 (JAXA)(ISAS)）, 相模原市, 神奈川県, Balloon Symposium 2015 (November 5-6, 2015. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 著者人数: 22名ほか, 資料番号: SA6000044021, レポート番号: isas15-sbs-021

第48回月・惑星シンポジウム (2015年7月29-31日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)), 相模原市, 神奈川県, 48th ISAS Lunar and Planetary Symposium (July 29-31, 2015. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 資料番号: SA6000045009

平成26年度宇宙科学に関する室内実験シンポジウム (2015年2月23日-24日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 2015 Symposium on Laboratory Experiment for Space Science (July 23-24, 2015. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 資料番号: SA6000076026

Hydrogen Cyanide (HCN) is considered as one of most important compounds for the origin of life because it is a precursor of complex organic molecules, such as amino acids and nucleic acid bases. Although a number of different mechanisms of HCN formation on the early Earth have been studied, HCN formation due to large impacts is particular important because it produces a large amount of HCN in a short period of time. We focus on the chemical interaction between impact-induced vapor clouds and a planetary atmosphere. Impact experiments by Sugita & Schultz (2000) show that a large amount of CN radicals may be produced by carbon-rich meteoritic material within a nitrogen-rich atmosphere. The produced CN radicals may react with water vapor in an ambient atmosphere and generate HCN. However, high-temperature CN may also destroy to CO and NO via chemical reactions with the ambient atmosphere. In this study, we conduct laser ablation experiments using a Gas Chromatograph Mass Spectrometer (GCMS) to examine whether impact-generated CN radicals lead to HCN formation. Graphite targets and gas mixtures of nitrogen and water vapor were used in our experiments. We found a strong correlation between the yield of HCN and the chemical composition of the model atmosphere. Although little HCN was detected in N2 atmospheres, a large amount of HCN was detected in a N2-H2O atmosphere. This result strongly suggests that impact-generated CN radicals may lead to HCN formation., 資料番号: AA0063505052

Gaseous species produced within impact-induced vapor clouds may have played an important role in surface environment of planets. However, the molecular composition of those gases is not known well. In particular, interaction between carbon compounds and silicates is poorly understood. In previous study, we confirmed experimentally that SiO2-derived oxygen reacts with carbon compounds under laboratory conditions. However, it is still not clear whether such oxidation processes occur in large planetary-scale impacts. In this study, we perform thermodynamic equilibrium calculation to assess whether the reactions between SiO2-derived oxygen and carbon compounds occur under planetary-scale impact conditions, which are characterized by various impact velocities and large scale. Our results show that large amount of SiC and/or gaseous SiO is produced at 1,000-2,000 K, where chemical reactions within planetary-scale impact-induced vapor clouds quench, regardless of impact velocity. The formation of SiC and/or gaseous SiO implies that the composition of resulting gas within planetary-scale impact-induced vapor clouds is oxidized by SiO2-derived oxygen regardless of impact velocity., 資料番号: AA0063350005

本研究では衝突クレーター形成実験を行い、放出破片の総質量を測定した。弾丸としてポリカーボネイト、標的の粒子として平均粒径200、80、40μmのガラスビーズを用いた。測定した総放出破片質量からトランジェントクレーターと総放出破片の体積関係(体積比)および掘削部分の深さ関係(深さ比)を明らかにした。体積比はトランジェントクレーターの大きさに依らず一定であるが、標的粒子の粒径に依存することがわかった。粒径200、80、40μmにおける体積比の平均値はそれぞれ0.36、0.27、0.18であった。深さ比もトランジェントクレータの大きさに依らず一定で、標的粒子の粒径に依存した。粒径200、80、40μmにおける深さ比の平均値はそれぞれ0.28、0.21、0.14であった。最後に体積比の結果を用いて、Z-modelのパラメーターであるZ値を導出した。Z値は標的粒子の粒径が小さくなるにつれて小さくなった。これらの結果より、掘削流のパターンが粒径により変わり、粒径が小さいほど掘削流は浅いことがわかった。, 資料番号: AA0046919023

There is measured the mass M(sub ex) (excavation mass) of materials excavated by impact on glass sphere targets with different grain sizes. The excavation mass M(sub ex) is shown to be nearly M(sub ex) proportional to nu (nu is projectile's impact velocity), while, it depends on the projectile mass m as followed: M(sub ex)/nu proportional to m(sup 0.6 to 0.8). The present results also show that the excavation mass depends on the target grain sizes., 資料番号: AA0047898004

