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KUROSAWA KosukeGraduate School of Human Development and Environment / Department of Human Environmental ScienceAssociate Professor
Researcher basic information
■ Research Keyword- Planetary Science
- アストロバイオロジー
- Impact phenomena
- Environmental Science
- Emission spectroscopy
- Mass spectrometry
- High-speed imaging
- Two-stage light gas gun
- Chemical reactions
- Phase change
- Natural sciences / Space and planetary science
- Natural sciences / Solid earth science / Impact physics
- Apr. 2025 - Present, 生命の起源・アストロバイオロジー学会, 学会誌編集委員
- Jan. 2025 - Present, 日本惑星科学会, 広報専門委員長
- Jan. 2025 - Present, 日本惑星科学会, 運営委員
- Jan. 2025 - Present, 日本惑星科学会, 将来計画専門委員会
- May 2019 - Present, 日本惑星科学会, 広報専門委員
- Jan. 2019 - Present, 日本惑星科学会, 情報化専門委員会
- Jan. 2015 - Present, 日本惑星科学会, 学会誌編集委員
- Sep. 2024 - Mar. 2025, 生命の起原および進化学会, 選挙管理委員
- Sep. 2022 - Mar. 2025, 生命の起原および進化学会, 学会誌編集委員
- Sep. 2020 - Jan. 2022, 生命の起原および進化学会, 運営委員
- Apr. 2018 - Mar. 2020, 日本惑星科学会, 学会賞選考委員
- Apr. 2015 - Mar. 2016, 日本惑星科学会 衝突研究会, 世話人代表
Research activity information
■ Award- Oct. 2019 JAXA, Head director award, 火星衛星及びそこで採取するサンプルの潜在的な微生物汚染確率評価
- Sep. 2016 日本惑星科学会, 2015年度最優秀研究者賞
- Extraterrestrial minerals on the surface of airless Solar System bodies undergo gradual alteration processes known as space weathering over long periods of time. The signatures of space weathering help us understand the phenomena occurring in the Solar System. However, meteorites rarely retain the signatures, making it impossible to study the space weathering processes precisely. Here, we examine samples retrieved from the asteroid Ryugu by the Hayabusa2 spacecraft and discover the presence of nonmagnetic framboids through electron holography measurements that can visualize magnetic flux. Magnetite particles, which normally provide a record of the nebular magnetic field, have lost their magnetic properties by reduction via a high-velocity (>5 km s–1) impact of a micrometeoroid with a diameter ranging from 2 to 20 μm after destruction of the parent body of Ryugu. Around these particles, thousands of metallic-iron nanoparticles with a vortex magnetic domain structure, which could have recorded a magnetic field in the impact event, are found. Through measuring the remanent magnetization of the iron nanoparticles, future studies are expected to elucidate the nature of the nebular/interplanetary magnetic fields after the termination of aqueous alteration in an asteroid.Dec. 2024, Nature Communications, 15(1) (1), English[Refereed]Scientific journal
- Abstract Feather features (FFs) in quartz consist of a planar fracture (PF) and associated fine lamellae (FF lamellae; FFL) and have been observed in various natural impact structures. However, the mechanisms and conditions of FF formation are poorly understood. We conducted shock recovery experiments on granite using decaying compressive pulses to investigate the formation conditions of FFs. We characterized the recovered samples using an optical microscope equipped with a universal stage, a scanning electron microscope combined with an electron back‐scattered diffraction detector, and a transmission electron microscope. We found that FFs are formed over a wide range of peak pressures (2–18 GPa) and that FFs can be divided into at least three types (I–III) based on the crystallographic orientation of the PFs and FFL, the angle between the orientation of the FFL and the propagation direction of the compression wave, and the presence/absence of amorphous silica in the FFL. The peak pressures that produce type I–III FFs are estimated to be <12, 12–14, and >16 GPa, respectively. We propose that FFs can be used as a shock barometer for quartz‐bearing rocks.American Geophysical Union (AGU), Oct. 2024, Journal of Geophysical Research: Planets, 129(11) (11), English[Refereed]Scientific journal
- Abstract Shock recovery experiments were performed using a two-stage light gas gun to clarify the progressive deformation microstructures of calcite at the submicron scale concerning pressure. Decaying compression pulses were produced using a projectile that was smaller than the natural marble target. In two experiments, natural marble samples were shocked to 13 and 18 GPa at the epicenters of the targets. Calcite grains shocked in the pressure range of 1.1–18 GPa were examined using polarized light microscopy and (scanning) transmission electron microscopy. The density of free dislocations in the grains shocked at 1.1–2.2 GPa [108–9 (cm-2)] is comparable to that of unshocked Carrara calcite grains. Subparallel bands of entangled dislocations less than 1 µm are formed at 4.2 GPa, and strongly entangled dislocations spread throughout the focused ion beam (FIB) sections at 7.3–18 GPa pressures. Dislocations selectively nucleate and entangle near the slip planes at pressures above ~3 GPa, corresponding to the transition from sharp extinction to undulatory extinction, according to the microstructural evolution with shock pressure. Above approximately 6 GPa, the dislocations nucleated homogeneously throughout the calcite crystals. The dislocation microstructure in a calcite grain collected from the asteroid Ryugu particle is similar to that of the experimentally shocked calcite at 4.2 GPa. The estimated pressure of 2–3 GPa, determined through fault mechanics analyses and the presence of dense sulfide minerals in the Ryugu particles, is in line with this pressure.Mineralogical Society of America, Sep. 2024, American Mineralogist, English[Refereed]Scientific journal
- A leading candidate for the heating source of chondrules and igneous rims is shock waves. This mechanism generates high relative velocities between chondrules and dust particles. We have investigated the possibility of the chondrule destruction in collisions with dust particles behind a shock wave using a semianalytical treatment. We find that the chondrules are destroyed during melting in collisions. We derive the conditions for the destruction of chondrules and show that the typical size of the observed chondrules satisfies the condition. We suggest that the chondrule formation and rim accretion are different events if they are heated by shock waves.May 2024, Astrophysical Journal, 966(2) (2), English[Refereed]Scientific journal
- Abstract Knowledge of the shock remanent magnetization (SRM) property is crucial for interpreting the spatial change in a magnetic anomaly observed over an impact crater. This study conducted two series of impact‐induced SRM acquisition experiments by varying the applied field intensity (0–400 μT) and impact conditions. Systematic remanence measurements of cube‐shaped subsamples cut from shocked basalt containing single‐domain titanomagnetite were conducted to investigate the effects of changes in pressure and temperature on the SRM acquisition. The peak pressure and temperature distributions in the shocked samples were estimated using shock‐physics modeling. SRM intensity was proportional to the applied field intensity of up to 400 μT. SRM intensity data for peak pressure and temperature of up to 8.0 GPa and 530 K, respectively, clearly show that it increases with increasing pressure and decreases with increasing temperature. The SRM has unblocking temperature components up to a Curie temperature of 510 K, and it easily demagnetizes with alternating field demagnetization. The observed SRM properties can be explained by the pressure‐induced microcoercivity reduction and temperature‐induced modification of the blocking curve. Although the remanence acquisition efficiency of the SRM is significantly lower than that of the thermoremanent magnetization (TRM), the magnetic anomaly originating from the SRM distribution in a broader region may show a contribution comparable to that of the impact‐induced TRM distribution in a narrow region.American Geophysical Union (AGU), Mar. 2024, Journal of Geophysical Research: Planets, 129(3) (3)[Refereed]Scientific journal
- American Geophysical Union (AGU), May 2023, Journal of Geophysical Research: Planets, 128(6) (6)[Refereed]Scientific journal
- Abstract Micrometeorites, a possible major source of Earth’s water, are thought to form from explosive dispersal of hydrated chondritic materials during impact events on their parental asteroids. However, this provenance and formation mechanism have yet to be directly confirmed using asteroid returned samples. Here, we report evidence of mild shock metamorphism in the surface particles of asteroid Ryugu based on electron microscopy. All particles are dominated by phyllosilicates but lack dehydration textures, which are indicative of shock-heating temperatures below ~500 °C. Microfault-like textures associated with extensively shock-deformed framboidal magnetites and a high-pressure polymorph of Fe–Cr–sulfide have been identified. These findings indicate that the average peak pressure was ~2 GPa. The vast majority of ejecta formed during impact on Ryugu-like asteroids would be hydrated materials, larger than a millimetre, originating far from the impact point. These characteristics are inconsistent with current micrometeorite production models, and consequently, a new formation mechanism is required.Springer Science and Business Media LLC, Apr. 2023, Nature Astronomy[Refereed]Scientific journal
- Abstract Basaltic rocks occur widely on the terrestrial planets and differentiated asteroids, including the asteroid 4 Vesta. We conducted a shock recovery experiment with decaying compressive pulses on a terrestrial basalt at the Chiba Institute of Technology, Japan. The sample recorded a range of pressures, and shock physics modeling was conducted to add a pressure scale to the observed shock features. The shocked sample was examined by optical and electron microscopy, electron back‐scattered diffractometry, and Raman spectroscopy. We found that localized melting occurs at a lower pressure (∼10 GPa) than previously thought (>20 GPa). The shocked basalt near the epicenter represents “shock degree C” of a recently proposed classification scheme for basaltic eucrites and, as such, our results provide a pressure scale for the classification scheme. Finally, we estimated the total fraction of the basaltic eucrites classified as shock degree C to be ∼15% by assuming the impact velocity distribution onto Vesta.Corresponding, American Geophysical Union (AGU), Jan. 2023, Geophysical Research Letters, 50(1) (1), English[Refereed]Scientific journal
- 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.American Association for the Advancement of Science (AAAS), Sep. 2022, Science, 379(6634) (6634)[Refereed]Scientific journal
- Abstract Experiments on crater formation in the strength regime were conducted using projectiles of various shapes with an aspect ratio of ~ 1, including both solid and hollow interiors. The surface diameter, inner (pit) diameter, and depth of the craters on basalt and porous gypsum targets were measured. Using the bulk density of the projectile, the surface diameter and depth for basalt and the pit diameter and depth for porous gypsum were scaled using the pi-scaling law for crater formation in the strength regime. The numerical code iSALE was used to simulate the impact of projectiles of various shapes and interior structure with similar bulk densities. Results show that the distributions of the maximum (peak) pressure experienced and particle velocity in the targets were similar regardless of projectile shape and interior structure, implying that the dimensions of the final craters were almost identical. This is consistent with the experimental results. Thus, we conclude that the size of the craters formed by the impact of projectiles with different shape and interior structure can be scaled using a conventional scaling law in the strength regime, using bulk density as projectile density. Graphical abstractSpringer Science and Business Media LLC, Aug. 2022, Earth, Planets and Space, 74(1) (1)[Refereed]Scientific journal
- American Geophysical Union (AGU), Aug. 2022, Journal of Geophysical Research: Planets, 127(8) (8)[Refereed]Scientific journal
- Abstract Shock metamorphism of minerals in meteorites provides insights into the ancient Solar System. Calcite is an abundant aqueous alteration mineral in carbonaceous chondrites. Return samples from the asteroids Ryugu and Bennu are expected to contain calcite‐group minerals. Although shock metamorphism in silicates has been well studied, such data for aqueous alteration minerals are limited. Here, we investigated the shock effects in calcite with marble using impact experiments at the Planetary Exploration Research Center of Chiba Institute of Technology. We produced decaying compressive pulses with a smaller projectile than the target. A metal container facilitates recovery of a sample that retains its pre‐impact stratigraphy. We estimated the peak pressure distributions in the samples with the iSALE shock physics code. The capability of this method to produce shocked grains that have experienced different degrees of metamorphism from a single experiment is an advantage over conventional uniaxial shock recovery experiments. The shocked samples were investigated by polarizing microscopy and X‐ray diffraction analysis. We found that more than half of calcite grains exhibit undulatory extinction when peak pressure exceeds 3 GPa. This shock pressure is one order of magnitude higher than the Hugoniot elastic limit (HEL) of marble, but it is close to the HEL of a calcite crystal, suggesting that the undulatory extinction records dislocation‐induced plastic deformation in the crystal. Finally, we propose a strategy to re‐construct the maximum depth of calcite grains in a meteorite parent body, if shocked calcite grains are identified in chondrites and/or return samples from Ryugu and Bennu.American Geophysical Union (AGU), Jun. 2022, Journal of Geophysical Research: Planets, 127(6) (6), English[Refereed]Scientific journal
- Radiation phenomena are usually observed during fracture of quartz-bearing rocks. Since quartz is a piezoelectric material, the associated electrical processes such as the electrification of fracture surface and the flight of electrons between fracture surfaces should be important for radiation during fractures. In this article, supposing that travelling electrons between crack surfaces cause the radiation, we experimentally investigate X-ray emission in a vacuum and visible-light emission in the atmosphere during rock and mineral fracture and verify the consistency of both emissions. The number of electrons in flight between surfaces during fracture that result in X-ray is estimated and the comparison with the number of photons in visible light suggests that one electron repeatedly collides with N2 molecules. The estimated number of collisions resulting in a visible-light emission is slightly less than the expected upper limit. This is reasonable because the collision would cause the light emission not always in the wavelengths of visible light. Moreover, the number of electrons resulting in X-rays is comparable with the number of electrons resulting in the emission of radio waves during fracture obtained in previous studies. Thus, we conclude that the radiations during fracture can be attributed to the flight of electrons between fracture surfaces. Finally, we evaluate the feasibility of observing the X-ray emission in planetary exploration and the radio waves and the visible light in natural earthquakes and find that these radiations are observable.2022, Minerals, 12(6) (6), English[Refereed]Scientific journal
- The Hayabusa2 spacecraft investigated the C-type (carbonaceous) asteroid (162173) Ryugu. The mission performed two landing operations to collect samples of surface and subsurface material, the latter exposed by an artificial impact. We present images of the second touchdown site, finding that ejecta from the impact crater was present at the sample location. Surface pebbles at both landing sites show morphological variations ranging from rugged to smooth, similar to Ryugu’s boulders, and shapes from quasi-spherical to flattened. The samples were returned to Earth on 6 December 2020. We describe the morphology of >5 grams of returned pebbles and sand. Their diverse color, shape, and structure are consistent with the observed materials of Ryugu; we conclude that they are a representative sample of the asteroid.American Association for the Advancement of Science (AAAS), 2022, Science, 375(6584) (6584), 1011 - 1016, English[Refereed]Scientific journal
