Carbonaceous asteroids, including Ryugu and Bennu, which have been explored by the Hayabusa2 and ... more Carbonaceous 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.
50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 2012
ABSTRACT A Mars Aero-flyby Sample Collection (MASC) mission has been proposed lately at Japan Aer... more ABSTRACT 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 hypervelocity 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.
In order to investigate impact production of carbonaceous products by asteroids on Titan and othe... more 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.
Accurate equation of state (EOS) is essential for understanding a variety of geologic processes a... more 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., MANEOS 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 demand, we derive a new semi-analytical on-Hugoniot EOS, which requires only the Hugoniot shock velocity parameters and specific heat. Comparison with experimental data indicates that this EOS can reproduce on-Hugoniot entropy and temperature of ice and quartz very ...
We present a new pressure measurement method for high-temperature rock vapor plumes using spectra... more We present a new pressure measurement method for high-temperature rock vapor plumes using spectral line broadening. This method may serve as a powerful tool for the understanding of post-impact chemistry.
We conducted dust impact experiments into highly porous brittle targets using a flash X-ray syste... more We conducted dust impact experiments into highly porous brittle targets using a flash X-ray system and showed that the deceleration process of projectiles and the cavity morphology is similar to those reported for aerogel targets.
We conducted laser ablation experiments to investigate whether impact-induced high-temperature CN... more We conducted laser ablation experiments to investigate whether impact-induced high-temperature CN radicals are converted to HCN in a neutral atmosphere. The results indicate that this HCN formation mechanism is more efficient than pure shock heating of a
We conducted laser ablation experiments in redox-neutral gas mixtures using graphite and Murchiso... more We conducted laser ablation experiments in redox-neutral gas mixtures using graphite and Murchison meteorite. The results suggest that CN radicals generated by interactions between impactor material and an atmospheric N2 are fixed into the condensates efficiently.
We conducted laser ablation experiments using graphite targets and redox-neutral atmospheres to i... more We conducted laser ablation experiments using graphite targets and redox-neutral atmospheres to investigate chemical reactions after an oblique impacts on the early Earth. The results indicate that a large amount of HCN may be produced under planetary-scale impacts.
We assess the role of devolatilization of (NH4)2SO4 in Titan's crust by cometary impacts for ... more We assess the role of devolatilization of (NH4)2SO4 in Titan's crust by cometary impacts for the origin of N2 by laboratory experiments. Our results suggest that the N2 production for 4.5 Gyr reaches ~2.5-10 times that in the present atmosphere.
ABSTRACT Accurate equation of state (EOS) is essential for understanding a variety of geologic pr... more ABSTRACT 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 semianalytical on-Hugoniot EOS, which requires only the Hugoniot shock velocity parameters and specific heat, Grüneisen 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.
Origins of life and evolution of the biosphere : the journal of the International Society for the Study of the Origin of Life, Jan 22, 2015
In order to investigate impact production of carbonaceous products by asteroids on Titan and othe... more 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 ...
We present a new experimental method for gas-phase chemical analysis in an open system using a tw... more We present a new experimental method for gas-phase chemical analysis in an open system using a two-stage light gas gun at ISAS/JAXA to investigate the decarbonation pressure of calcite. The "effective" decarbonation pressure of calcite is ~60 GPa,.
Carbonaceous asteroids, including Ryugu and Bennu, which have been explored by the Hayabusa2 and ... more Carbonaceous 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.
50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 2012
ABSTRACT A Mars Aero-flyby Sample Collection (MASC) mission has been proposed lately at Japan Aer... more ABSTRACT 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 hypervelocity 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.
In order to investigate impact production of carbonaceous products by asteroids on Titan and othe... more 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.
Accurate equation of state (EOS) is essential for understanding a variety of geologic processes a... more 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., MANEOS 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 demand, we derive a new semi-analytical on-Hugoniot EOS, which requires only the Hugoniot shock velocity parameters and specific heat. Comparison with experimental data indicates that this EOS can reproduce on-Hugoniot entropy and temperature of ice and quartz very ...
We present a new pressure measurement method for high-temperature rock vapor plumes using spectra... more We present a new pressure measurement method for high-temperature rock vapor plumes using spectral line broadening. This method may serve as a powerful tool for the understanding of post-impact chemistry.
We conducted dust impact experiments into highly porous brittle targets using a flash X-ray syste... more We conducted dust impact experiments into highly porous brittle targets using a flash X-ray system and showed that the deceleration process of projectiles and the cavity morphology is similar to those reported for aerogel targets.
We conducted laser ablation experiments to investigate whether impact-induced high-temperature CN... more We conducted laser ablation experiments to investigate whether impact-induced high-temperature CN radicals are converted to HCN in a neutral atmosphere. The results indicate that this HCN formation mechanism is more efficient than pure shock heating of a
We conducted laser ablation experiments in redox-neutral gas mixtures using graphite and Murchiso... more We conducted laser ablation experiments in redox-neutral gas mixtures using graphite and Murchison meteorite. The results suggest that CN radicals generated by interactions between impactor material and an atmospheric N2 are fixed into the condensates efficiently.
We conducted laser ablation experiments using graphite targets and redox-neutral atmospheres to i... more We conducted laser ablation experiments using graphite targets and redox-neutral atmospheres to investigate chemical reactions after an oblique impacts on the early Earth. The results indicate that a large amount of HCN may be produced under planetary-scale impacts.
We assess the role of devolatilization of (NH4)2SO4 in Titan's crust by cometary impacts for ... more We assess the role of devolatilization of (NH4)2SO4 in Titan's crust by cometary impacts for the origin of N2 by laboratory experiments. Our results suggest that the N2 production for 4.5 Gyr reaches ~2.5-10 times that in the present atmosphere.
ABSTRACT Accurate equation of state (EOS) is essential for understanding a variety of geologic pr... more ABSTRACT 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 semianalytical on-Hugoniot EOS, which requires only the Hugoniot shock velocity parameters and specific heat, Grüneisen 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.
Origins of life and evolution of the biosphere : the journal of the International Society for the Study of the Origin of Life, Jan 22, 2015
In order to investigate impact production of carbonaceous products by asteroids on Titan and othe... more 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 ...
We present a new experimental method for gas-phase chemical analysis in an open system using a tw... more We present a new experimental method for gas-phase chemical analysis in an open system using a two-stage light gas gun at ISAS/JAXA to investigate the decarbonation pressure of calcite. The "effective" decarbonation pressure of calcite is ~60 GPa,.
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