Chemical reactions within impact-induced vapor clouds may have played an important role in both the evolution of atmosphere of the Earth and the origin of life. However, chemical reaction process within impact vapor clouds is not understood well yet. In particular, chemical interaction between silicates and carbon compounds has not been studied extensively. The thermal decomposition of silicates within impact vapor clouds may affect the carbon chemistry within impact vapor clouds. Laser irradiation experiments using terrestrial rocks and chondrites by Mukhin et al. (1989) show that the carbon-bearing gas produced in the laser heating experiments were composed mainly of the oxidized species, such as CO and CO2, with only small amounts of reduced species such as hydrocarbon, HCN, and CH3CHO. Mukhin et al. (1989) propose that oxygen derived from thermal decomposition of silicates may oxidize carbon. However, such an oxidation process has not been investigated in detail. Most theoretical studies on chemical reaction in impact vapor clouds neglected such an effect of oxygen released from silicates. In this study investigated quantitatively is the oxidation of carbon compounds by oxygen from SiO2 in vapor clouds using laser-pulse heating experiments., 資料番号: AA0047898009

Impact cratering experiments into soda-lime glass spheres were performed in order to investigate grain size dependence on formation process of transient craters when gravitational effects dominate over target, strength (gravity regime). Diameters and depths of transient craters for the target spheres with sizes of 50, 80, and 220 micrometer were measured. The rim diameters of the transient craters depend on the grain sizes, while the dependence in depths is small. The present data of the rim diameters of transient craters does not follow a simple power-law relation between scaled-crater radius and gravity-scaled size, which was suggested as the scaling law on crater sizes in the gravity regime (e.g., Schmidt and Housen 1987). The results may suggest that the scaling law in the gravity regime needs to take into account the effect of grain sizes., 資料番号: AA0046650069

資料番号: AA0046650052

資料番号: AA0046650019

Excavation flow in impact cratering has been usually modeled by Maxwells Z-model. However few laboratory experiments and/or numerical simulations have been done to examine whether or not the Z-model's streamlines actually express the excavation flow. A numerical simulation of impact onto granular materials by the Discrete Element Method (DEM) is suitable to trace directly the trajectories of target particles. Then a numerical code was developed to simulate impact onto granular materials. The results show that the target particles move along the Z-model's streamlines in the following cases: Z = 3 (effective origin of flow (EOF) is located at the target surface) or Z = 2.7 (EOF is located at the depth of one projectile radius). These results indicate that the Z-model is a reasonable first-order quantitative approximation for excavation flow in impact cratering process., 資料番号: AA0046650014

Fischer-Tropsch catalysis, in which CO and H2 are converted into CH4 over iron catalyst, has been suggested to play a key role in the circumplanetary nebula for the origin of CH4 in the atmosphere of Jupiter, Saturn and Titan. Experimentally investigated was the methane formation rate over iron catalyst under conditions similar to those within the circumplanetary nebula (P = 0.09-0.53 bar, T = 500-650 K, H2/CO = 1000). The results show that the methane production does not simply increase as the temperature rises predicted by the previous work, and it proceeds efficiently between T = 525 and 625 K. The results also suggest that the conversion of CO into CH4 in the circumplanetary nebula may proceed in short time and CH4-rich subnebula may be formed at early stage of its evolution. The organics, formed by the disequilibrating process from CH4, may affect the formation time of satellites and be supplied to the icy satellites., 資料番号: AA0046650005

第15回宇宙科学シンポジウム (2015年1月6日-7日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, 15th Space Science Symposium (January 6-7, 2015. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 資料番号: SA6000034314, レポート番号: S3-001

大気球シンポジウム 平成26年度（2014年11月6-7日. 宇宙航空研究開発機構宇宙科学研究所 (JAXA)(ISAS)）, 相模原市, 神奈川県, Balloon Symposium 2014 (November 6-7, 2014. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 著者人数: 16名, 資料番号: SA6000021030, レポート番号: isas14-sbs-030

第47回月・惑星シンポジウム (2014年8月4日-6日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)), 相模原市, 神奈川県, 47th ISAS Lunar and Planetary Symposium (August 4-6, 2014. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 形態: カラー図版あり, 資料番号: SA6000033029

平成25年度スペースプラズマ研究会 (2014年2月27日-28日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, Space Plasma Conference FY2013 (February 27-28, 2014. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 資料番号: SA6000077034

大気球シンポジウム 平成25年度（2013年11月14-15日. 宇宙航空研究開発機構宇宙科学研究所 (JAXA)(ISAS)）, 相模原市, 神奈川県), Balloon Symposium 2013 (November 14-15, 2013. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 著者人数: 15名, 資料番号: SA6000065030, レポート番号: isas13-sbs-030