- 2022, Progress in Earth and Planetary Science, 9(1) (1), English[Refereed]Scientific journal
- A projectile impact onto a granular target produces an ejecta curtain with heterogeneous material distribution. Understanding how the heterogeneous pattern forms is potentially important for understanding how crater rays form. Previous studies predicted that the pattern formation is induced by inelastic collisions of ejecta particles in early stages of crater formation and terminated by the ejecta's expanding motion. In this study, we test this prediction based on a hypervelocity impact experiment together with N-body simulations where the trajectories of inelastically colliding granular particles are calculated. Our laboratory experiment suggests that pattern formation is already completed on a timescale comparable to the geometrical expansion of the ejecta curtain, which is ~10 μs in our experiment. Our simulations confirm the previous prediction that the heterogeneous pattern grows through initial inelastic collisions of particle clusters and subsequent geometric expansion with no further cluster collisions. Furthermore, to better understand the two-stage evolution of the mesh pattern, we construct a simple analytical model that assumes perfect coalescence of particle clusters upon collision. The model shows that the pattern formation is completed on the timescale of the system's expansion independently of the initial conditions. The model also reproduces the final size of the clusters observed in our simulations as a function of the initial conditions. It is known that particles in the target are ejected at lower speeds with increased distance to the impact point. The difference in the ejection speed of the particles may result in the evolution of the mesh pattern into rays....Dec. 2021, Planetary Science Journal, 2(6) (6), English[Refereed]Scientific journal
- American Geophysical Union (AGU), Apr. 2021, Geophysical Research Letters, 48(8) (8), English[Refereed]Scientific journal
- American Geophysical Union (AGU), Apr. 2021, Geophysical Research Letters, 48(7) (7), English[Refereed]Scientific journal
- 2021, Review of High Pressure Science and Technology/Koatsuryoku No Kagaku To Gijutsu, 31(3) (3), Japanese[Refereed]Scientific journal
- The loss of volatile material from asteroid Ryugu was not caused solely by heating from hypervelocity impacts as previously believed, suggest impact experiments conducted at speeds comparable to those expected in the main asteroid beltCarbonaceous asteroids, including Ryugu and Bennu, which have been explored by the Hayabusa2 and OSIRIS-REx missions, were probably important carriers of volatiles to the inner Solar System. However, Ryugu has experienced significant volatile loss, possibly from hypervelocity impact heating. Here we present impact experiments at speeds comparable to those expected in the main asteroid belt (3.7 km s(-1) and 5.8 km s(-1)) and with analogue target materials. We find that loss of volatiles from the target material due to impacts is not sufficient to account for the observed volatile depletion of Ryugu. We propose that mutual collisions in the main asteroid belt are unlikely to be solely responsible for the loss of volatiles from Ryugu or its parent body. Instead, we suggest that additional processes, for example associated with the diversity in mechanisms and timing of their formation, are necessary to account for the variable volatile contents of carbonaceous asteroids.SPRINGERNATURE, 2021, Communications Earth and Environment, 2(1) (1), English[Refereed]Scientific journal
- Elsevier BV, Jan. 2021, Planetary and Space Science, 195, 105141 - 105141, English[Refereed]Scientific journal
- Mar. 2020, Icarus, 339[Refereed]Scientific journal
- Last, 2020, Monthly Notices of the Royal Astronomical Society, 494(1) (1), English[Refereed]Scientific journal
- 2020, Journal of Geophysical Research: Planets, 125(4) (4), English[Refereed]Scientific journal
- Just accepted.2020, Scientific Reports, 9(1) (1), 19833 - 19833, English, International magazine[Refereed]Scientific journal
- Formation process of the pattern observed in impact-induced ejectaJust accepted.2020, Icarus, English[Refereed]Scientific journal
- Accepted.Dec. 2019, Geophysical Research Letters, 46(23) (23), English[Refereed]Scientific journal
- Elsevier BV, Nov. 2019, Life Sciences in Space Research, 23, 73 - 84, English[Refereed]Scientific journal
- Elsevier BV, Nov. 2019, Life Sciences in Space Research, 23, 85 - 100, English[Refereed]Scientific journal
- Dry lakebeds might constitute large volatile reservoirs on Mars. Hypervelocity impacts onto ancient dry lakebeds would have affected the volatile distribution on Mars. We developed a new experimental method to investigate the response of evaporitic minerals (halite and gypsum) to impact shocks in an open system. This technique does not result in chemical contamination from the operation of the gas gun. The technique is termed the "two-valve method," and the gun system is located in the Planetary Exploration Research Center, Chiba Institute of Technology, Japan. We detected the vaporization of halite at 31 GPa and devolatilization from gypsum at 11 GPa, suggesting that impact-induced volatile release from dry lakebeds has periodically occurred throughout Martian history. The vaporization of halite deposits might have enhanced the production of perchlorates, which are found globally on Mars. The water loss from gypsum possibly explains the coexisting types of Ca-sulfates found in Gale Crater.Plain Language Summary We used a new experimental technique to investigate the result of a meteoroid impact into an evaporitic deposit on Mars. Although two-stage light gas guns are ideal projectile launchers, the dirty gas from the gun has been a long-standing limitation of this technique that so far greatly complicated analysis of the vapors that are generated due to such impacts. Our new method overcomes this limitation and allows us to measure impact-generated vapor from evaporitic minerals. We detected NaCl vapor from halite and water vapor from gypsum at velocities lower than the typical impact velocities onto Mars. This suggests that volatile release from ancient dry lakebeds has periodically occurred throughout Martian history, due to stochastic meteoroid impacts. The nature of perchlorates and Ca-sulfates found on Mars can be interpreted as the result of hypervelocity impacts onto dry lakebeds rich in evaporitic minerals.AMER GEOPHYSICAL UNION, Jul. 2019, GEOPHYSICAL RESEARCH LETTERS, 46(13) (13), 7258 - 7267, English[Refereed]Scientific journal
- © 2018 Impact craters are among the most prominent topographic features on planetary bodies. Crater scaling laws allow us to extract information about the impact histories on the host bodies. The π-group scaling laws (e.g., Holsaplle and Schmidt, 1982) have been constructed based on the point-source approximation, dimensional analysis, and the results from laboratory and numerical impact experiments. Recent laboratory and numerical impact experiments, however, demonstrated that the scaling parameters themselves exhibits complex behavior against the change in the impact conditions and target properties. Since impact experiments are expensive and time-consuming in terms of obtaining new scaling constants, it is not feasible to explore the entire parameter space via experiments. Here, we propose an alternative, fully analytical method to predict impact outcomes, including the ejection velocity distribution and transient crater radii, based on impact cratering mechanics. This approach is based on the Maxwell Z-model (Maxwell, 1977) and the residual velocity (Melosh, 1985). Given that the shapes of the streamlines of the excavation flow and the kinetic energy in a given streamtube are known, we can calculate the ejecta velocity distribution and investigate the cessation of crater growth. We present analytical expressions of (1) the proportionality relation between the ejection velocity and the ejection position, (2) the radius of a growing crater as a function of time, and (3) the transient crater radii in the gravity- and strength-dominated regimes. Since we focused on obtaining analytical solutions in this study, a number of simplifications are employed, such as a priori assumption of the direction of the velocity vectors of the excavating materials, the neglect of the effects of dry friction, metal-like targets with a constant yield strength. Due to the simplifications in the strength model, the accuracy of the prediction in the strength-dominated cratering regime is relatively low. Our model reproduces the power-law behavior of the ejecta velocity distribution and the approximate time variation of a growing crater predicted by π-group scaling laws. In our model, the transient crater radius depends strongly on the shape exponent Z, the shock decay exponent n, and the exponent m pertaining to the residual velocity. Thus, the nature of shock propagation and the thermodynamic response of the shocked media, which cannot be addressed by dimensional analyses as a matter of principle, are naturally included in our estimation. The predicted radii under typical impact conditions mostly converge to a region between the two typical scaling lines for dry and wet sands predicted by the π-group scaling laws, strongly supporting the notion that the new method is one of the simplest ways to predict impact outcomes, as it provides analytical solutions. Our model could serve as a quick-look tool to estimate the impact outcome under a given set of conditions, and it might provide new insights into the nature of impact excavation processes.Jan. 2019, Icarus, 317, 135 - 147, English[Refereed]Scientific journal
- 火星隕石は火星の表層物質が地球に到達することがあるという物的証拠である. ところが, 衝撃物理学の原理に従うと火星表層物質が宇宙空間に射出されるという力学的制約(放出速度> 5 km/s)と, 火星隕石の岩石学的分析から得られる制約(最大経験圧力<50 GPa)を同時に満たすことはできない. 我々は先行研究に比べて一桁以上高い空間解像度で数値衝突計算を実施し, 火星隕石放出過程について詳細に調査した. その結果, 衝撃波と膨張波の伝播によって加速された物質が玉突き事故を起こすことによって, 心太式に加速されることによって衝撃物理学から決まる上限の速度よりも高速度の放出が達成されることがわかった. 我々はこの緩やかな加速を｢後期加速｣と名付けた. 本稿ではこの新発見について紹介し, 天体衝突による高速度放出についての未解明点を整理する.The Japanese Society for Planetary Sciences, Sep. 2018, 日本惑星科学会誌 遊・星・人, 27(3) (3), 197‐206 - 206, Japanese[Refereed]
- We propose that the shape of impact fragments reflects their fragmentation mechanisms the fragmentation process that generates smaller fragments (fractal crack bifurcation) produces the shapes frequently observed in the previous studies, and those that generate larger fragments (spallation, random tessellation, and geometrical effects) produce flatter fragments. Fragment shape analyses derived from hypervelocity impact experiments in a variety of mass distribution ranges qualitatively support this view.Academic Press Inc., Jul. 2018, Icarus, 309, 260 - 264, English[Refereed]Scientific journal
- Impact-cratering processes on small bodies are thought to be mainly controlled by the local material strength because of their low surface gravity, and craters that are as large as the parent bodies should be affected by the target curvature. Although cratering processes on planar surfaces in the strength controlled regime have been studied extensively, the mechanism by which target curvature affects the cratering processes remains unclear. Herein, we report on a series of impact experiments that used spherical targets with various diameters. The resultant craters consisted of a deep circular pit and an irregular-shaped spall region around the pit, which is consistent with the features reported in a number of previous cratering experiments on planar surfaces. However, the volume and radius of the craters increased with the normalized curvature. The results indicate that the increase in the spall-region volume and radius mainly contributes to the increase in the whole crater volume and radius, although the volume, depth, and radius of pits remain constant with curvature. The results of our model indicate that the geometric effect due to curvature (i.e., whereby the distance from the equivalent center to the target free surface is shorter for higher curvature values) contributes to increases in the cratering efficiency. Our results suggest that the impactors that produce the largest craters (basins) on some asteroids are thus smaller than what is estimated by current scaling laws, which do not take into account the curvature effects. (C) 2017 Elsevier Inc. All rights reserved.ACADEMIC PRESS INC ELSEVIER SCIENCE, Feb. 2018, ICARUS, 301, 1 - 8, English[Refereed]Scientific journal
- Hypervelocity ejection of material by impact spallation is considered a plausible mechanism for material exchange between two planetary bodies. We have modeled the spallation process during vertical impacts over a range of impact velocities from 6 to 21 km/s using both grid- and particle-based hydrocode models. The Tillotson equations of state, which are able to treat the nonlinear dependence of density on pressure and thermal pressure in strongly shocked matter, were used to study the hydrodynamic thermodynamic response after impacts. The effects of material strength and gravitational acceleration were not considered. A two-dimensional time-dependent pressure field within a 1.5-fold projectile radius from the impact point was investigated in cylindrical coordinates to address the generation of spalled material. A resolution test was also performed to reject ejected materials with peak pressures that were too low due to artificial viscosity. The relationship between ejection velocity v(eject) and peak pressure P-peak was also derived. Our approach shows that "late-stage acceleration" in an ejecta curtain occurs due to the compressible nature of the ejecta, resulting in an ejection velocity that can be higher than the ideal maximum of the resultant particle velocity after passage of a shock wave. We also calculate the ejecta mass that can escape from a planet like Mars (i.e., v(eject) > 5 km/s) that matches the petrographic constraints from Martian meteorites, and which occurs when P-peak = 30-50 GPa. Although the mass of such ejecta is limited to 0.1-1 wt% of the projectile mass in vertical impacts, this is sufficient for spallation to have been a plausible mechanism for the ejection of Martian meteorites. Finally, we propose that impact spallation is a plausible mechanism for the generation of tektites. (C) 2017 Elsevier Inc. All rights reserved.ACADEMIC PRESS INC ELSEVIER SCIENCE, Feb. 2018, ICARUS, 301, 219 - 234, English[Refereed]Scientific journal
- Hypervelocity impacts cause significant heating of planetary bodies. Such events are recorded by a reset of 40Ar-36Ar ages and/or impact melts. Here we investigate the influence of friction and plastic deformation in shock-generated comminuted rocks on the degree of impact heating using the iSALE shock-physics code. We demonstrate that conversion from kinetic to internal energy in the targets with strength occurs during pressure release, and additional heating becomes significant for low-velocity impacts (< 10 km s−1). This additional heat reduces the impact-velocity thresholds required to heat the targets with the 0.1 projectile mass to temperatures for the onset of Ar loss and melting from 8 and 10 km s−1, respectively, for strengthless rocks to 2 and 6 km s−1 for typical rocks. Our results suggest that the impact conditions required to produce the unique features caused by impact heating span a much wider range than previously thought.Blackwell Publishing Ltd, Jan. 2018, Geophysical Research Letters, 45(2) (2), 620 - 626, English[Refereed]Scientific journal
- Japan Society for Aeronautical and Space Sciences, 2018, Transactions of the Japan Society for Aeronautical and Space Sciences, 16(7) (7), 691 - 697, English[Refereed]Scientific journal
- We examine the history of the loss and replenishment of the Martian atmosphere using elemental and isotopic compositions of nitrogen and noble gases. The evolution of the atmosphere is calculated by taking into consideration various processes: impact erosion and replenishment by asteroids and comets, atmospheric escape induced by solar radiation and wind, volcanic degassing, and gas deposition by interplanetary dust particles. Our model reproduces the elemental and isotopic compositions of N and noble gases (except for Xe) in the Martian atmosphere, as inferred from exploration missions and analyses of Martian meteorites. Other processes such as ionization-induced fractionation, which are not included in our model, are likely to make a large contribution in producing the current Xe isotope composition. Since intense impacts during the heavy bombardment period greatly affect the atmospheric mass, the atmospheric pressure evolves stochastically. Whereas a dense atmosphere preserves primitive isotopic compositions, a thin atmosphere on early Mars is severely influenced by stochastic impact events and following escape-induced fractionation. The onset of fractionation following the decrease in atmospheric pressure is explained by shorter timescales of isotopic fractionation under a lower atmospheric pressure. The comparison of our numerical results with the less fractionated N (N-15/N-14) and Ar (Ar-38/Ar-36) isotope compositions of the ancient atmosphere recorded in the Martian meteorite Allan Hills 84001 provides a lower limit of the atmospheric pressure in 4 Ga to preserve the primitive isotopic compositions. We conclude that the atmospheric pressure was higher than approximately 0.5 bar at 4 Ga. (C) 2017 Elsevier Inc. All rights reserved.ACADEMIC PRESS INC ELSEVIER SCIENCE, Jan. 2018, ICARUS, 299, 443 - 459, English[Refereed]Scientific journal
- 高速度天体衝突は惑星の表層平均場に非平衡場を作り出し, 惑星システムへのパルス的な環境変動を与える. そこからの緩和過程は惑星システムそのものに依存し, その多様性を強調する可能性がある. 筆者らの研究グループは平衡場を乱す主要因であると考えられる高エネルギー密度領域の物理・化学過程に注目し, その素過程の解明を目指して実験的研究を進めてきた. 本稿ではその成果を紹介するとともに, 近年の惑星形成理論の進展と合わせて初期太陽系天体の表層進化を推定するための展望について述べる.The Japanese Society for Planetary Sciences, Dec. 2016, 日本惑星科学会誌 遊・星・人, 25(4) (4), 136‐148 - 148, Japanese[Refereed]
- We carried out laser shock experiments and wholly recovered shocked olivine and quartz samples. We investigated the petrographic features based on optical micrographs of sliced samples and found that each recovered sample comprises three regions, I (optically dark), II (opaque), and III (transparent). Scanning electron microscopy combined with electron backscattered diffraction shows that there are no crystal features in the region I; the materials in the region I have once melted. Moreover, numerical calculations performed with the iSALE shock physics code suggest that the boundary between regions II and III corresponds to Hugoniot elastic limit (HEL). Thus, we succeeded in the recovery of the entire shocked samples experienced over a wide range of pressures from HEL (similar to 10 GPa) to melting pressure (similar to 100 GPa) in a hierarchical order.WILEY, Jun. 2016, METEORITICS & PLANETARY SCIENCE, 51(6) (6), 1153 - 1162, English[Refereed]Scientific journal
- <p>It is widely believed that the Hadean Earth suffered an intense impact bombardment. Shock vaporization/subsequent chemical reaction is one of the most curious processes on the Hadean Earth because it leads to unique chemical reactions never driven under a mean field on the Earth due to the injection of reducing materials with a significant amount of kinetic energy. Here, I review a recent research development on the nature of impactors at the terminal stage of planetary accretion. After a long discussion over a few decades, a self-consistent model referred to as "a sawtooth-like timeline" has been proposed. Then, I introduce a framework to understand shock-induced chemistry based on the entropy method. Hypervelocity impact experiments in an open system would be essential to investigate the impact-generated chemical species quantitatively. Finally, I discuss a future plan to estimate the Hadean environment on Earth from an impact laboratory. An intense and impulsive perturbation due to hypervelocity impacts might cause the release of a large amount of free energy into a prebiotic field and produce unique geochemical features, such as isotopic anomalies in oxygen and sulfur in sediments, through the recovery processes. A combination analysis with the recent model for the impact bombardment and a more detailed model for impact-induced chemical reactions will allow us to re-construct the surface environment on the Hadean Earth.</p>一般社団法人日本地球化学会, 2016, Chikyukagaku, 50(3) (3), 135 - 154, Japanese[Refereed]
- The fate of surface water on Venus is one of the most important outstanding problems in comparative planetology. Although Venus should have had a large amount of surface water (like the Earth) during its formation, the current water content on the Venusian surface is only 1 part in 100 000 of that of the mass of Earth's oceans. Here a new concept is proposed to explain water removal on a steam-covered proto Venus, referred to as "impact-driven planetary desiccation". Since a steam atmosphere is photochemically unstable, water vapor dissociates into hydrogen and oxygen. Then, hydrogen escapes easily into space through hydrodynamic escape driven by strong extreme ultraviolet radiation from the young Sun. The focus is on the intense impact bombardment during the terminal stage of planetary accretion as generators of a significant amount of reducing agent. The fine-grained ejecta remove the residual oxygen, the counter part of escaped hydrogen, via the oxidation of iron-bearing rocks in a hot atmosphere. Thus, hypervelocity impacts cause net desiccation of the planetary surface. I constructed a stochastic cratering model using a Monte Carlo approach to investigate the cumulative mass of nonoxidized, ejected rocks due to the intense impact bombardment. The ejecta mass after each impact was calculated using the pi-group scaling laws and a modified Maxwell's Z model. The effect of projectile penetration into the ground on the ejecta mass was also included. Next, an upper limit on the total amount of removed water was calculated using the stoichiometric limit of the oxidation of basaltic rocks, taking into account the effect of fast H-2 escape. It is shown that a thick steam atmosphere with a mass equivalent to that of the terrestrial oceans would be removed. The cumulative mass of rocky ejecta released into the atmosphere reaches 1 wt% of the host planet, which is 10 000 times of the current mass of the Earth's atmosphere. These results strongly suggest that chemical reactions between such large amounts of ejecta and planetary atmospheres are among the key factors required to understand atmospheric mass and its composition, not only in the Solar System but also in extrasolar systems. (C) 2015 Elsevier B.V. All rights reserved.ELSEVIER SCIENCE BV, Nov. 2015, EARTH AND PLANETARY SCIENCE LETTERS, 429, 181 - 190, English[Refereed]Scientific journal
- The bulk chemical compositions of planets are uncertain, even for major elements such as Mg and Si. This is due to the fact that the samples available for study all originate from relatively shallow depths. Comparison of the stable isotope compositions of planets and meteorites can help overcome this limitation. Specifically, the non-chondritic Si isotope composition of the Earth's mantle was interpreted to reflect the presence of Si in the core, which can also explain its low density relative to pure Fe-Ni alloy. However, we have found that angrite meteorites display a heavy Si isotope composition similar to the lunar and terrestrial mantles. Because core formation in the angrite parent-body (APB) occurred under oxidizing conditions at relatively low pressure and temperature, significant incorporation of Si in the core is ruled out as an explanation for this heavy Si isotope signature. Instead, we show that equilibrium isotopic fractionation between gaseous SiO and solid forsterite at similar to 1370 K in the solar nebula could have produced the observed Si isotope variations. Nebular fractionation of forsterite should be accompanied by correlated variations between the Si isotopic composition and Mg/Si ratio following a slope of similar to 1, which is observed in meteorites. Consideration of this nebular process leads to a revised Si concentration in the Earth's core of 3.6 (+6.0/-3.6) wt% and provides estimates of Mg/Si ratios of bulk planetary bodies. (C) 2015 Elsevier B.V. All rights reserved.Last, ELSEVIER SCIENCE BV, Oct. 2015, EARTH AND PLANETARY SCIENCE LETTERS, 427, 236 - 248, English[Refereed]Scientific journal
- A series of hypervelocity impact experiments was conducted in a new laboratory at Planetary Exploration Research Center of Chiba Institute of Technology (Japan). We present the results of high-speed imaging observations of impact jetting during blunt-body penetration under oblique impacts. The observations were sampled at a frame rate of 100nsframe(-1), which is much shorter than the characteristic time of projectile penetration under our experimental conditions. The maximum jet velocity was obtained as a function of both impact velocity and the contrast of shock impedance between a projectile and target, enabling us to test theoretical models of impact jetting during oblique impacts of spherical projectiles. We find that the jet velocities measured in this study are much slower than the prediction by the standard theory based on the previous experimental/theoretical results of collisions between two metal plates. A decaying shock pressure during blunt-body penetration is a possible origin of the discrepancy. We also present a new formulation of the jet velocity with the equations of state for realistic materials. The particle velocities of ejected materials from a free surface are calculated using the Riemann invariant along the isentropes and the Tillotson equations of state in this study. Based on the extremely high velocity of the jet, we point out that impact jetting might contribute to chemistry near the ground surface of planets/satellites with a thick atmosphere, such as Titan.AMER GEOPHYSICAL UNION, Jul. 2015, JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, 120(7) (7), 1237 - 1251, English[Refereed]Scientific journal
- In order to investigate impact production of carbonaceous products by asteroids on Titan and other satellites and planets, simulation experiments were carried out using a 2-stage light gas gun. A small polycarbonate or metal bullet with about 6.5 km/s was injected into a pressurized target chamber filled with 1 atm of nitrogen gas, to collide with a ice + iron target or an iron target or a ice + hexane + iron target. After the impact, black soot including fine particles was deposited on the chamber wall. The soot was carefully collected and analyzed by High Performance Liquid Chromatography (HPLC), Fourier Transform Infrared Spectroscopy (FT-IR), and Laser Desorption Time-of-Flight Mass Spectrometry (LD-ToF-MS). As a result of the HPLC analysis, about 0.04-8 pmol of glycine, and a lesser amount of alanine were found in the samples when the ice + hexane + iron target was used. In case of the ice + iron target and the iron target, less amino acids were produced. The identification of the amino acids was also supported by FTIR and LD-ToF-MS analysis.SPRINGER, Jun. 2015, ORIGINS OF LIFE AND EVOLUTION OF BIOSPHERES, 45(1-2) (1-2), 195 - 205, English[Refereed]Scientific journal
- 超高速天体衝突で生じる蒸発現象は惑星大気形成にとって重要だが,ケイ酸塩岩の蒸発は10km/s超の高速度でないと高い効率で生じないため実験的研究が困難であった.しかし,この事情はレーザー銃の開発と2段式軽ガス銃の進歩によって大きく変化した.また,高速分光法および質量分析法の開発も衝突脱ガス気体の分子組成計測の実現に重要な役割を果たした.これらの実験手法の進歩は,理論計算とともに惑星大気の進化過程の理解に大きな進展をもたらした.本稿では,最近の研究によって確立した実験手法を紹介しながら,それらの実験が明らかにした衝突蒸気雲の描像と惑星大気進化への影響を解説する.Last, 日本惑星科学会, 2015, Planetary People, 24(3) (3), 181 - 190, Japanese[Refereed]
- An optical spike is sometimes observed prior to the main flash in high-velocity impact experiments. The spikes are particularly noticeable in the case of Nylon66 projectiles. In this study, we conducted experiments in which Nylon66 spheres impacted the flat surfaces of Nylon66 blocks perpendicularly at 7 km s(-1). We observed the impact phenomena by using an ultra-high-speed camera and high-temporal-resolution photometers to identify the cause of the spikes. High-speed photographs show that the entire projectile was shining while it was penetrating a target. Glaring light from the shock front propagating in the projectile is assumed to become diffused within the translucent projectile and then radiated from its surface. The blackbody radiation from the shock front at 3600 K, which is calculated based on a one-dimensional shock model, accounts for the radiative intensities measured by the photometers. A sub-spike was observed just after the main spike in all the experiments conducted, the cause of which was not ascertained. (C) 2015 The Authors. Published by Elsevier Ltd.ELSEVIER SCIENCE BV, 2015, PROCEEDINGS OF THE 2015 HYPERVELOCITY IMPACT SYMPOSIUM (HVIS 2015), 103, 657 - 662, English[Refereed]International conference proceedings
- The mass extinction event at the Cretaceous/Palaeogene boundary 65.5 Myr ago has been widely attributed to the Chicxulub impact(1, 2), but the mechanisms of extinction remain debated(1,3-6). In the oceans, near-surface planktonic foraminifera suffered severe declines, in contrast to the relatively high survival rates of bottom-dwelling benthic foraminifera(7). The vapour produced by an impact into Chicxulubs target rocks, which include sulphate-rich anhydrite, could have led to global acid rain, which can explain the pattern of oceanic extinctions(4, 5). However, it has been suggested that most of the sulphur in the target rocks would have been released as sulphur dioxide and would have stayed in the stratosphere for a long time(6). Here we show, from impact experiments into anhydrite at velocities exceeding 10 km s(-1), that sulphur trioxide dominates over sulphur dioxide in the resulting vapour cloud. Our experiments suggest that the Chicxulub impact released a huge quantity of sulphur trioxide into the atmosphere, where it would have rapidly combined with water vapour to form sulphuric acid aerosol particles. We also find, using a theoretical model of aerosol coagulation following the Chicxulub impact, that larger silicate particles ejected during the impact efficiently scavenge sulphuric acid aerosol particles and deliver the sulphuric acid to the surface within a few days. The rapid surface deposition of sulphuric acid would cause severe ocean acidification and account for preferential extinction of planktonic over benthic foraminifera.NATURE PUBLISHING GROUP, Apr. 2014, NATURE GEOSCIENCE, 7(4) (4), 279 - 282, English[Refereed]Scientific journal
- Cyanide compounds are amongst the most important molecules of the origin of life. Here, we demonstrate the importance of mid-size (0.1-1 km in diameter) hence frequent meteoritic impacts to the cyanide inventory on the early Earth. Subsequent aerodynamic ablation and chemical reactions with the ambient atmosphere after oblique impacts were investigated by both impact and laser experiments. A polycarbonate projectile and graphite were used as laboratory analogs of meteoritic organic matter. Spectroscopic observations of impact-generated ablation vapors show that laser irradiation to graphite within an N-2-rich gas can produce a thermodynamic environment similar to that produced by oblique impacts. Thus, laser ablation was used to investigate the final chemical products after this aerodynamic process. We found that a significant fraction (> 0.1 mol%) of the vaporized carbon is converted to HCN and cyanide condensates, even when the ambient gas contains as much as a few hundred mbar of CO2. As such, the column density of cyanides after carbon-rich meteoritic impacts with diameters of 600 m would reach similar to 10 mol/m(2) over similar to 10(2) km(2) under early Earth conditions. Such a temporally and spatially concentrated supply of cyanides may have played an important role in the origin of life.SPRINGER, Jun. 2013, ORIGINS OF LIFE AND EVOLUTION OF BIOSPHERES, 43(3) (3), 221 - 245, English[Refereed]Scientific journal