第46回月・惑星シンポジウム (2013年8月5日-7日. 宇宙航空研究開発機構宇宙科学研究所), 相模原市, 神奈川県, 46th ISAS Lunar and Planetary Symposium (August 5-7, 2013. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 形態: カラー図版あり, 形態: CD-ROM1枚, 資料番号: SA6000015017

大気球シンポジウム 平成24年度（2012年10月16-17日. 宇宙航空研究開発機構宇宙科学研究所 (JAXA)(ISAS)）, 相模原市, 神奈川県), Balloon Symposium 2012 (October 16-17, 2012. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 資料番号: SA6000066037, レポート番号: isas12-sbs-037

第45回月・惑星シンポジウム (2012年8月1日-3日. 宇宙航空研究開発機構宇宙科学研究所), 相模原市, 神奈川県, 45th ISAS Lunar and Planetary Symposium (August 1-3, 2012. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 著者人数: 11名, 形態: カラー図版あり, 形態: CD-ROM1枚, 資料番号: SA6000014032

平成23年度スペースプラズマ研究会(2012年2月27-28日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)相模原キャンパス), 相模原市, 神奈川県, Space Plasma Conference FY2011 (February 27-28, 2012. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan, 資料番号: SA6000079028

第33回太陽系科学シンポジウム (2011年11月15-16日. 宇宙航空研究開発機構宇宙科学研究所), 相模原市, 神奈川県, 33rd Solar System Exploration Symposium (November 15-16, 2011. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 形態: カラー図版あり, 形態: CD-ROM1枚, 著者人数: 11人, Physical characteristics: Original contains color illustrations, Note: One CD-ROM, Number of authors: 11, 資料番号: AA0065389026

44th ISAS Lunar and Planetary Symposium (August 1-3, 2011. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, Laser-induced breakdown spectroscopy (LIBS) is a new in-situ elemental analysis method for satellite and planetary explorations. In this study we evaluated the accuracy of classification and elemental composition prediction of minerals with LIBS, taking future lunar landing explorations into account. We tested the classification of minerals by analyzing the LIBS spectra with principal component analysis (PCA) and prediction of elemental composition for two minerals, olivine and plagioclase, with partial least squares (PLS) regression. The results show that minerals are clearly classified and that the compositions are predicted with high accuracy; Mg# of olivine and An value of plagioclase are predicted within the error of about +/-1.4 and +/-4.4, respectively. These are the sufficient accuracy for lunar explorations. These results indicate that LIBS has a potential of being a powerful in-situ mineral analysis method for a lunar explorations., 形態: カラー図版あり, 形態: CD-ROM1枚, 著者人数: 11人, Physical characteristics: Original contains color illustrations, Note: One CD-ROM, Number of authors: 11, 資料番号: AA0065390020

44th ISAS Lunar and Planetary Symposium (August 1-3, 2011. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, A new experimental technique for gas phase chemical analysis in an open system using a two-stage light gas gun was developed. We avoid the chemical contamination from the acceleration gas with a chemically inert gas used as the wall against to the contaminant gas. As a first step, the technique was applied to shock devolatilization experiments using natural calcite samples (CaCO3) to investigate the effect of impact velocity on the impact-induced CO2 amount. We successfully obtained high-speed images, emission spectra, and the relative amount of impact-induced CO2 simultaneously. The CO2 amount at 6.7 km/s was 5.9 times than that at 4.2 km/s. This result strongly suggests that the decarbonation efficiency also depends on impact velocity. The technique developed in this study is likely to be useful for the quantitative measurements of the amount of impact-induced vapor and its chemical composition., 形態: カラー図版あり, 形態: CD-ROM1枚, Physical characteristics: Original contains color illustrations, Note: One CD-ROM, 資料番号: AA0065390018

第43回月・惑星シンポジウム (2010年8月4-6日. 宇宙航空研究開発機構宇宙科学研究所), 相模原市, 神奈川県, 43rd ISAS Lunar and Planetary Symposium (August 4-6, 2010. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, Exogenic delivery of organic molecules by cometary/asteroidal impacts is one of the most important candidates for organic supply on prebiotic Earth. Its mechanism, however, is not simple; most of organics originally contained in impacting objects are decomposed by initial impact heating and subsequent interaction of ambient atmosphere. Such decomposed organics may actually lead to synthesis of simple but chemically active organic molecules within impact vapor plumes, particularly for oblique impacts. The details of physical and chemical processes in the cloud, nevertheless, are not understood well yet. Thus, we conducted time-series spectroscopic and band-pass imaging observation of vapor clouds due to oblique impacts using a two-stage light gas gun to characterize their thermodynamic conditions. We measured velocity and blackbody temperature of these clouds as functions of time. Obtained data indicate that high-speed projectile fragments are vaporized at much higher rate than previous estimates. Such high vaporization efficiency may lead to higher rate of organic production within impact vapor plumes. Thus, such on-site organic resynthesize within impact-vapor clouds may have played a more important role in the origin of life than previously considered., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations, 資料番号: AA0065116015