- Small primitive bodies were presumably highly porous when they formed and some still have low densities that are indicative of a high pore content. Therefore, after their formation, interplanetary dust impacting on their surface may have been captured because of their porous structure. The mechanism of dust penetration is thus of importance to understand the evolution of small bodies and the origin of their internal dust particles. Impact experiments of sintered glass-bead targets characterized by 80%, 87%, and 94% bulk porosity were conducted using metal and basalt projectiles at impact velocities ranging from 1.6 to 7.2 km s(-1). Track morphology and penetration processes were analyzed using both X-ray tomography and a flash X-ray system. Two types of track were observed, as previously also found in the Stardust aerogel: a thin and long track (carrot-shaped track), and a "bulb" with tails (bulb-shaped track). The track shape changed with initial dynamic pressure. We found that the transition between "carrot" and "bulb" occurred at a pressure of roughly 20 times the projectile's tensile strength. The deceleration process of projectiles without severe deformation and fragmentation was reproduced by a drag equation composed of an inertia drag that was proportional to the square of the projectile's velocity and a constant drag proportional to the target's compressive strength. We applied this deceleration equation to silicate dust penetrating into hypothetical porous icy bodies which were homogeneous on much smaller scales than the impacting dust particles. The penetration depth was approximately 100 times the projectile diameter for the bodies with 90% porosity. (C) 2013 Elsevier Inc. All rights reserved.ACADEMIC PRESS INC ELSEVIER SCIENCE, May 2013, ICARUS, 224(1) (1), 209 - 217, English[Refereed]Scientific journal
- We systematically conducted impact cratering experiments with sedimentary rocks at 0.8-7.1 km/s using various projectiles with 1.1-15 g/cm(3) in density. The crater diameter, depth, and volume are investigated and compared with the results for igneous rocks. Then, using the non-dimensional parameters, the normalized crater diameter pi(D), the normalized depth pi(d), the normalized volume pi(V), the target strength per specific energy pi(3), and the target and projectile density ratio pi(4), the scaling laws, pi(D) = (1.43 +/- 0.25)pi(-0.22 +/- 0.02)(3) pi(0.11 +/- 0.07)(4), pi(d) = (0.22 +/- 0.04)pi(-0.25 +/- 0.02)(3) pi(0.01 +/- 0.05)(4), and pi(V) = (0.11 +/- 0.04) pi(-0.71 +/- 0.05)(3) pi(0.23 +/- 0.17)(4), are obtained. The comparison with the results of igneous rocks suggests that the characteristic properties of sedimentary rocks such as the lower strength and the strong shock wave attenuation rate are actually effective for the cratering of sedimentary rocks.AMER GEOPHYSICAL UNION, Aug. 2012, JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, 117(8) (8), English[Refereed]Scientific journal
- The shock-induced decarbonation of non-porous calcite was investigated in an open system over a wide range of peak shock pressures using a two-stage light gas gun and a quadrupole mass spectrometer. We developed a new experimental technique that avoids chemical contamination from the acceleration gas used in the gun. High-speed imaging and spectroscopic observations were conducted simultaneously to investigate the validity of the experimental procedure. The decarbonation efficiency along the Hugoniot curve changed at around 50 GPa-the approximate incipient decarbonation pressure predicted by the previous theoretical studies. Decarbonation, albeit at a low efficiency, was detected at pressures below the 50 GPa threshold, as observed in previous experimental studies, possibly as a result of energy localization due to a process like shear banding. A simple theoretical model for shock-induced decarbonation during isentropic release was constructed based on the entropy method and the lever rule, assuming the experimental conditions. The predicted amount of released CO2 as a function of the peak shock pressure agreed well with the experimental results at pressures exceeding 50 GPa, strongly suggesting that the amount of shock-induced CO2 gas was determined only by the shock-induced entropy gain and by the entropies for incipient and complete decarbonation at the ambient pressure. In future experiments, the new method will be used for quantitative measurements of the chemical composition of impact-induced gases derived from other solid materials. The proposed method is useful in determining the peak shock pressure required for vaporization/devolatilization of geologic materials and for estimating the final chemical composition of impact-induced vapor clouds. (C) 2012 Elsevier B.V. All rights reserved.ELSEVIER SCIENCE BV, Jul. 2012, EARTH AND PLANETARY SCIENCE LETTERS, 337, 68 - 76, English[Refereed]Scientific journal
- NASA's LCROSS (Lunar Crater Observation and Sensing Satellite) mission was designed to explore the nature of previously detected enhanced levels of hydrogen near the lunar poles. The LCROSS mission impacted the spent upper stage of the launch vehicle into a permanently shadowed region of the lunar surface to create an ejecta plume. The resultant impact crater and plume were then observed by the LCROSS Shepherding Spacecraft as well as a cadre of telescopes on the Earth and in space to determine the nature of the materials contained within the permanently shadowed region. The Shepherding Spacecraft then became a second impactor which was also observed by multiple assets. The LCROSS Observation Campaign was a key component of the LCROSS mission. The goal of the Observation Campaign was to realize the scientific benefits of extending the LCROSS observations to multiple ground and space-based assets. This paper describes the LCROSS Observation Campaign and provides an overview of the Campaign coordination and logistics as well as a summary of the observation techniques utilized at a multitude of observatories. Lessons learned from the LCROSS Observation Campaign are also discussed to assist with the planning of future unique observing events.SPRINGER, May 2012, SPACE SCIENCE REVIEWS, 167(1-4) (1-4), 93 - 140, English[Refereed]Scientific journal
- We conducted a spectroscopic study of shock-heated silicate (diopside) and obtained the time evolution of the spectral contents, the line widths of emission lines, and the time- and irradiance-averaged peak shock temperatures. The peak shock pressures ranged from 330 to 760 GPa. Time-resolved emission spectra indicated that the initial spectrum was blackbody radiation; the spectrum evolved to yield several ionic emission lines, which in turn evolved to yield atomic lines at the later stages. The shock-heated diopside was highly dissociated and ionized, even though it is likely to have been subjected to high-pressure conditions near the liquid-vapor phase boundary. The time evolution of the spectra, from ions to atoms, strongly suggests that electron recombination occurred in the expanding shock-induced diopside vapor. The time- and irradiance-averaged peak shock temperatures at >330 GPa were lower than the theoretical Hugoniot curve, with a constant isochoric specific heat, indicating endothermic shock-induced ionization. Thus, we conclude that electrons behave as an important energy reservoir in energy partitioning via endothermic shock-induced ionization and subsequent exothermic electron recombination. This electron behavior leads to a higher degree of vaporization after isentropic release and a lower cooling rate due to the exothermic electron recombination in expanding impact-induced silicate vapors than previously expected. These results will affect the predictions associated with hypervelocity impact events in planetary science, such as the origin of the Moon and chemical reactions and production of silicate dust particles in impact-generated silicate vapor clouds.AMER GEOPHYSICAL UNION, Apr. 2012, JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, 117(4) (4), English[Refereed]Scientific journal
- We systematically conducted impact cratering experiments with sedimentary rocks at 0.8-7.1km/s using various projectiles with 1.1-15g/cm 3 in density. The crater diameter, depth, and volume are investigated and compared with the results for igneous rocks. Then, using the non-dimensional parameters, the normalized crater diameter D, the normalized depth d, the normalized volume V, the target strength per specific energy 3, and the target and projectile density ratio 4, the scaling laws, D = (1.43 0.25) 3-0.220.0240.110.07, d = (0.22 0.04) 3-0.250.0240.010.05, and V = (0.11 0.04) 3-0.710.0540.230.17, are obtained. The comparison with the results of igneous rocks suggests that the characteristic properties of sedimentary rocks such as the lower strength and the strong shock wave attenuation rate are actually effective for the cratering of sedimentary rocks. © 2012. American Geophysical Union. All Rights Reserved.2012, Journal of Geophysical Research E: Planets, 117(8) (8)[Refereed]Scientific journal
- We conducted time-resolved spectroscopic observations of shock-heated quartz and forsterite using a high-power laser. The results revealed that ionization occur easily under shock-induced warm dense conditions. We compare the obtained temperatures on the Hugoniot with a few theories. The comparison suggests that the contribution of shock-induced ionization to the isochoric specific heat during shock compression is similar to 1 k(b)/atom for quartz and forsterite. Shock-induced ionization and subsequent electron recombination leads to a larger amount of vapor and may lead to dynamical and chemical evolution of silicate vapor clouds different from our current understandings.AMER INST PHYSICS, 2012, SHOCK COMPRESSION OF CONDENSED MATTER - 2011, PTS 1 AND 2, 1426, 855 - 858, English[Refereed]Scientific journal
- Accurate equation of state (EOS) is essential for understanding a variety of geologic processes associated with shock compression of materials. A number of highly sophisticated EOS's have been proposed (e. g., M-ANEOS and SESAME), covering a wide range of P-T conditions. However, they are complex and require many model parameters. Also, there are many occasions when only terminal thermodynamic variables after adiabatic decompression are needed. For example, when the terminal molecular composition of an impact-induced vapor is necessary, only the initial entropy gain and chemical reaction processes under low-P-T conditions need to be calculated. Then, only an on-Hugoniot EOS and a low-P-T EOS are necessary. To meet such demands, we derive a new semi-analytical on-Hugoniot EOS, which requires only the Hugoniot shock velocity parameters and specific heat, Gruneisen parameter, and its power-law exponent. Comparison with experimental data indicates that this EOS can reproduce on-Hugoniot entropy and temperature of ice and quartz very well, despite of its small number of model parameters.AMER INST PHYSICS, 2012, SHOCK COMPRESSION OF CONDENSED MATTER - 2011, PTS 1 AND 2, 1426, 895 - 898, English[Refereed]International conference proceedings
- The final chemical composition of vapor clouds created by the impacts higher than 10 km/s is important to investigate the evolution of the planetary surface environment and life. However, no previous experimental study has observed directly it because of experimental difficulties. In this study, we conducted hypervelocity impact experiments using a laser gun and measured the chemical compositions of the impact-generated sulfuric oxides directly. The result clearly shows that the sulfur oxides released by hypervelocity impacts are dominated by SO3, not SO2.AMER INST PHYSICS, 2012, SHOCK COMPRESSION OF CONDENSED MATTER - 2011, PTS 1 AND 2, 1426, 851 - 854, English[Refereed]International conference proceedings
- Flyer acceleration technique using high-power lasers has several advantages such as the achieved velocities higher than 10 km/s and non-contamination to the products generated by impacts. In this study, we show that a high-power laser can achieve impact velocities higher than 10 km/s up to 60 km/s using sheet flyers with a diameter of similar to 0.5 mm and a thickness of similar to 30 - 50 mu m and spherical projectiles with a diameter of 0.1 - 0.3 mm. We discuss the difference between sheet and spherical flyers in the energy transfer efficiency from laser energy to flyer kinetic energy.AMER INST PHYSICS, 2012, SHOCK COMPRESSION OF CONDENSED MATTER - 2011, PTS 1 AND 2, 1426, 847 - 850, English[Refereed]International conference proceedings
- The Lunar Crater Observation and Sensing Satellite (LCROSS) mission was an impact exploration searching for a volatile deposit in a permanently shadowed region (PSR) by excavating near-surface material. We conducted infrared spectral and imaging observations of the LCROSS impacts from 15 min before the first collision through 2 min after the second collision using the Subaru Telescope in order to measure ejecta dust and water. Such a ground-based observation is important because the viewing geometry and wavelength coverage are very different from the LCROSS spacecraft. We used the Echelle spectrograph with spectral resolution lambda/Delta lambda similar to 10,000 to observe the non-resonant H(2)O rotational emission lines near 2.9 mu m and the slit viewer with a K' filter for imaging observation of ejecta plumes. Pre-impact calculations using a homogeneous projectile predicted that 2000 kg of ejecta and 10 kg of H(2)O were excavated and thrown into the analyzed area immediately above the slit within the field of view (FOV) of the K' imager and the FOV of spectrometer slit, respectively. However, no unambiguous emission line of H(2)O or dust was detected. The estimated upper limits of the amount of dust and H(2)O from the main Centaur impact were 800 kg and 40 kg for the 3 sigma of noise in the analyzed area within the imager FOV and in the slit FOV, respectively. If we take 1 sigma as detection limit, the upper limits are 300 kg and 14 kg, respectively. Although the upper limit for water mass is comparable to a prediction by a standard theoretical prediction, that for dust mass is significantly smaller than that predicted by a standard impact theory. This discrepancy in ejecta dust mass between a theoretical prediction and our observation result suggests that the cratering process induced by the LCROSS impacts may have been substantially different from the standard cratering theory, possibly because of its hollow projectile structure. (C) 2011 Elsevier Inc. All rights reserved.ACADEMIC PRESS INC ELSEVIER SCIENCE, Jul. 2011, ICARUS, 214(1) (1), 21 - 29, English[Refereed]Scientific journal
- Time-resolved spectroscopic observations of silicate vaporization/ionization due to > 10km/s impacts惑星形成過程末期では>10km/sの"宇宙速度衝突"が頻繁に起こっていた.ところが,個々の衝突で生じる珪酸塩の相変化,蒸気内の化学反応の理解は進んでいない.本研究では珪酸塩鉱物試料を〜1TPaまで衝撃圧縮し,圧縮直後から断熱解放までを時間分解分光計測することで,エネルギー分配過程を直接観測した.その結果,宇宙速度衝突の場合,電子が電離/電子再結合を介してエネルギー貯蔵庫として振る舞うことが示唆された.この電子挙動は衝突後の珪酸塩蒸発率や衝突蒸気雲の運動に影響を与える.そのため巨大衝突後の原始月円盤の初期状態や後期隕石重爆撃期の大気形成,有機物合成過程に関する従来の理解が変化するかもしれない.日本惑星科学会, Dec. 2010, Planetary people, 19(4) (4), 332 - 339, Japanese[Refereed]
- We present the results of shock-induced silicate vaporization experiments using laser driven hypervelocity projectiles. In-situ spectroscopic observations of shock-heated quartz and diopside were conducted. We observed both atomic emission lines and blackbody continuum. Because emission lines occur only in a gas phase, this observation indicates that the incipient vaporization of silicates actually occurs at >10 km/s. We estimated the peak-shock temperatures from the blackbody spectra. The obtained results suggest that the temperature dependence of the isochoric specific heat C(v) depends rather strongly on material at extremely high pressures. Such difference in C(v) dependence on temperature will influence the impact vaporization efficiency. Thus, investigation on the C(v) of the other major silicates is necessary for understanding impact-related phenomena. Furthermore, the observed high intensity of emission lines shows the possibility that a variety of the thermodynamic variables of expanding silicate vapor can be measured with a higher speed spectrometer. Citation: Kurosawa, K., et al. (2010), In-situ spectroscopic observations of silicate vaporization due to >10 km/s impacts using laser driven projectiles, Geophys. Res. Lett., 37, L23203, doi: 10.1029/2010GL045330.AMER GEOPHYSICAL UNION, Dec. 2010, GEOPHYSICAL RESEARCH LETTERS, 37(23) (23), English[Refereed]Scientific journal
- A ground-based observation of LCROSS impact using the Subaru TelescopeLCROSS探査とは,月極域の永久影における氷の有無を,人工衝突によって表層を掘削して直接的に観測する探査である.我々はLCROSSの羊飼い探査衛星とは独立に月面上の水の有無を確認することと,羊飼い探査衛星の観測からは得られない放出物の鉛直分布に関する制約条件を得ることを目的として,すばる望遠鏡を用いて近赤外波長域での放出物の高分散分光および撮像観測を行った.事前の数値計算による予想では,かなりの量の水やダストの放出物が観測される見込みであったが,実際の観測データからはそれらは検出されなかった.そのため,水の分布などに対する情報は得られなかったが,本観測の結果はLCROSSの衝突が従来の標準的なクレーター形成モデルの予測とは大きくかけ離れたものであったことを示唆している.日本惑星科学会, Jun. 2010, Planetary people, 19(2) (2), 96 - 104, Japanese[Refereed]
- The impact velocities of asteroids on Earth and other terrestrial planets can be greater than 10 km/s, and impacts at these high velocities can produce significant effects on the planetary surfaces. However, since macroscopic (>similar to 0.1 mm) projectiles with an aspect ratio of similar to 1 are not easily accelerated to more than 10 km/s in laboratories, there are few detailed experimental studies. In this paper, we demonstrate that impact velocities greater than 10 km/s can be achieved with glass and aluminum projectiles of 0.1-0.3 mm in diameter using a high-power laser, GEKKO XII-HIPER at Institute of Laser Engineering, Osaka University. The velocity of the projectiles is estimated based on the images taken by high-speed X-ray streak and framing cameras. Projectiles collide into copper or LiF plate targets. The copper plates are recovered for analysis. The sizes of craters on the copper plates are not far from the extrapolations from previous work with lower velocities. A tantalum witness plate placed near the copper plates records a large number of secondary craters from each impact. In the case of the impacts of the LiF plates, we observe two emission lines of Li gas using a spectrometer with a streak camera. Thus, we can simulate the hypervelocity impacts with velocities higher than 10 km/s in laboratories.AMER GEOPHYSICAL UNION, Apr. 2010, JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, 115(4) (4), English[Refereed]Scientific journal
- Knowledge of pressure conditions is essential in understanding phase changes and chemical reactions. Although several methods have been proposed for the measurement of pressure in impact-induced vapor plumes, they are somewhat unreliable. In this study, we developed a pressure measurement method for vapor clouds based on spectral line broadening. Under the nearest neighbor approximation, it is possible to analytically express the full width at half maximum as a function of the perturber number density. On the basis of these relations and spectroscopic constants of atomic emission lines of Fe I at 381.58 nm and Ca I at 646.26 nm, quadratic Stark broadening is the dominant broadening mechanism if the degree of ionization exceeds 1%. Resonance broadening and van der Waals broadening should be considered if the degree of ionization is less than 1%. Taking into account the appropriate broadening mechanisms, it is possible to accurately measure the pressure in vapor clouds. We conducted laser ablation experiments using the proposed pressure measurement method in combination with the Boltzmann plot method for temperature. The obtained pressures and temperatures are consistent with an adiabatic expansion. This strongly suggests that the proposed method can measure pressure of vapor clouds accurately. Because thermodynamic quantities can be determined when both pressure and temperature are known, the proposed method enables a complete thermodynamic description of vapor clouds, thereby serving as a powerful tool in investigating the thermodynamic and chemical properties of impact- and laser-induced vapor clouds. Copyright 2010 by the American Geophysical Union.2010, Journal of Geophysical Research E: Planets, 115(10) (10), English[Refereed]Scientific journal
- The vibrational state of chemically reacting CN radicals does not necessarily have a Boltzmann distribution because it may be influenced by the chemical reaction leading to the formation of the CN radicals. Here, we develop a new method to measure the rotational temperature of chemically reacting nonequilibrium cyanide radicals using the band tails of their emission spectra. Because of the very short relaxation time scales, both the translational and rotational states reach a thermal equilibrium even when the vibrational state does not have a Boltzmann distribution. The method proposed in this study has two advantages. First, it is not sensitively affected by self-absorption. Second, it does not require as high a wavelength resolution as other methods because it uses the overall shape of the tail part of the CN emission bands. Thus, our method is more suitable for high-speed temperature measurements, where a high-wavelength-resolution measurement is difficult to obtain. To investigate the validity of our method, we carried out laser-ablation experiments within an N(2) - H(2)O - CO(2) - Ar gas mixture using graphite targets and measured the rotational temperature of laser-induced CN and C(2) radicals using the proposed method. The rotational temperatures exhibit reasonable trends as functions of time and beam cross sections, strongly suggesting that our method is useful for transiational-rotational-temperature estimation of chemically reacting nonequilibrium CN radicals.AMER INST AERONAUT ASTRONAUT, Jul. 2009, JOURNAL OF THERMOPHYSICS AND HEAT TRANSFER, 23(3) (3), 463 - 472, English[Refereed]Scientific journal
- Shock-induced devolatilization in hypervelocity impacts has been considered to play important roles in the atmospheric evolution and mass extinctions in Earth's history. Although the chemical composition of shock-induced gas species from carbonate rocks has been considered as a key to understand the environmental change after the Chicxulub impact, it has not been investigated extensively before. Here, we conduct direct measurements of the chemical composition (CO/CO(2)) of shock-induced gas species from calcite (CaCO(3)) using both a laser gun system and an isotopic labeling technique. The CO/CO(2) ratio of the shock-induced gas species from calcite is measured to be 2.02 +/- 0.41, suggesting that gaseous CO has been dominant in the shock-induced gases in the Chicxulub impact. In order to evaluate the environmental effects of the injection of CO gas, we investigated the post-impact atmospheric chemistry by incorporating our experimental results into a tropospheric photochemical model. The results suggest that an intense (2-5 degrees C) global warming would have lasted for several years after a Chicxulub-size impact mainly due to the greenhouse effect of tropospheric O(3), which is produced via photochemical reactions associated with CO gas. Such an intense global warming could have damaged the biosphere in the mass extinction at the Cretaceous-Paleogene (K-P) boundary. (C) 2009 Elsevier B.V. All rights reserved.ELSEVIER SCIENCE BV, May 2009, EARTH AND PLANETARY SCIENCE LETTERS, 282(1-4) (1-4), 56 - 64, English[Refereed]Scientific journal
- Projectile acceleration and impact experiments using a high-power laser : Impacts with a velocity higher than 10km/s大阪大学レーザーエネルギー学研究センターの高出力レーザーを使ってマクロサイズ(0.1mm以上)の弾丸飛翔体を加速する実験を行っている.これまでに直径0.1〜0.3mmの弾丸飛翔体が秒速10〜60kmに加速されている.この高速度に加速された弾丸飛翔体を使って金属どうしの衝突実験を行い,クレーター,放出破片による二次クレーター,衝突により発生したガスからの輝線,などを観測した.惑星科学への応用を念頭に置いた,珪酸塩物質の衝突発光観測,岩石ターゲットを使ったクレーター形成実験,エアロジェルによる岩石放出破片の捕獲,などの実験も並行して進行中である.日本惑星科学会, Mar. 2009, Planetary people, 18(1) (1), 4 - 9, Japanese[Refereed]
- The farside gravity field of the Moon is improved from the tracking data of the Selenological and Engineering Explorer (SELENE) via a relay subsatellite. The new gravity field model reveals that the farside has negative anomaly rings unlike positive anomalies on the nearside. Several basins have large central gravity highs, likely due to super-isostatic, dynamic uplift of the mantle. Other basins with highs are associated with mare fill, implying basalt eruption facilitated by developed faults. Basin topography and mantle uplift on the farside are supported by a rigid lithosphere, whereas basins on the nearside deformed substantially with eruption. Variable styles of compensation on the near- and farsides suggest that reheating and weakening of the lithosphere on the nearside was more extensive than previously considered.AMER ASSOC ADVANCEMENT SCIENCE, Feb. 2009, SCIENCE, 323(5916) (5916), 900 - 905, English[Refereed]Scientific journal
- Impact velocity of meteorites on planetary and satellite surfaces at the final stage of planetary accretion becomes more than 10 km/s. The impacts with velocities higher than 10 km/s generate very large craters and a large amount of silicate vapor, melt, and fast ejecta, and would make great effects on the planetary surface environments. However, the details of the effects by such impacts on the environments have not been understood well yet. The reasons are probably that macroscopic (> similar to 0.1 mm) projectiles are not easily accelerated to more than 10 km/s in laboratories. This makes it difficult to investigate experimentally the impact phenomenon with impact velocities higher than 10 km/s. In this paper, we demonstrate that higher impact velocities than 10 km/s can be achieved using projectiles with a diameter of 0.1 - 0.3 mm: we accelerate glass and aluminum projectiles using a high-power laser, GEKKO XII - HIPER. The projectiles are collided into LiF targets. We observe some lines of Li gas using a time-resolved spectrometer after an estimated impact time, which indicates that the impact vaporization with higher velocities than 10 km/s occurs.AMER INST PHYSICS, 2009, SHOCK COMPRESSION OF CONDENSED MATTER - 2009, PTS 1 AND 2, 1195, 875 - +, English[Refereed]International conference proceedings
- On the basis of the gravity model of the Moon developed by SELENE (Kaguya), we propose new classification and compensation mechanism of lunar impact basins. Impact basins on lunar far side and limb are classified into Type I and II basins depending on the magnitude of central gravity high in free-air and Bouguer gravity anomalies. Among previously known gravity anomalies, most typical mascons are referred as primary mascon basins. Topographic depression and rim of both Type I and II basins show good correlation between topography and free-air gravity anomaly suggesting elastic support of lunar lithosphere. Central gravity high of Type I basin is inferred to be a result of mantle uplift at the time of basin formation, and is elastically supported, too. On the other hand, free-air anomalies at the center of Type II basins are lower than Bouguer anomalies indicating brittle deformation of the basins. Topographic depression and rim of primary mascon basins on near side of the Moon show little to no free-air gravity anomalies. This indicates a result of elastic relaxation that occurred probably after eruption of mare basalts. Plateau-like signature of gravity anomalies of primary mascon basins implies viscous relaxation at crust-mantle boundary beneath the basins and significant heat (or volatile) transport by basaltic magma.The Geodetic Society of Japan, 2009, Journal of the Geodetic Society of Japan, 55(2) (2), 291 - 305, Japanese[Refereed]
- A New View of Impact Degassing Based on Laser Gun Experiments衝突脱ガス現象は大気の形成やその後の表層環境の進化に大きな影響を与えたと考えられている.我々は,反射衝撃波や封圧の影響を受けずに衝突脱ガス生成気体を回収できる,レーザー銃を用いた衝突脱ガス実験の新しい手法を開発した.炭酸塩岩,硫酸塩岩へ適用した結果,多くの先行研究よりも弱い衝撃波,特に圧縮状態での脱ガスに必要な衝撃圧と比べると数分の一程度と非京に低い衝撃圧で衝突脱ガスが開始することがわかった.これは,比較的低い衝撃圧の条件では圧力解放過程での脱ガス反応が重要であること,天然の衝突でも衝撃圧縮された後圧力が低圧まで開放される領域ではこれまで考えられてきたよりも衝突脱ガスが起こりやすいことを示唆する.日本惑星科学会, Jun. 2008, Planetary people, 17(2) (2), 98 - 104, Japanese[Refereed]
- 初期分析「石」分析チームではリュウグウのミリメータサイズのサンプル（探査機が2回目のタッチダウンで採集した最大サンプルを含む17粒子）を日米欧の放射光施設，ミュオン施設などを利用し物質分析を行った[1]．その結果，リュウグウ母天体の原始惑星系円盤内での形成位置，集積物質の岩石鉱物学的情報，集積した氷の種類，天体内部での水との反応による化学進化，天体衝突の影響について知見が得られた．リュウグウサンプルには，水岩石反応の進行度が異なる物質が混在していることが判明した．リュウグウサンプルの物性（破壊強度，熱拡散係数，比熱，密度など）を実測した．この実測値を使って，リュウグウ母天体形成後の天体内部の加熱による温度経時変化，および衝突破壊プロセスの数値シミュレーションを行い，リュウグウの形成進化を再現した．The Japanese Society for Planetary Sciences, Sep. 2023, Planetary People - The Japanese Society for Planetary Sciences, 32(3) (3), 226 - 235, Japanese
- 様々な研究分野においてそうであるのと同様に，惑星科学の研究の中でも「見積もり」と呼ばれる技術（あるいは操作）は極めて重要な役割をもつ．このたび遊星人では「見積もり」をテーマにした新連載を開始する運びとなった．連載開始に先立ち，連載の内容に関連した座談会が有志によって行われた．この記事では去る7月に行われた座談会の様子をお届けすることで新連載の知名度向上を図り，連載初回記事の露払いとなることを目指す．The Japanese Society for Planetary Sciences, Sep. 2023, Planetary People - The Japanese Society for Planetary Sciences, 32(3) (3), 244 - 259, Japanese
- The Japanese Society for Planetary Sciences, Jun. 2023, Planetary People - The Japanese Society for Planetary Sciences, 32(2) (2), 142 - 149, Japanese
- 粉体標的の衝突直下点近傍の温度分布令和4年度宇宙科学に関する室内実験シンポジウム（2023年3月6日-7日. オンライン開催) 2023 Symposium on Laboratory Experiment for Space Science (March 6-7, 2023. Online Meeting) 資料番号:SA6000187030 レポート番号: 30宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS), Mar. 2023, 令和4 年度宇宙科学に関する室内実験シンポジウム講演集 = Proceedings of 2023 Symposium on Laboratory Experiment for Space Science, Japanese
- 衝突残留磁化強度の温度・圧力依存性に関する研究令和4年度宇宙科学に関する室内実験シンポジウム（2023年3月6日-7日. オンライン開催) 2023 Symposium on Laboratory Experiment for Space Science (March 6-7, 2023. Online Meeting) 資料番号:SA6000187031 レポート番号: 31宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS), Mar. 2023, 令和4 年度宇宙科学に関する室内実験シンポジウム講演集 = Proceedings of 2023 Symposium on Laboratory Experiment for Space Science, Japanese
- 2023, 衝撃波シンポジウム講演論文集(CD-ROM), 2022Shock recovery of rocky materials with decaying compressive pulses: The conditions required for producing shock metamorphic features
- 2023, 日本惑星科学会秋季講演会予稿集(Web), 2023Pattern in ejecta curtain generated by the impact into granular targets of various sized particles
- 種々の粉体への衝突実験: 飛散の様相と凝集物の特性令和3年度宇宙科学に関する室内実験シンポジウム（2022年2月28日-3月1日. オンライン開催) 2022 Symposium on Laboratory Experiment for Space Science (February 28-March 1, 2022. Online Meeting) 資料番号: SA6000178029 レポート番号: 29宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS), Feb. 2022, 令和3年度宇宙科学に関する室内実験シンポジウム 講演集 = Proceedings of 2022 Symposium on Laboratory Experiment for Space Science, Japanese
- 2022, 日本地球惑星科学連合大会予稿集(Web), 2022Shock recovery with decaying compressive pulses: Shock effects in marble, granite, and basalt
- 粉体をはじめとする複雑媒体中の衝撃波伝播時の運動量, エネルギー輸送過程はまだ良くわかっていない. これは異なる密度やサイズを持つ鉱物粒子と空隙で構成されている隕石母天体にそのまま当てはまる. 我々は粉体への衝突実験で爆心点周辺物質を回収する方法を開発した.GEOCHEMICAL SOCIETY OF JAPAN, 2022, Abstracts of Annual Meeting of the Geochemical Society of Japan, 69, 181, Japanese
- The Japanese Society for Planetary Sciences, 25 Sep. 2021, Planetary People - The Japanese Society for Planetary Sciences, 30(3) (3), 112 - 115, Japanese
- ポリイミド膜と圧電性PZTを利用した衝突弾性波型ダストセンサー : 5年間の研究のまとめ令和2年度宇宙科学に関する室内実験シンポジウム（2021年3月5日. オンライン開催)資料番号: SA6000161007レポート番号: 7宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS), Mar. 2021, 令和2年度宇宙科学に関する室内実験シンポジウム 講演集 = Proceedings of 2021 Symposium on Laboratory Experiment for Space Science, Japanese
- 2021, 日本地球惑星科学連合大会予稿集(Web), 2021Elasto-plastic behavior of carbonate rocks under high strain rate deformation
- 2021, 日本惑星科学会秋季講演会予稿集(Web), 2021リュウグウ模擬物質を用いた衝撃回収実験
- 2021, 日本惑星科学会秋季講演会予稿集(Web), 2021天体衝突時の塑性変形加熱が隕石の同位体時計に与える影響
- 2021, 日本惑星科学会秋季講演会予稿集(Web), 2021減衰衝撃波を利用した花崗岩の衝撃回収実験:石英中のFeather Featuresの形成圧力
- 2021, 日本惑星科学会秋季講演会予稿集(Web), 2021リュウグウの衝突乾燥説の実験的検証
- 2018年から2019年にかけて行われたはやぶさ2のリモセン探査により, リュウグウは揮発性成分に乏しく, 半乾き状態であることが明らかとなった. その揮発性成分の少なさを説明する有力仮説は3つあり, そのうちの1つは過去の天体衝突加熱によって揮発性成分を失ったとする「衝突乾燥説」である. 我々は以前リュウグウ模擬試料を用いた衝撃脱ガス実験とそれに対応する数値衝突計算を実施し, 衝撃脱ガス効率は低く, 小惑星帯における典型的な衝突速度程度の衝撃加熱ではリュウグウの乾きを説明することができないことを報告した. 今回はその実験結果を元に炭素質小惑星様物質の脱ガス機構を考察した.GEOCHEMICAL SOCIETY OF JAPAN, 2021, 日本地球化学会年会要旨集(Web), 68th, 79, Japanese
- 2021, 日本惑星科学会秋季講演会予稿集(Web), 2021弾丸アスペクト比がクレーター形状に与える影響
- 衝突雷発生可能性の検証に向けた種々の粉体への衝突実験令和元年度宇宙科学に関する室内実験シンポジウムは、新型コロナウイルスの感染拡大防止のため開催中止。すべて書面発表になりました。 資料番号: SA6000149013 レポート番号: 13宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS), Mar. 2020, 令和元年度宇宙科学に関する室内実験シンポジウム 講演集 = Proceedings of 2020 Symposium on Laboratory Experiment for Space Science, Japanese
- 衝突残留磁化の磁化構造に関する研究令和元年度宇宙科学に関する室内実験シンポジウムは、新型コロナウイルスの感染拡大防止のため開催中止。すべて書面発表になりました。 資料番号: SA6000149012 レポート番号: 12宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS), Mar. 2020, 令和元年度宇宙科学に関する室内実験シンポジウム 講演集 = Proceedings of 2020 Symposium on Laboratory Experiment for Space Science, Japanese
- Large sensitive area dust sensor utilizing a polyimide film and piezoelectric elements令和元年度宇宙科学に関する室内実験シンポジウムは、新型コロナウイルスの感染拡大防止のため開催中止。すべて書面発表になりました。資料番号: SA6000149005レポート番号: 5Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS), Mar. 2020, 令和元年度宇宙科学に関する室内実験シンポジウム 講演集 = Proceedings of 2020 Symposium on Laboratory Experiment for Space Science, Japanese
- 2020, 日本地球惑星科学連合大会予稿集(Web), 2020Modeling pattern formation in ejecta curtains by numerical and laboratory experiments
- 2020, 日本地球惑星科学連合大会予稿集(Web), 2020Impact-driven volatile loss from C-type chondrite-like materials
- 2020, 日本惑星科学会秋季講演会予稿集(Web), 20203次元衝撃回収実験によるコンドライト隕石の衝撃変成度の見直しに向けて
- 2020, 日本惑星科学会秋季講演会予稿集(Web), 2020弾丸形状が重力支配域クレータ形状に与える影響
- We conducted a series of shock devolatilization experiments by using a carbonaceous asteroid analog. We have developed a novel experimental method to investigate the chemical composition of produced gases and the mass of each species quantitatively.GEOCHEMICAL SOCIETY OF JAPAN, 2020, 日本地球化学会年会要旨集(Web), 67th, 94, Japanese