第43回月・惑星シンポジウム (2010年8月4-6日. 宇宙航空研究開発機構宇宙科学研究所), 相模原市, 神奈川県, 43rd ISAS Lunar and Planetary Symposium (August 4-6, 2010. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan, Laser-induced breakdown spectroscopy (LIBS) is a very useful elemental analysis tool in planetary exploration. In this study we conducted LIBS measurements at low pressure (1x10(exp -1) Pa) to investigate the feasibility of LIBS measurement under vacuum conditions. Although the optical emission intensity decreases remarkably at low ambient pressure, our experimental results indicate that the precision of elemental abundance measurements does not decrease drastically even at 1x10(exp -1) Pa. This suggests that LIBS can be used at the surface of airless bodies, such as the Moon and asteroids., 著者人数: 11人, 形態: カラー図版あり, Number of authors: 11, Physical characteristics: Original contains color illustrations, 資料番号: AA0065116028

ispartof: Science vol:328 issue:5981 pages:975-976 status: published

平成21年度スペースプラズマ研究会(2010年3月11-12日, 宇宙航空研究開発機構宇宙科学研究本部), Space Plasma Conference(March 11-12, 2010, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan), シアン化水素(HCN)は化学進化による生命起源を考える上で最重要な分子である。室内衝突実験により、原始地球大気中での直径100m程度の小規模衝突が起こると大量のCNが生じることが示唆されている。我々は以前、原始地球の模擬大気中で黒鉛へのレーザー照射により、大気中にCNを生じさせ、周辺大気との化学反応を模擬する実験を行い、HCNの収率を調べた。その結果、中性的な大気中でも効率よくHCNが生成されることがわかった。しかし、気体中のレーザー照射が衝突現象とどう対応づけられるかは不明である。そこで本研究では２段式軽ガス銃を用いて、衝突蒸気の高速発光分光観測を行い、衝突生成蒸気とレーザー生成蒸気の熱力学状態を比較した。その結果、衝突生成CNとレーザー生成CNは共に振動非平衡状態にあること、CNの並進回転温度はC2ラジカルのそれよりも2000K程度高いこと、7km/sの衝突で生じたCN,C2の並進回転温度は900MW/cm2のレーザー照射で生じたそれと近いことがわかった。これらの結果は衝突とレーザー照射の違いによらず、類似の機構によってCNが生成されていることを示唆している。レーザー照射実験から得られた高いHCN収率は実際の衝突時にも達成される可能性が高い。原始地球への小規模衝突は生命起源に重要な役割を果たしたのかもしれない。, 形態: カラー図版あり, 形態: CD-ROM1枚, Physical characteristics: Original contains color illustrations, Note: One CD-ROM, 資料番号: AA0064740029

第32回太陽系科学シンポジウム (2010年12月20-21日. 宇宙航空研究開発機構宇宙科学研究所), 相模原市, 神奈川県, 32nd Solar System Exploration Symposium (December 20-21, 2010. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)), Sagamihara, Kanagawa Japan, 形態: カラー図版あり, 形態: CD-ROM1枚, 著者人数: 11人, Physical characteristics: Original contains color illustrations, Note: One CD-ROM, Number of authors: 11, 資料番号: AA0065421005

第10回宇宙科学シンポジウム (2010年1月7日-8日. 宇宙航空研究開発機構宇宙科学研究本部), 10th Space Science Symposium (January 7-8, 2010. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)), Sagamihara, Kanagawa Japan, 形態: カラー図版あり, 形態: CD-ROM1枚, Physical characteristics: Original contains color illustrations, Note: One CD-ROM, 資料番号: AA0064742257

第31回太陽系科学シンポジウム(2009年12月21-22日, 宇宙航空研究開発機構宇宙科学研究本部), The thirty-first Space Energy Symposium (December 21, 2009, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan), 形態: CD-ROM1枚, Note: One CD-ROM, 資料番号: AA0064738010

第31回太陽系科学シンポジウム(2009年12月21-22日, 宇宙航空研究開発機構宇宙科学研究本部), The thirty-first Space Energy Symposium (December 21, 2009, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan), 形態: カラー図版あり, 形態: CD-ROM1枚, 著者人数: 15人, Physical characteristics: Original contains color illustrations, Note: One CD-ROM, 資料番号: AA0064738009