- 2020, 日本鉱物科学会年会講演要旨(Web), 20203D shock recovery experiments for plastic deformation heating during shock metamorphism
- 2020, 日本惑星科学会秋季講演会予稿集(Web), 2020粉体衝突実験における衝突直下点物質の回収
- 2020, 日本惑星科学会秋季講演会予稿集(Web), 2020放出物カーテン内での粒子のクラスター形成:解析モデルと室内実験・数値計算との比較
- 粉体への衝突実験で発生する光点の特徴平成30年度宇宙科学に関する室内実験シンポジウム (2019年2月28日-3月1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 2019 Symposium on Laboratory Experiment for Space Science (February 28 - March 1, 2019. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan 資料番号: SA6000139022宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS), Feb. 2019, 平成30年度宇宙科学に関する室内実験シンポジウム 講演集 = Proceedings of 2019 Symposium on Laboratory Experiment for Space Science, Japanese
- Large sensitive area dust sensor utilizing polyimide film and piezoelectric element2019 Symposium on Laboratory Experiment for Space Science (February 28 - March 1, 2019. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa JapanInstitute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS), Feb. 2019, 平成30年度宇宙科学に関する室内実験シンポジウム 講演集 = Proceedings of 2019 Symposium on Laboratory Experiment for Space Science, Japanese
- 2019, 日本惑星科学会秋季講演会予稿集(Web), 2019Effect of subsurface ice layer on acceleration of Martian meteorites
- 2019, 日本惑星科学会秋季講演会予稿集(Web), 2019Impact heating in oblique impacts with rocks including material strength
- The Geological Society of Japan, 2019, Annual Meeting of the Geological Society of Japan, 126th, 298, Japanese
- 2019, 宇宙科学技術連合講演会講演集(CD-ROM), 63rdMicrobial Contamination Probability Analysis for Martian Moons and Planetary Protection Categorization for Martian Moons Exploration (MMX)
- 衝突によって放出される粉体のパターンとクレーターレイ平成29年度宇宙科学に関する室内実験シンポジウム (2018年2月26日-27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 2018 Symposium on Laboratory Experiment for Space Science (February 26-27, 2018. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan 資料番号: SA6000123009宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS), Feb. 2018, 平成29年度宇宙科学に関する室内実験シンポジウム 講演集 = Proceedings of 2018 Symposium on Laboratory Experiment for Space Science, Japanese
- 球面にできる強度支配域クレーターの形成メカニズム平成29年度宇宙科学に関する室内実験シンポジウム (2018年2月26日-27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 2018 Symposium on Laboratory Experiment for Space Science (February 26-27, 2018. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan 資料番号: SA6000123044宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS), Feb. 2018, 平成29年度宇宙科学に関する室内実験シンポジウム 講演集 = Proceedings of 2018 Symposium on Laboratory Experiment for Space Science, Japanese
- 衝突雷の検証に向けた粉体への高速度衝突平成29年度宇宙科学に関する室内実験シンポジウム (2018年2月26日-27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 2018 Symposium on Laboratory Experiment for Space Science (February 26-27, 2018. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan 資料番号: SA6000123005宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS), Feb. 2018, 平成29年度宇宙科学に関する室内実験シンポジウム 講演集 = Proceedings of 2018 Symposium on Laboratory Experiment for Space Science, Japanese
- Large sensitive area dust sensor utilizing polyimide film and piezoelectric element2018 Symposium on Laboratory Experiment for Space Science (February 26-27, 2018. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa JapanInstitute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS), Feb. 2018, 平成29年度宇宙科学に関する室内実験シンポジウム 講演集 = Proceedings of 2018 Symposium on Laboratory Experiment for Space Science, Japanese
- 2018, 日本惑星科学会秋季講演会予稿集(Web), 2018天体衝突による火星物質の放出過程について
- 2018, 宇宙科学技術連合講演会講演集(CD-ROM), 62ndDevelopment of a dust detector using polyimide film and piezoelectric sensor
- 2018, 日本惑星科学会秋季講演会予稿集(Web), 2018粉体実験及びN体計算による放出物カーテン中での粒子衝突の研究
- 2018, 宇宙科学技術連合講演会講演集(CD-ROM), 62ndFilm Dust Sensor for CubeSat to Observe Cosmic Dusts and Space Debris
- 2018, 日本惑星科学会秋季講演会予稿集(Web), 2018火星衛星フォボスとデイモス II:火星からの質量輸送について
- 2018, 日本惑星科学会秋季講演会予稿集(Web), 2018火星圏物質輸送 II:衛星上の火星物質分布と滅菌
- 石膏球面にできる強度支配域衝突クレーターの形状測定報告平成28年度宇宙科学に関する室内実験シンポジウム (2017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 2017 Symposium on Laboratory Experiment for Space Science (February 27-28, 2017. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan 資料番号: SA6000095030宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS), Feb. 2017, 平成28年度宇宙科学に関する室内実験シンポジウム 講演集 = Proceedings of 2017 Symposium on Laboratory Experiment for Space Science, Japanese
- Feb. 2017, JapanesePreliminary report on shock remanent magnetization measurement
- Large sensitive area dust sensor utilizing polyimide film and piezoelectric element2017 Symposium on Laboratory Experiment for Space Science (February 27-28, 2017. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa JapanInstitute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS), Feb. 2017, 平成28年度宇宙科学に関する室内実験シンポジウム 講演集 = Proceedings of 2017 Symposium on Laboratory Experiment for Space Science, Japanese
- 三鷹 : 日本天文学会, 20 Jan. 2017, 天文月報, 110(2) (2), 105‐110 - 110, JapaneseMaterial Ejection during Hypervelocity Impacts
- 天体衝突は地球史において、生物の大量絶滅をふくむ表層環境の変動を引き起こしてきた。最近黒澤(2016, 地球化学)は、高速度(>30 km/s)で天体衝突が起きた場合、岩石惑星の主要構成要素である珪酸塩が分解され、分子酸素が発生する可能性があることを指摘した。もし実際に、過去の天体衝突に伴って大気・海洋の酸化がおきたことが明らかにされれば、地球の酸化史の描像が刷新される可能性がある。しかしこの新しい仮説について、地質記録に基づく検証は試みられていない。西オーストラリア・ピルバラ地塊には後期太古代の堆積岩が厚く累重するが、その中には天体衝突を示すスフェリュール層が複数挟まれている。発表者らは、その内の一つを含むピルバラ地塊東部のCarawine Dolomiteについて、上述の仮説の検証を目的として層序学的研究を行ってきた。本発表では、この結果について報告する。The Geological Society of Japan, 2017, Annual Meeting of the Geological Society of Japan, 2017, 299, Japanese
- Hypervelocity impacts on the early Earth during the heavy bombardment period are expected to lead unique chemical reactions, which have never been driven on the mean reaction fields on the Earth. The quantitative determinations of injection fluxes of various chemical species on the surface environment is necessary to understand how the chemical evolutions had proceed on the early Earth. We also expect that signatures of such impacts might be fixed in impact-related stratifications as unique geochemical products, such as the spherule beds. We are developing a new experimental system to explore the nature of impact-induced chemical reactions using a two-stage light gas gun. The new system allows us to investigate the final gas products in an open system after hypervelocity impacts at ranged from 1 km/s to 7 km/s. We will present the experimental results with water ice and calcite targets at the conference. We can accelerate any projectile with 2 mm in diameter and shoot onto targets with any chemical compositions and can measure final gas products with the proposed method.GEOCHEMICAL SOCIETY OF JAPAN, 2017, Abstracts of Annual Meeting of the Geochemical Society of Japan, 64, 257, Japanese
- 2017, 日本惑星科学会秋季講演会予稿集(Web), 2017火星衛星探査機(MMX)搭載火星周回ダスト観測装置
- 2017, 日本惑星科学会秋季講演会予稿集(Web), 2017無隔膜開放系における衝突蒸発実験手法の確立
- 2017, 日本惑星科学会秋季講演会予稿集(Web), 2017衝撃圧力分布から推定する重力支配クレータサイズ
- 2017, 日本地球惑星科学連合大会予稿集(Web), 2017球標的へのクレーター形成実験:標的の曲率がクレーター効率に与える影響
- 東京 : 日本航空宇宙学会, Sep. 2016, 宇宙科学技術連合講演会講演集, 60, 5p, Japaneseポリイミド膜と圧電素子を利用した大面積ダストセンサーの開発—Dust detector with large sensitive area using polyimide film and piezoelectric pick-up sensor
- 水氷の開放系衝突蒸発実験平成27年度宇宙科学に関する室内実験シンポジウム (2016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 2016 Symposium on Laboratory Experiment for Space Science (July 23-24, 2016. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan 資料番号: SA6000055007宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS), Feb. 2016, 平成27年度宇宙科学に関する室内実験シンポジウム 講演集 = Proceedings of 2016 Symposium on Laboratory Experiment for Space Science, Japanese
- 石膏球面にできる衝突クレーターに関する実験報告平成27年度宇宙科学に関する室内実験シンポジウム (2016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 2016 Symposium on Laboratory Experiment for Space Science (July 23-24, 2016. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan 資料番号: SA6000055032宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS), Feb. 2016, 平成27年度宇宙科学に関する室内実験シンポジウム 講演集 = Proceedings of 2016 Symposium on Laboratory Experiment for Space Science, Japanese
- ポリイミド膜と圧電素子を利用した大面積センサーの開発平成27年度宇宙科学に関する室内実験シンポジウム (2016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, 神奈川県資料番号: SA6000055045宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS), Feb. 2016, 平成27年度宇宙科学に関する室内実験シンポジウム 講演集 = Proceedings of 2016 Symposium on Laboratory Experiment for Space Science, Japanese
- 2016, 日本惑星科学会秋季講演会予稿集(Web), 2016Generation of reductive carbon compounds by “low“ hypervelocity impacts
- 2016, 日本地球惑星科学連合大会予稿集(Web), 2016衝突点近傍から放出されるイジェクタ速度とその質量:フォボスへの火星物質の輸送
- 2016, 日本惑星科学会秋季講演会予稿集(Web), 2016石膏球面にできる衝突クレーターからのエジェクタ破片放出過程に関する実験的研究
- 2016, 大阪大学レーザーエネルギー学研究センター共同利用・共同研究成果報告書, 2015造岩鉱物の衝激蒸発過程のその場観察:珪酸塩の状態方程式確立に向けて
- 2016, 高圧討論会講演要旨集, 57thレーザー衝撃圧縮下における分子性液体の物性計測
- 2016, 高圧討論会講演要旨集, 57th超高温高圧下のSynthetic Uranusに関する時間分解分光観測
- 衝突放出物の超高速撮像計測—Ultra-high-speed imaging of impact ejecta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宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS), Jul. 2015, 第48回月・惑星シンポジウム = Proceedings of the 48th ISAS Lunar and Planetary Symposium, Japanese
- 数値衝突計算による衝撃圧力減衰過程の再評価—A re-evaluation of shock attenuation using a shock physics code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: SA6000045008宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS), Jul. 2015, 第48回月・惑星シンポジウム = Proceedings of the 48th ISAS Lunar and Planetary Symposium, Japanese
- The Physical Society of Japan, 2015, Meeting Abstracts of the Physical Society of Japan, 70.1, 801, Japanese
- 2015, 日本惑星科学会秋季講演会予稿集(Web), 2015衝突放出物の最大速度とその量:火星物質輸送への応用
- 2015, 日本惑星科学会秋季講演会予稿集(Web), 2015海洋への天体衝突:水蒸気発生量
- 2015, 日本惑星科学会秋季講演会予稿集(Web), 2015水氷の高速衝突蒸発実験
- The Japan Society of Applied Physics, 2015, JSAP Annual Meetings Extended Abstracts, 62nd, 58 - 58, Japanese
- 2015, 日本地球惑星科学連合大会予稿集(Web), 2015石膏球面にできる衝突クレーターの形状
- 2015, 大阪大学レーザーエネルギー学研究センター共同利用・共同研究成果報告書, 2014造岩鉱物の衝撃蒸発過程のその場観察:珪酸塩の状態方程式確立に向けて
- 日本惑星科学会, 10 Sep. 2014, 日本惑星科学会秋期講演会予稿集, 2014, "O6 - 03", JapaneseO6-03 隕石重爆撃期における大気散逸による火星大気と表層水の進化(口頭発表セッション6 表層進化・物質I,口頭発表)
- 日本惑星科学会, 10 Sep. 2014, 日本惑星科学会秋期講演会予稿集, 2014, "O7 - 05", JapaneseO7-05 TIRによるSCIクレータ検出方法の検討 : クレータの熱進化モデル(口頭発表セッショ7 はやぶさ2,口頭発表)
- 日本惑星科学会, 10 Sep. 2014, 日本惑星科学会秋期講演会予稿集, 2014, "O6 - 02", JapaneseO6-02 隕石重爆撃による原始金星の乾燥(口頭発表セッション6 表層進化・物質I,口頭発表)
- 日本惑星科学会, 10 Sep. 2014, 日本惑星科学会秋期講演会予稿集, 2014, "O13 - 03", JapaneseO13-03 流星観測衛星S-CUBEのミッション紹介と開発進捗報告(口頭発表セッション13 ダスト・探査I,口頭発表)
- Institute of Space and Astronautical Science, JAXA ; [2006]-, 05 Aug. 2014, Proceedings of the ISAS Lunar and Planetary Symposium, 46, 7p, JapaneseHigh-speed imaging observations during hypervelocity oblique impacts : The fate of impactor
- 不規則形状衝突体による小惑星表面の掘削過程の数値衝突計算—Numerical modeling of the excavation processes on minor bodies by irregularly-shaped projectiles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: SA6000033023宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS), Aug. 2014, 第47回月・惑星シンポジウム = Proceedings of the 47th ISAS Lunar and Planetary Symposium, Japanese
- The Physical Society of Japan (JPS), 05 Mar. 2014, Meeting abstracts of the Physical Society of Japan, 69(1) (1), 280 - 280, Japanese
- iSALE shock physics codeは惑星科学者に対して公開されている汎用性の高い衝突計算コードである.我々は日本の衝突コミュニテイでもiSALEを自由に扱い,研究を進められる環境を整備するために「iSALE users group in Japan」というグループを立ち上げた.本稿ではiSALEについての簡単な解説を行い,幾つかの計算例を示す.衝突現象は惑星科学の至るところで重要になってくる素過程である.自らの手で数値衝突計算を行えるようになれば,研究の幅が大きく広がることが期待できる.本稿がiSALEでどんなことができるのか想像するための一助となれば幸いである.The Japanese Society for Planetary Sciences, 2014, Planetary People, 23(2) (2), 103 - 110, Japanese
- 約6600万年前（白亜紀末）の生物大量絶滅は、巨大隕石の衝突により引き起こされたと考えられている。しかし、天体衝突が引き起こした環境変動と大量絶滅の具体的なメカニズムは全く決着がついておらず、様々な仮説が乱立している。重要な鍵となるのは、海洋での絶滅記録、特に海洋プランクトンの絶滅の理解であるが、これまでに提案されている絶滅機構の仮説では、地質記録に残る海洋生物の絶滅を説明することは非常に困難であった。本研究では、大阪大学の高出力レーザーを用い、世界初となる宇宙速度での衝突蒸発・ガス分析実験に成功した。実験結果から、先行研究で想定されていた二酸化硫黄ではなく、短期間で硫酸になる三酸化硫黄が隕石衝突で放出されることがわかった。さらに理論計算を行ったところ、衝突で放出された三酸化硫黄は数日以内に酸性雨となって全地球的に降ることと、その結果起こる深刻な海洋酸性化が明らかになった。GEOCHEMICAL SOCIETY OF JAPAN, 2014, Abstracts of Annual Meeting of the Geochemical Society of Japan, 61, 205, Japanese
- 2014, スペース・プラズマ研究会・講演集(Web), 2013大気との相互作用による硫酸塩岩衝突放出物の蒸発に関する実験的研究
- 2014, スペース・プラズマ研究会・講演集(Web), 2013斜め天体衝突の衝撃蒸発過程の撮像・分光・生成ガス同時計測
- 2014, 大阪大学レーザーエネルギー学研究センター共同利用・共同研究成果報告書, 2013隕石衝突による高密度プラズマの生成:惑星大気進化への応用
- 2014, スペース・プラズマ研究会・講演集(Web), 2013「はやぶさ2」SCIの地上較正実験
- 2014, スペースガード研究, 6, Japanese流星観測キューブサットS-CUBE (S3: Shootingstar Sensing Satellite)[Refereed]
- Shock-induced devolatilization of volatile-bearing minerals has played an important role in the formation of the atmosphere and evolution of surface environments of terrestrial planets. The dependence of the degree of devolatilization on ambient pressure has not been investigated in detail before, even though ambient pressure dramatically affects the degree of devolatilization. In this study, we conducted shock recovery experiments on calcite (CaCO3) using newly designed sample containers for released gas analysis, and assessed the dependence of the degree of devolatilization on the partial pressure of CO2. Our results clearly show that the degree of devolatilization increases as the sample container volume increases and the initial mass of calcite decreases.IOP PUBLISHING LTD, 2014, 18TH APS-SCCM AND 24TH AIRAPT, PTS 1-19, 500(PART 6) (PART 6), English[Refereed]
- 日本惑星科学会, 20 Nov. 2013, 日本惑星科学会秋期講演会予稿集, 2013, "O8 - 07", JapaneseO8-07 斜め衝突時の衝撃圧縮段階の超高速撮像観測(口頭発表セッション8(衝突),口頭発表)
- 日本惑星科学会, 20 Nov. 2013, 日本惑星科学会秋期講演会予稿集, 2013, "O8 - 11", JapaneseO8-11 炭素質隕石の衝突蒸発 : 室内実験の結果と引き起こされる環境変動(口頭発表セッション8(衝突),口頭発表)
- 公益社団法人 応用物理学会, 2013, 応用物理学会秋季学術講演会講演予稿集(CD-ROM), 74th, 2577 - 2577, Japanese
- Lately, a Mars Aero-flyby Sample Collection (MASC) mission has been proposed at Japan Aerospace Exploration Agency (JAXA). For the purpose of improving the feasibility of MASC, the development of a sampling system during flying in the Martian dusty atmosphere and the optimization of its system for sampling conditions are crucial. In this work, we have developed three types of sample collectors: (1) silica aerogel (SA), (2) carbon aerogel (CA), (3) a two-layered carbon aerogel and silica aerogel (CASA). Moreover, a particle extraction system has been developed at JAXA in order to manipulate aerogels and particles smaller than 10 μm. The performance of these sample collectors using laboratory models has been investigated by carrying out arcjet heating and light-gas-gun experiments. In consequence, the better heat tolerance of CA has been validated, and thus, the sampling time can be longer than 10 seconds using CA and CASA for the mission. Also, estimated Martian dust particles were successfully captured by the sample collectors, and the particle extraction system has been demonstrated.2013, 5th AIAA Atmospheric and Space Environments Conference[Refereed]
- 2013, スペース・プラズマ研究会・講演集(Web), 2012玄武岩標的クレーター形成実験から求められたスケーリング則(衝突クレーター形成に関する強度スケーリング則の再検証)
- 公益社団法人 応用物理学会, 2013, 応用物理学会春季学術講演会講演予稿集(CD-ROM), 60th, 129 - 129, Japanese
- 2013, スペース・プラズマ研究会・講演集(Web), 2012斜め衝突蒸気雲の空力相互作用を伴う下流方向への運動メカニズム
- 2013, プラズマ・核融合学会年会(Web), 30th隕石衝突による高密度プラズマの生成:惑星大気進化への応用
- 2013, スペース・プラズマ研究会・講演集(Web), 2012火星粒子サンプルリターンに向けたエアロゲルサンプルコレクター開発
- 宇宙科学研究所, 2013, 平成24年度スペースプラズマ研究会・講演集, 2012, 29 (4pp), Japanese空隙の大きな始原天体が捕獲する外来ダスト粒子の貫入深さ
- 宇宙科学研究所, 2013, 平成24年度スペースプラズマ研究会・講演集, 2013, 23 (2pp), Japanese堆積岩への斜め衝突クレーター形成実験
- Flyer acceleration technique using high-power lasers has several advantages such as the achieved velocities higher than 10 km/s and non contamination the products generated by impacts. In this study, we show that a high-power laser can achieve flyer velocities higher than 10 km/s up to 60 km/s using spherical projectiles with a diameter of 0.1-0.3 nun We discuss the projectile condition during the flight based on the results of numerical simulations.E D P SCIENCES, 2013, IFSA 2011 - SEVENTH INTERNATIONAL CONFERENCE ON INERTIAL FUSION SCIENCES AND APPLICATIONS, 59, English[Refereed]
- 日本惑星科学会, 24 Oct. 2012, 日本惑星科学会秋期講演会予稿集, 2012, 43 - 43, JapaneseO4-07 高速粒子衝突による高空隙率ターゲットにできるトラック形状 : 弾丸強度と初期動圧との対応(口頭発表セッション4(惑星大気,衝突科学I),口頭発表)
- 日本惑星科学会, 24 Oct. 2012, 日本惑星科学会秋期講演会予稿集, 2012, 87 - 87, JapaneseO10-02 隕石重爆撃期における金星、地球、火星の大気進化(口頭発表セッション10(惑星形成論III,系外惑星),口頭発表)
- The Physical Society of Japan (JPS), 24 Aug. 2012, Meeting abstracts of the Physical Society of Japan, 67(2) (2), 190 - 190, Japanese
- Mar. 2012, 43th LPSC, id. 1782, EnglishCapture of hypervelocity dusts by highly porous small bodies
- The Japanese Society for Planetary Sciences, 2012, Planetary People, 21(1) (1), 74 - 78, Japanese
- A Mars Aero-flyby Sample Collection (MASC) mission has been proposed lately at Japan Aerospace Exploration Agency (JAXA). In order to improve the feasibility of this mission, the development of its sampling system during flying in the Martian dusty atmosphere to capture floating micron-sized dust particles is crucial. Since aerogel has been used as a capturing medium for micrometeoroids and space debris, it is also planned to be used for the MASC mission. In order to utilize aerogel as the capturing medium of hyperve-locity micron-sized dust particles during the Martian atmospheric flight, several unknown effects, such as aerodynamic heating of aerogel, impact on heated aerogel, and thermal alteration of micron-sized particles inside aerogel, need to be clarified. This work attempts to evaluate these effects by carrying out three types of experiments, (1) heating tests of aerogel in an arcjet wind tunnel, (2) two-stage light gas gun dust capture simulations, and (3) Van de Graaff micron-particle capture simulations. Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc.2012, 50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition, English[Refereed]
- 2012, 衝撃波シンポジウム講演論文集, 2011小規模天体衝突で引き起こされる物理化学過程
- 2012, 衝撃波シンポジウム講演論文集, 2011フラッシュX線を用いた石膏への弾丸貫入とクレーター形成過程のその場観察
- 2012, 衝撃波シンポジウム講演論文集, 2011フラッシュX線を用いた空隙率の高い標的中の弾丸減速過程の観察
- 公益社団法人 応用物理学会, 2012, 応用物理学会学術講演会講演予稿集(CD-ROM), 73rd, 3609 - 3609, Japanese
- 2012, スペース・プラズマ研究会・講演集(Web), 2011フラッシュX線による石膏への弾丸貫入とクレーター形成過程のその場観察
- 2012, スペース・プラズマ研究会・講演集(Web), 2011玄武岩標的を用いたクレーター形成実験(衝突クレーター形成に関する強度スケーリング則の再検証)
- 2012, スペース・プラズマ研究会・講演集(Web), 20112段式軽ガス銃を用いた炭酸塩岩の開放系衝突脱ガス実験
- 2012, スペース・プラズマ研究会・講演集(Web), 2011大気との相互作用による硫酸塩岩衝突放出物の蒸発に関する実験的研究
- 2012, スペース・プラズマ研究会・講演集(Web), 2011下流方向に飛び出す斜め衝突蒸気雲の大気中における運動
- 2012, スペース・プラズマ研究会・講演集(Web), 2011ナイロン-ナイロン衝突の超高速度撮影
- A Mars Aero-flyby Sample Collection (MASC) mission has been proposed in a Mars exploration project at Japan Aerospace Exploration Agency (JAXA). The MASC vehicle enters the Martian atmosphere, captures dust particles and atmospheric gases at sampling altitudes between 30 and 50 km, and returns back to Earth. In order to improve the feasibility of this project, the development of its sampling system during flying in the Martian dusty atmosphere is crucial. Since silica aerogel has been used as a capturing medium for micrometeoroids and space debris, it is also planned to be used for the MASC mission. However, the capture of hypervelocity micron-size dust particles during the Martian atmospheric flight using aerogel is challenging. The aerogel is exposed to significant aerodynamic heating during sampling, and thus, the effect of heated aerogel on the dust particles must be evaluated. This work attempts to evaluate the impact on aerogel and the survivability of the dust particles inside the capturing medium by carrying out light gas gun and Van de Graaff experimental tests. By comparing the cases between normal and heated aerogels, the survivability of the dust samples as well as the heating effect has been investigated.THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, 2012, TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, SPACE TECHNOLOGY JAPAN, 10(28) (28), Pk_11 - Pk_17, English
- 2012, スペース・プラズマ研究会・講演集(Web), 2011火星ダストサンプルリターンに向けたエアロゲル撃ち込み試験検討
- 一般社団法人 日本物理学会, 2012, Meeting Abstracts of the Physical Society of Japan, 67(0) (0), 829 - 829, Japanese
- 日本惑星科学会, 23 Oct. 2011, 日本惑星科学会秋期講演会予稿集, 2011, 145 - 145, JapaneseS34-05P 隕石への超高速衝突実験と塵回収(一般ポスターセッション3,ポスター発表)
- 日本惑星科学会, 23 Oct. 2011, 日本惑星科学会秋期講演会予稿集, 2011, 89 - 89, JapaneseS34-06 空隙の大きな小天体へのダスト衝突 : ダスト破壊と貫入深さとの関係(口頭セッション34:太陽系における衝突科学,口頭発表)
- 日本惑星科学会, 23 Oct. 2011, 日本惑星科学会秋期講演会予稿集, 2011, 92 - 92, JapaneseS34-09 衝撃圧縮による珪酸塩の電離 : 珪酸塩の状態方程式の確立に向けて(口頭セッション34:太陽系における衝突科学,口頭発表)
- 2011, 衝撃波シンポジウム講演論文集, 2010秒速10km以上での衝突による発光:X線計測
- 2011, 高速度イメージングとフォトニクスに関する総合シンポジウム論文集, 2011衝撃圧縮による珪酸塩の電離:月形成巨大衝突への応用
- 2011, スペース・プラズマ研究会・講演集(Web), 2010斜め衝突蒸気雲の内部状態高速撮像/分光観測
- 2011, スペース・プラズマ研究会・講演集(Web), 20102段式軽ガス銃を用いた開放系気相化学分析-天体衝突によるHCN生成-
- 2011, スペース・プラズマ研究会・講演集(Web), 2010火星無着陸サンプルリターンに向けたエアロゲルサンプルキャプチャ検討
- 日本惑星科学会, Dec. 2010, 遊・星・人, 19(4) (4), 356 - 358, JapaneseNew Face 黒澤耕介
- An Outlook for Progress in Hypervelocity Impact Physics Driven by Laser Gun Technology惑星の起源と初期進化には小天体衝突が重要な役割を果たしたと考えられている.しかし,天体衝突に伴う超高温高圧条件下での岩石の蒸発やイオン化の過程は,未解明のままであり,惑星初期進化の理解にとって大きな障害となっている.近年に開発が進んでいるレーザー銃を用いた超高速衝突実験技術は,岩石の衝突蒸発・イオン化過程をその場観察することを可能にする.本章では,レーザー銃が拓く天体衝突物理学の展望を解説する.プラズマ・核融合学会, 25 Oct. 2010, Journal of plasma and fusion research, 86(10) (10), 589 - 593, Japanese
- 11 Oct. 2010, 高圧討論会講演集, 51, 275 - 275, JapaneseFlyer acceleration using a high-power laser : Impact experiments at 10-60km/s
- 11 Oct. 2010, 高圧討論会講演集, 51, 267 - 267, JapaneseThermodynamic evolution of shock-heated silicates due to >10km/s impacts
- 302 衝突蒸気雲の膨張過程における電子の役割(オーラルセッション7 衝突・破壊過程)惑星形成最終期においては、天体同士の衝突速度が10km/sを超え、内部惑星の主要構成要素であるケイ酸塩でさえも蒸発することが理論的、実験的に示されている[Ahrens & O'keefe, 1972; Kurosawa et al., Submitted]。我々は大阪大学レーザーエネルギー学研究センターに設置された大型レーザー「激光XII号」を用いてケイ酸塩の衝撃圧縮実験を行い、衝撃圧縮-断熱膨張の熱力学進化を計測してきた。その結果、電離/電子再結合による発熱/吸熱が蒸気雲の進化に重要な役割を果たし得ることが明らかとなってきた[Kurosawa et al., 2010]。本講演ではこの結果を受けて、電子挙動がケイ酸塩蒸気雲の時間進化に与える影響を示し、その重要性を指摘する。先行研究で、化学結合はそのエネルギーが小さいために、蒸気雲の膨張過程に影響を与えないことが示されている[Melosh, 2007]が、電離エネルギーは非常に大きいので,電離/電子再結合が蒸気雲の膨張過程に影響を与える可能性がある。具体的には電子励起、電離を考慮した一様な蒸気雲の膨張モデルを構築し、(1)蒸気雲の膨張速度(音速),(2)蒸気雲の冷却率が電離を考慮することによって、どの程度変化するか評価した。その結果、電離を考慮すると、(1)蒸気雲の膨張が遅くなるために、凝縮相の放出物が長時間加速を受け続けること、(2)蒸気雲の冷却率が桁で減少することが明らかとなった。前者は、月形成巨大衝突後の放出物挙動を変化させ得る可能性を示唆し、電離過程を考慮した巨大衝突流体計算の必要性を指摘する。後者は蒸気雲の化学反応生成物、特に微量成分(HCNなどの生命前駆物質)や低温安定成分(SO_3など)の生成量推定にはまだ不定性が残っている可能性を示唆する結果である。日本惑星科学会, 06 Oct. 2010, 日本惑星科学会秋期講演会予稿集, 2010, 53 - 53, Japanese
- 日本惑星科学会, 06 Oct. 2010, 日本惑星科学会秋期講演会予稿集, 2010, 93 - 93, JapaneseP013 高出力レーザーによる飛翔体の加速と衝突実験 : 可視高速カメラおよびX線カメラによる衝突光の撮影(ポスターセッション2)
- 日本惑星科学会, 06 Oct. 2010, 日本惑星科学会秋期講演会予稿集, 2010, 54 - 54, Japanese303 激光XII号を用いた衝突蒸気雲内の硫黄酸化物の化学組成測定(オーラルセッション7 衝突・破壊過程)
- 2010, Proceedings of Lunar and Planetary Science Confe rence XXXXIRoles of shock-induced ionization due to >10km/s impacts on evolution of silicate vaporclouds
- 2010, スペース・プラズマ研究会, 2009(CD-ROM)小規模天体衝突によるHCN合成
- 2010, 宇宙科学技術連合講演会講演集(CD-ROM), 54th火星無着陸サンプルリターンミッションにおけるダストサンプル検討
- 2010, Proc. Lunar Planet. Sci. Conf., 41st, # (CD-ROM)E ects of Laser Energy on LIBS Spectra
- 2009, Proceedings of 42th ISAS Lunar and Planetary Symposium (印刷中(掲載確定))Spectroscopic observations on CN radical production process due to oblique impacts : Thermodynamic states of impact- and laser-induced CN radicals
- Report : Meeting "Physics of Impact Process of Solar System Bodies IV"記事種別: 会議・学会報告・シンポジウムThe Japanese Society for Planetary Sciences, 25 Dec. 2008, Planetary people, 17(4) (4), 247 - 251, Japanese
- 日本惑星科学会, 01 Nov. 2008, 日本惑星科学会秋期講演会予稿集, 2008, 51 - 51, Japanese217 発光輝線形状解析によるレーザー生成蒸気雲の圧力測定(衝突現象および関連室内実験,オーラルセッション6)
- The Japanese Society for Planetary Sciences, 01 Nov. 2008, Abstracts Fall Meeting of the Japanese Society for Planetary Sciences, 2008, 124 - 124, EnglishP204 Far side gravity field of the Moon from four-way Doppler measurements of SELENE (Kaguya)
- 216 高速度衝突蒸発現象の発光分光観測 : シリケイト蒸気の発生(衝突現象および関連室内実験,オーラルセッション6)秒速10km/sを超える速度の天体衝突が起きた場合,惑星及び衝突天体物質を構成するケイ酸塩も蒸発すると言われている[e.g., Ahrens & O'keefe, 1972]。ケイ酸塩蒸気の発生は月形成過程や衝突蒸気雲内での化学反応を議論する上で極めて重要な問題である[e.g., Pahleven & Stevenson, 2007]。しかし実験の困難さのため,今まで秒速10km/sを超える高速度衝突実験は行われていない。宇宙速度での衝突が起こると,衝突直下点のケイ酸塩は>100GPa,>10^4Kという超高温高圧の熱力学状態に達すると予想される。しかし,そのような高温高圧のケイ酸塩の物性データは揃っておらず,実際にどのような熱力学に達するかは未解明である。従って実際にケイ酸塩試料への宇宙速度衝突実験を行い,ケイ酸塩の蒸発を確認し,衝撃加熱温度を実測する必要がある。我々は阪大レーザー研にある高出力レーザー,激光12号を用いて,金属箔(Ta,厚さ:50μm,密度:16.6g/cc)を〜10km/sまで加速し,代表的なケイ酸塩鉱物(Forsterite, Diopside, Quartz)への高速度衝突実験を行っている。弾丸に密度の大きいTaを用いているのでケイ酸塩同士が衝突した場合よりも高い衝撃圧を達成することができる(ケイ酸塩同士の衝突では〜15km/sの衝突に対応)。今回は第一ステップとして超強力な閃光を捉え,発光スペクトルを取得する光学系の構築とケイ酸塩蒸気の発生を確認することを目的とした。長時間露光分光器(露光時間:1秒)を用いて標的背面から発光分光観測を行った。透明な鉱物試料を用いているため,標的背面からでも,衝突直下点からの発光を捉えることができる。その結果Diopsideへの衝突の場合,Caの輝線が確認された。このことはDiopsideが衝突によって蒸発したことを強く示唆している。今後,より高時間,高波長分解能を持つ分光器で発光スペクトルを取得し,宇宙速度衝突の際のケイ酸塩の熱力学状態を推定する予定である。日本惑星科学会, 01 Nov. 2008, 日本惑星科学会秋期講演会予稿集, 2008, 50 - 50, Japanese
- 2008, 衝撃波シンポジウム講演論文集, 2007レーザー生成CNの分子並進-分子回転温度推定法について
- 落下塔実験施設を用いたクレーター形成実験We 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. 資料番号: AA0063349049宇宙航空研究開発機構宇宙科学研究本部, Mar. 2007, 宇宙利用シンポジウム, 23rd, 182 - 184, Japanese
- Meteorite impacts on the Earth induce the release of a huge amount of climatically active gases from the impacting body and crustal material under very high temperature and pressure condition. Here, we focused on the impact-induced degassing from carbonate minerals which is abundant on the Earth. Previous researches have assumed that impact-induced gas from carbonate is wholly CO2 [e.g. O'Keefe and Ahrens, 1989]. However, there is a prospect that the gas from carbonate contains CO which is stable under high temperature. The release of CO and its atmospheric chemical reactions may cause the increase of tropospheric ozone which has intensive greenhouse effect. Hence, when we consider the climatic effects caused by impact-induced gases from carbonate, it is very crucial problem whether the gas is CO or CO2. Now we conducted the impact-degassing experiments using a laser gun and specified the molecular species of impact-induced gas from carbonate.THE JAPANESE SOCIETY FOR PLANETARY SCIENCES, 2007, Abstracts for fall meeting of the Japanese Society for Planetary Science, 2007f, 48 - 48
- Devolatilization from rock caused by hypervelocity impacts is believed to have played important roles on early atmosphere formation and the evolution of surface environments of terrestrial planets. In order to apply the results of laboratory experiments to planetary scale impacts, we need to understand detailed physical and chemical process and to establish the scaling law of impact-induced devolatilization. In this talk, we show the result of shock recovery experiment using calcite. The result suggests that the devolatilization from calcite occurs during the release of pressure.THE JAPANESE SOCIETY FOR PLANETARY SCIENCES, 2007, Abstracts for fall meeting of the Japanese Society for Planetary Science, 2007, 49 - 49
- We conducted laser ablation experiments in model atmospheres to simulate chemical reactions between impact-generated CN radicals and an ambient atmosphere. We investigated the dependence of atmospheric composition on the yield of HCN.THE JAPANESE SOCIETY FOR PLANETARY SCIENCES, 2006, Abstracts for fall meeting of the Japanese Society for Planetary Science, 2006f, 64 - 64
- Impact 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.THE JAPANESE SOCIETY FOR PLANETARY SCIENCES, 2006, Abstracts for fall meeting of the Japanese Society for Planetary Science, 2006(0) (0), 26 - 26
- We performed a long-term photometric observation to monitor changes in near-infrared light flux of 9P/Tempel 1 induced by the NASA Deep Impact event. Our observation covered three different bands (J band: 1.2 micron, H band: 1.6 micron, K band: 2.1 micron) from June 27 to July 28 using the 1.4m IRSF Telescope in South Africa with SIRIUS (Simultaneous-3color InfraRed Imager for Unbiased Survey) and the 105cm Schmidt Telescope at Kiso Observatory with KONIC (Kiso Observatory Near Infrared Camera). This study is based mainly on the data obtained with SIRIUS because there is little data obtained at Kiso due to bad weather. We will report the changes in the magnitude and colors of comet coma during a month, and the changes in dust production rate.THE JAPANESE SOCIETY FOR PLANETARY SCIENCES, 2005, Abstracts for fall meeting of the Japanese Society for Planetary Science, 2005f, 126 - 126
- 56th Lunar and Planetary Science Conference, Mar. 2025, EnglishRole of carbon in chondrite matrix during impact heatingPoster presentation
- 宇宙科学に関わる室内実験シンポジウム, Feb. 2025, Japanese方解石砂を用いた完全解放系衝撃回収実験Oral presentation
- 宇宙科学に関わる室内実験シンポジウム, Feb. 2025, Japanese金属容器を用いた衝突磁化の実験的研究Oral presentation
- 第20会衝突研究会, Nov. 2024, Japanese改良Zモデルを用いた運動量輸送効率の推定: 楕円標的の場合Poster presentation
- 第20会衝突研究会, Nov. 2024, Japanese隕石の衝撃変成度2分性の成因Poster presentation
- 第20会衝突研究会, Nov. 2024, Japanese鉱物の衝撃変成分類指標作成についての新展開Oral presentation
- 日本惑星科学会秋季講演会, Sep. 2024, Japanese隕石の衝撃変成度2分性の成因Oral presentation
- 日本惑星科学会秋季講演会, Sep. 2024, Japaneseはやぶさ2分離カメラ画像を用いたSCI衝突イジェクタの非対称分布復元Oral presentation
- 宇宙開発•産業化に関するシンポジウム「宇宙建設」, Jul. 2024, Japanese天体衝突による破砕, 掘削の物理と月面の表面撹拌[Invited]Invited oral presentation
- Hera Community Meeting, Apr. 2024, EnglishEjecta deposition on Dimorphos after the DART impactOral presentation
- 55th Lunar and Planetary Science Conference, Mar. 2024, EnglishEjecta deposition on Dimorphos after the DART impactOral presentation
- 宇宙科学に関わる室内実験シンポジウム, Feb. 2024, Japanese粉体標的の衝突点近傍物質の無飛散回収Oral presentation
- Hera-JP online meeting, Jan. 2024, Japanese改良Z modelを用いたDART衝突後のDidymos, Dimorphos表面の堆積厚み分布推定Oral presentation
- 第19会衝突研究会, Oct. 2023, Japanese衝撃波後面でのダスト衝突によるコンドリュールの破壊Oral presentation
- 第19会衝突研究会, Oct. 2023, Japanese改良Z modelを用いたDART衝突後のDimorphos表面の堆積厚の見積もりOral presentation
- HiPeR symposium, Nov. 2021, JapaneseResponse of planetary materials against impact shocks[Invited]Invited oral presentation
- 地球惑星科学連合大会, Jun. 2021, Japanese炭酸塩岩の高歪速度変形時の挙動[Invited]Invited oral presentation
- JpGU-AGU Joint meeting, Jul. 2020, EnglishAn overlooked heat source in impact events and its effect on the degree of devolatilization of natural calcite carbonates[Invited]Invited oral presentation
- 天文シミュレーションプロジェクトユーザーズミーティング, Jan. 2020, JapaneseImpact simulations by using iSALE shock physics code: Its applications to planetary sciences[Invited]Invited oral presentation
- 惑星保護標準ワークショップ, Sep. 2019, Japanese惑星検疫: 火星衛星の事例[Invited]Invited oral presentation
- Committee on the Review of Planetary Protection Requirements for Sample Return from Phobos and Deimos, Sep. 2018, EnglishAssessment of microbial contamination probability for sample return from Martian moons[Invited]Invited oral presentation
- JpGU, May 2018, English, Domestic conferenceThe roles of hypervelocity impacts on the surface evolution of the Hadean Earth[Invited]Invited oral presentation
- The 4th ELSI International Symposium, Jan. 2016, English, International conferenceAn atmospheric response against from impact bombardments on Earth and Venus: The role of impact ejecta[Invited]Invited oral presentation
- 太陽圏シンポジウム, Mar. 2015, Japanese, Domestic conference衝突有機岩石プラズマの可視光分光診断: 惑星初期進化への応用[Invited]Invited oral presentation
- 月科学研究会, Oct. 2014, Japanese, Domestic conference月探査から探る隕石重爆撃[Invited]Invited oral presentation
- The 10th international conference on High Energy Density Laboratory Astrophysics, May 2014, English, International conferenceThe thermodynamic response of silicate minerals after meteoritic impacts: Implications for the evolution of planetary atmospheres[Invited]Invited oral presentation
- 12th Workshop on Fine Particle Plasmas National Institute for Fusion Science, Nov. 2011, English, International conferenceTime-resolved spectroscopic observations of shock-induced silicate ionization and electron recombination[Invited]Invited oral presentation
- 日本地球惑星科学連合大会, May 2010, Japanese, Domestic conference宇宙速度衝突によるケイ酸塩の電離の役割[Invited]Invited oral presentation
- International Workshop on Warm Dense Matter, Mar. 2009, English, International conferenceSpectroscopic observations of a liquid-vapor phase change of silicate in the warm dense matter region[Invited]Invited oral presentation
- Japanese Society for Origins of Life and AstrobiologyApr. 2025 - Present
- 生命の起原および進化学会Sep. 2020 - Mar. 2025
- THE GEOCHEMICAL SOCIETY OF JAPAN
- THE JAPANESE SOCIETY FOR PLANETARY SCIENCES
- 公益財団法人ひょうご科学技術協会, 学術研究助成, 神戸大学, Apr. 2024 - Mar. 2025, Principal investigator隕石に残る衝撃変成度2分性:初期太陽系の軌道力学環境復元
- 日本学術振興会, 科学研究費助成事業, 挑戦的研究(萌芽), 千葉工業大学, Jul. 2021 - Mar. 2024, Principal investigator超高速度衝突の爆心地: 極限環境経験物質の無飛散回収宇宙科学研究所 超高速衝突実験施設にて種々の粉体試料に対して衝突速度, 弾丸材質を変化させた高速度衝突実験を実施した(黒澤, 佐藤, 新原, 富岡). 本研究課題の申請段階では密度が大きい粉体試料を使用したときのみ衝突点近傍の試料が「おわん形状組織」として「凍結」されることがわかっていた. その後の系統的な実験により, 通常の砂であってもおわん形状組織を回収し, 詳細分析を実施可能であることがわかってきた. これは惑星科学応用を検討する上で重要である. 従来用いていたジルコンビーズは工業製品であり, その製法から天然には存在し得ない結晶構造をしていることは明らかであった. このような物質を用いた実験では最終的に研究成果を論文にまとめる際に潜在的問題となることは明らかであった. 2021年度の実験により隕石に含まれているような鉱物を主体とする砂でもおわん形状組織を回収できることが明らかになり, 惑星科学上重要な造岩鉱物が衝突直下点で経験する変成を明らかにする目処がたったことになる. 長石砂を標的として行った実験で回収したおわん形状組織を電子顕微鏡で観察したところ, 秒速3 kmほどの衝突速度においても熔融したような組織が形成されていることを確かめた. 理想媒体を想定した衝突物理学計算では長石はこの程度の衝突速度で発生する熱では熔融し得ないことから実在物質中では従来想定していなかった局所的なエネルギー集中が起きることが明らかとなった. 典型的な造岩鉱物から作成したおわん形状組織はそのような過程を凍結した媒体として期待できることを改めて確かめることができた.
- 日本学術振興会, 科学研究費助成事業, 基盤研究(B), 東京大学, Apr. 2021 - Mar. 2024, Coinvestigator衝突残留磁化を用いて探る惑星磁場の初期進化史本研究では，実験により衝突残留磁化強度分布モデルを構築し，そのモデルを使って，地球型惑星の衝突盆地上空で人工衛星により観測された惑星磁場強度記録を読み解き，地球型惑星の磁場強度進化を復元する．そのために研究期間内に，（１）衝突残留磁化着磁実験，（２）衝突実験試料の残留磁化分布測定，（３）衝突磁化強度分布モデルの作成，（４）衝突盆地上空での人工衛星による磁場観測データ取得・解析，を実施する．そして項目３と４の成果を合わせて，（５）衝突イベント時の古惑星磁場強度を復元する，という研究計画である．2021年度までの研究において，以下の成果が得られている．細粒なチタン磁鉄鉱を含む玄武岩試料を用いて衝突磁化着磁実験および回収試料の細分化・残留磁化測定を行い，衝突残留磁化の残留磁化強度および残留磁化安定性が衝突点からの距離に応じて系統的な変化をする事が確認された（上記項目１と２に対応）．衝突計算コードを用いて衝突実験時に玄武岩試料が経験した温度・圧力変化を計算して磁気測定の結果と比較する事で，衝突残留磁化と温度・圧力変化の対応関係を得ることに成功した（Sato et al. 2021, GRLで成果報告）．予察的な解析から，衝突残留磁化強度を衝撃波伝搬時の温度・圧力変化の関数として表現できる可能が示された（項目３に対応）．人工衛星による磁場観測データとして，月（かぐや，LP），火星（MGS，MAVEN），水星（MESSENGER）の磁場観測データを解析用に取得し，クレーター周辺での衝突残留磁化の痕跡を検討するための解析環境の整備を行った（項目４に対応）．
- 日本学術振興会, 科学研究費助成事業, 基盤研究(A), 千葉工業大学, Apr. 2019 - Mar. 2023, Principal investigator隕石に刻まれた初期太陽系衝突史の復元2020年度までに確立した3次元衝撃回収実験手法を用いて系統的な実験(黒澤, 新原, 松井, 科研費雇用博士研究員)を行った. 試料が経験した温度圧力は数値衝突計算で評価する手順を確立した(黒澤, 玄田). 手始めに地球の岩石である大理石, 玄武岩, 花崗岩の衝撃応答を詳細に観察した(新原, 三河内, 小池, 鹿山, 佐野, 科研費雇用博士研究員).その過程で独国フンボルト博物館のChristopher Hamann博士との共同研究体制を築くことができた. 現在までに(1)炭酸塩鉱物(Calcite)は>3 GPaの衝撃で波状消光を示すこと, (2)花崗岩, 玄武岩中の衝撃変成は概ね既存の衝撃変成指標であるStoffler tableによる分類と一致すること, (3) 花崗岩中で8-18 GPaでFeather featuresと呼ばれる組織が形成されること, (3)花崗岩中では10-20 GPaで脈状の高圧相鉱物及び熔融ガラス組織が形成すること, (4)玄武岩中では~10 GPaで熔融ガラスの脈が形成すること, を明らかにすることができた. 地球の岩石にも隕石と同種の鉱物が含まれているので, これらの結果は隕石中鉱物にも適用可能であろう. 特に炭酸塩鉱物は小惑星リュウグウの試料に含まれていたことから, 衝撃指標として早速応用できる可能性がある. (1)の結果は国際誌に投稿済み, その他の成果は投稿準備中である.
また本研究課題の目玉であった試料の事前加熱装置を用いた衝撃回収実験手法も確立しつつある. 初期温度を上げた衝撃回収実験は実験的な困難から世界的にもデータに乏しいため, 世界に先駆けた成果を挙げることができると期待される.
実際の隕石分析でも成果があった. 研究チームで手に入れた未分類隕石の各種分析を行い基本的な記載を行った(新原, 三河内). この隕石はEL-melt rock NWA 14248として国際隕石学会に登録された. - Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Fund for the Promotion of Joint International Research (Fostering Joint International Research (B)), Oct. 2018 - Mar. 2023, CoinvestigatorEstimation of location, magnitude, and mode of the impact of a small solar system body in Southeast Asia at ca. 0.8 Ma and its effect on the surrounding environment2021年度に入ってもコロナ感染の波は繰り返し、べトナムでも日本とは位相がずれた形で感染の波が繰り返された。ベトナムへの渡航は一応可能となったものの、県をまたいだ移動が制限されていたため、ベトナム南部調査が実施出来ぬまま年度末を迎えた。ベトナム南部におけるイジェクタの層厚、粒度、組成のデータの取得は決定的に重要なため、計画の1年延長を申請して認められた。 ベトナム調査の延期に伴い、イジェクタ堆積物試料の分析や実験を集中して行う様に計画を変更した。特に、国際誌に投稿した原稿に対して、我々が報告した衝撃変成石英が、これまで知られている衝撃変成石英といくつか特徴が異なることが指摘された。我々はこれが衝突の標的となった岩石が多孔質な砂岩だったためではないかと考え、黒澤、多田賢弘に依頼して花崗岩および多孔質砂岩を使った衝突実験を行った。回収試料の薄片の偏光顕微鏡やSEMでのPlanar deformation features(PDFs)の比較観察から、典型的衝撃変成石英のPDFsと異なる特徴のいくつかは、標的が多孔質砂岩であったことに起因する可能性が示唆され、さらに観察を進めている。また、多田賢弘、鹿山らは、放射光XRDを使って推定衝突地点周辺の基盤をなす中生代砂岩中の石英の格子定数を測定し、その値が推定衝突地点に向かって増加する傾向を見いだし、現在その確認を行っている。 上総層群におけるマイクロテクタイト検出については、岡田が中心となり、銚子での掘削コア Choshi-1 について昨年度5cm間隔で採取した試料の粗粒シルトサイズ以上の粒度画分を抽出して検鏡作業を行うと共に、養老川ルートにおける国本層のMIS20付近の層準についてシルト岩部分のサンプリングを行い、先ずマイクロテクタイト層準を絞り込むための詳細な酸素同位体層序構築のため有孔虫の抽出作業を行った。
- 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), 千葉工業大学, Apr. 2018 - Mar. 2020, Principal investigator室内・数値衝突実験による氷天体衝突時のエネルギー分配・化学反応過程の解明二段式水素ガス銃は, 惑星科学における重要素過程である天体衝突現象を調べる上で理想的な加速器の一つである. 2019年度までで二段式水素ガス銃を用いつつ, 銃由来の化学汚染を極力抑える実験手法を確立し, 衝突で発生するガス成分の気相化学分析を行う手順を確立した. 2020年度はこの成果を論文としてまとめ, 国際誌に報告した. 本手法をC型小惑星構成物質模擬試料を用いた衝撃脱ガス実験に適用した. C型小惑星は内側太陽系への水と有機物の主要な運び手であると考えられており, その起源と進化を探るべく, はやぶさ2, OSIRIS-RExといった小惑星探査の対象天体となっている. これらの探査からわかってきたことはC型小惑星であるリュウグウ, Bennuはその歴史を通じて様々な衝突現象を経験したこと, リュウグウはその歴史のどこかの時点で加熱を受け, 揮発性成分の大部分を失っていることである. そこでC型小惑星に内包される揮発性成分の衝撃に対する安定性を調べるべく, 系統的な衝撃実験を実施した. その結果, 衝撃によって放出される気体の主要成分はCO2であり, 小惑星帯における典型的な衝突速度の条件では衝突体質量の0.1 wt%程度の揮発性成分放出しか起こらないことが明らかとなった. 本研究の結果はリュウグウが揮発性成分を失った理由の一つとして挙げられている, 「リュウグウ母天体への多数の天体衝突による加熱説」を強く否定するものである. また実験の結果, 硫黄含有ガスの放出がほとんど起こらないことも明らかになった. これは天体衝突直下点の物質のS/C比が上昇することを意味する. 2020年末に地球に帰還するはやぶさ2がもたらすリュウグウからの回収試料を分析する際に天体衝突の痕跡を探す指標として有用であると期待される.
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Challenging Research (Exploratory), Chiba Institute of Technology, Jun. 2017 - Mar. 2020, Principal investigatorImpact-induced lightning: A new perspective on the paleoenvironment of planetsImpact-generated ejecta curtains produced by hypervelocity impacts onto planets are investigated using experimental, analytical and numerical methods. It is found that no large-scale discharge structures are generated in typical spatial and time scales of laboratory impact experiments. The analytic and numerical models were developed to analysis the mutual collisions between the constituent micro particles of ejecta curtains. We have reproduced the mesh-like patterns of ejecta curtains observed in the laboratory experiments. In the future, we will investigate the possibility whether lightning discharges occur in ejecta curtain.
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), Tokyo Institute of Technology, Apr. 2017 - Mar. 2020, CoinvestigatorStudy on impact spallation: Material transfer between planetary bodies by impactsWe performed impact simulations and experiments in order to reveal the details of the impact spallation process. We newly found "late-stage acceleration" mechanism, where the lightly shocked surface materials near the impact point are accelerated by the pressure gradient at the root of the ejecta curtain. We also confirmed this mechanism in our impact experiments. This new mechanism can explain the ejection of Martian meteorites, which experienced relatively low peak pressures, from the Martian surface. We applied the impact simulations for the material transfer from the Martian surface to Martian moons, and found that the transferred mass was more than 10 times than previously estimated.
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (A), Japan Agency for Marine-Earth Science and Technology, Apr. 2017 - Mar. 2020, CoinvestigatorNitrogen fluxes and chemical evolution potential in the Hadean Earth addressed by simulated experimentsThis research has pursued the potential fluxes of reduced nitrogen compounds in the Hadean Earth, when the earthly life originated, by means of simulated state-of-art experiments for meteorite impact on ocean, UV irradiation and lightning discharge, and submarine hydrothermal circulations. Based on the data obtained from these newly developed experiments, we have estimated the potential supply fluxes of reduced nitrogen compounds from extraterrestrial and terrestrial sources. Although the significant contribution of extraterrestrial organic matter is not still ruled out, the synthesis of reduced nitrogen compounds in the ocean throughout the processes of lightning (NOx from N2), precipitation in the ocean (NOx accumlation), and hydrithermal circulation (reduced nitrogens from NOx) is the most predominant supply of reduced nitrogen compounds in the Hadean Earth. This implies that deep-sea hydrothermal vents would be the most advantageous for chemical evolution in the Hadean Earth.
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (A), The University of Tokyo, Apr. 2017 - Mar. 2020, CoinvestigatorDevelopment of Ne measurement instrument for ultra-small Mars missionsIn order to measure the neon isotope ratio in the Mars atmosphere with ultra-small spacecraft, we developed orbitrap-type light-weight high-mass-resolution (m/dm > 10,000) mass spectrometer. We also developed membrane system to separate Ne and Ar before taking Mars air into the mass spectrometer. Using the newly developed system, we obtained gas separation performance as a function of time. We also designed a new mechanism to keep high vacuum condition using getter-type pump with very limited resources, such as size, weight, and electricity.
- 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), 千葉工業大学, Apr. 2015 - Mar. 2017, Principal investigator冥王代の天体重爆撃による生命誕生場への電気化学的擾乱本研究は原始地球における生命誕生時期が天体衝突が頻発していた「天体重爆撃期」に重なっていることに着目した. 研究目的は天体衝突が生命誕生場に与える擾乱を定量的に明らかにすることである. 単発の天体衝突で引き起こされる物理化学過程を検討し, 初期数億年間に地球質量のおよそ1%におよぶ天体群が金星・地球・火星に衝突した場合に何が起こるか？を明らかにするために研究を遂行した. 得られた主要な成果を以下に述べる. (1)数値衝突計算コードであるiSALE shock physics codeを計算出力を後処理し, 衝突後の衝突天体が辿る熱力学経路を計算する後解析コードを作成した. マルチコア計算機を導入し, 数値衝突計算と後述の100万回に及ぶ天体衝突を扱う確率論的重爆撃モデル計算を幅広いパラメータ空間を効率よく埋めるための計算環境を構築した. (2)天体衝突時に衝突天体が蒸発することで発生する気相化学種を衝突速度の関数として明らかにした. 特に酸素分子の生成効率が衝突速度に強く依存していることから, 天体衝突による非生物的酸素生成が生命誕生場への新たな自由エネルギー源となり得ることを提唱した. また原始地球や火星に過渡的に酸素を含んだ大気が発生した場合に特殊な地質試料が残される可能性があることから仮説の実証に向けた新たな研究を開始した. (3)天体重爆撃期に頻発した天体衝突の重畳された情報を紐解くため, モンテカルロ法を用いた確率論的重爆撃モデルを構築した. (4)確率論的重爆撃モデルを用いて原始金星の表層変動を解いた. 天体衝突によって発生する大量の細粒岩石と高温の初期金星大気の間の化学反応を検討し, 天体重爆撃が初期金星を極度に乾燥した状態に導いたとする新説を提唱した. 本モデルは火星の大気進化を扱う計算にも流用され, 初期火星の大気全圧下限を制約するという成果を挙げている.
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Challenging Exploratory Research, Chiba Institute of Technology, Apr. 2014 - Mar. 2017, CoinvestigatorLaboratory Simulation of Shooting StarsWhen a mmm-sized dust particle enters into Earth's atmosphere, it is observed as a bright streak, a shooting star. A shooting star is one-time event and, in most cases, the dust is completely vaporized. Thus the original size and composition is not easy to estimate only from ground-based observation. In this study we constructed a laboratory experimental system to simulate shooting stars by using a two-stage light gas gun. In this system the simulated shooting star is observed by high-speed camera with the frame rate of 1 mega frames/s, and simultaneously the light from the shooting star is analysed by a spectrograph with the wavelength resolution of 5.7 nm. Our laboratory experimental system will provide a fundamental data-set which relate the ground-based observational result to the original size and composition of the shooting star.
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Young Scientists (B), Chiba Institute of Technology, Apr. 2013 - Mar. 2016, Principal investigatorAn experimental study on the decomposition of organic matters in the early solar system by impact-generated super critical waterWe constructed a new experimental system to investigate the processes of shock vaporization and subsequent chemical reactions in an open system using targets including water ice. A new experimental chamber with a cooling stage down to 170 K and with a quadruple mass spectrometer was newly made. The chamber was set to the downrange of the two-stage light-gas gun placed at Planetary Exploration Research Center of Chiba Institute of Technology. As the first step of research development, we conducted hypervelocity impact experiments with pure-water-ice targets. We confirmed that impact-generated water vapor can be detected with a high signal-to-noise ratio. The developed experimental procedure is expected to be applied directly to a more complex target material, that is a mixture of water-organics-silicate minerals, with a minor modification.
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (A), Chiba Institute of Technology, Apr. 2012 - Mar. 2015, CoinvestigatorAn experimental study on planetary evolution using a high-power laserThe objective of this study is to determine the Hugoniot curve of forsterite, one of the most important silicates, in the density-pressure-temperature-entropy space. We conducted a series of laser shock experiments using a high power laser and obtained shock-induced radiance and shock velocity in forsterite samples under 400-900 GPa compression. Our results indicate that the degree of vaporization of forsterite after shock compression is much higher than previously thought. Hypervelocity impacts at >30 km/s on the Hadean Earth may produce a transient O2-rich atmosphere. This hypothesis can be tested by the geochemical analyses of impact-related geologic record.
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Research Activity Start-up, Japan Aerospace Exploration Agency, 2011 - 2012, Principal investigatorGas-phase chemical analysis in an open system using a 2-stage light gas gunWe construct an experimental technique of gas-phase chemical analysis in an open system for 2-stage light gas guns to investigate a key parameter, which controls the amount of impact-generated vapor. The amount of impact-generated CO2 from natural calcite blocks was measured under a wide range of peak shock pressure using the proposed method. The obtained CO2 amount as a function of shock pressure is in a good agreement with a theoretical prediction by the entropy method. This result provides the first experimental evidence of the validity of the widely-used entropy method to estimate the amount of impact-generated vapor.
- Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), 2008 - 2011, Coinvestigator not use grantsImpact experiments at higher velocities than 10 km/s and application to the planetary atmosphere formation processWe develop a new flyer acceleration technique using a high-power laser, Gekko XII, at Osaka University, which can accelerate sheet flyers with a diameter of ~ 0.5 mm and a thickness of ~ 30 - 50 .m and spherical projectiles with a diameter of 0.1 - 0.3 mm to velocities higher than 10 km/s up to 60 km/s. Using this technique, we carry out impact experiments to investigate impact vapor and melt, equation of state, craters, and ejecta. Obtained data are quite new and important for various themes in the field of planetary science.
- 日本学術振興会, 科学研究費助成事業, 特別研究員奨励費, 東京大学, 2009 - 2010, Principal investigator高速度衝突天体物質と惑星大気間の化学反応による生命前駆物質生成に関する実験的研究本研究では、天体衝突によって原始無生物地球上に生命前駆物質を供給する可能性について実験的に検証することを目的としている。先行研究から原始地球環境下では、天体衝突による生命前駆物質の合成効率は低く、生体関連分子までの化学進化を起こすのは難しいと考えられている。これは端的には、隕石中には窒素がほとんど含まれていないことが原因である。本研究では衝突天体物質に含まれる炭素と原始地球に豊富に存在したと考えられる窒素が効率よく反応する過程を提唱している。直径1km以下の天体が、低角度斜め衝突を起こした場合、衝突で粉砕された天体が下流側に飛び出し、周辺大気と激しく混合する。この過程は生命前駆物質として最重要物質であるシアノ化合物を効率よく生成できる可能性があるが、複雑な過程であるため、再現実験によるデータをもとにしたモデル化を行うことが求められている。今年度は、宇宙科学研究所の2段式軽ガス銃を利用し、再現実験を行う技術開発を行い、予備的な結果を取得した。従来加速銃を用いた実験では加速ガス、ガンデブリのために生成ガスの化学分析を行うことは困難であったが,これらの化学汚染を極力抑える手法を開発し、ガス分析を行う技術を確立することに成功した。弾丸,標的ともに酸素を含まないプラスチックを用いて、窒素中で衝突を起こした。最終的に生成された気体を簡易ガス検知管で分析したところ,およそ0.1%の蒸発炭素がシアノ化合物に変換されていることがわかった.シアノ化合物は生命起源に最も重要な役割を果たしたと考えられている。今後は実際の隕石試料を標的に用い、シアノ化合物の生成効率を計測する。またパラメータ依存性を調べることで現象のモデル化を行い、実際に原始地球表層環境での天体衝突によるシアノ化合物の合成量を推定していく。