The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
Pascal Rosenblatt - One of the best experts on this subject based on the ideXlab platform.
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On the Impact Origin of Phobos and Deimos. IV. Volatile Depletion
The Astrophysical Journal, 2018Co-Authors: Ryuki Hyodo, Sébastien Charnoz, Hidenori Genda, Francesco Pignatale, Pascal RosenblattAbstract:Recent works have shown that the Martian moons Phobos and Deimos may have accreted within a giant impact-generated disk whose composition is about an equal mixture of Martian material and impactor material. Just after the giant impact, the Martian surface heated up to ∼3000-6000 K and the building blocks of moons, including volatile-rich vapor, were heated up to ∼2000 K. In this paper, we investigate the volatile loss from the building blocks of Phobos and Deimos by hydrodynamic escape of vapor and radiation pressure on condensed particles. We show that a non-negligible amount of volatiles (>10% of the vapor with temperature >1000 K via hydrodynamic escape, and moderately volatile dusts that condense at ∼700-2000 K via radiation pressure) could be removed just after the impact during their first single orbit from their pericenters to apocenters. Our results indicate that bulk Phobos and Deimos are depleted in volatile elements. Together with future explorations such as the Japan Aerospace eXploration Agency's Martian Moons eXploration mission, our results could be used to constrain the origin of Phobos and Deimos.
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On the Impact Origin of Phobos and Deimos IV: Volatile Depletion
The Astrophysical Journal, 2018Co-Authors: Ryuki Hyodo, Sébastien Charnoz, Hidenori Genda, Francesco Pignatale, Pascal RosenblattAbstract:Recent works have shown that Martian moons Phobos and Deimos may have accreted within a giant impact-generated disk whose composition is about an equal mixture of Martian material and impactor material. Just after the giant impact, the Martian surface is heated up to $\sim3000-6000$ K and the building blocks of moons, including volatile-rich vapor, are heated up to $\sim2000$ K. In this paper, we investigate the volatile loss from the building blocks of Phobos and Deimos by hydrodynamic escape of vapor and radiation pressure on condensed particles. We show that a non-negligible amount of volatiles ($> 10\%$ of the vapor with temperature $> 1000$ K via hydrodynamic escape, and moderately volatile dusts that condense at $\sim700-2000$ K via radiation pressure) could be removed just after the impact during their first signle orbit from their pericenters to apocenters. Our results indicate that bulk Phobos and Deimos are depleted in volatile elements. Together with future explorations such as JAXA's MMX (Martian Moons eXploration) mission, our results would be used to constrain the origin of Phobos and Deimos.
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On the Impact Origin of Phobos and Deimos. III. Resulting Composition from Different Impactors
The Astrophysical Journal, 2018Co-Authors: Francesco Pignatale, Pascal Rosenblatt, Sébastien Charnoz, Ryuki Hyodo, Tomoki Nakamura, Hidenori GendaAbstract:The origin of Phobos and Deimos in a giant impact-generated disk is gaining larger attention. Although this scenario has been the subject of many studies, an evaluation of the chemical composition of the Mars's moons in this framework is missing. The chemical composition of Phobos and Deimos is unconstrained. The large uncertainties about the origin of the mid-infrared features; the lack of absorption bands in the visible and near-infrared spectra; and the effects of secondary processes on the moons' surfaces make the determination of their composition very difficult using remote sensing data. Simulations suggest a formation of a disk made of gas and melt with their composition linked to the nature of the impactor and Mars. Using thermodynamic equilibrium, we investigate the composition of dust (condensates from gas) and solids (from a cooling melt) that result from different types of Mars impactors (Mars-, CI-, CV-, EH-, and comet-like). Our calculations show a wide range of possible chemical compositions and noticeable differences between dust and solids, depending on the considered impactors. Assuming that Phobos and Deimos resulted from the accretion and mixing of dust and solids, we find that the derived assemblage (dust-rich in metallic iron, sulfides and/or carbon, and quenched solids rich in silicates) can be compatible with the observations. The JAXA's Martian Moons eXploration (MMX) mission will investigate the physical and chemical properties of Phobos and Deimos, especially sampling from Phobos, before returning to Earth. Our results could be then used to disentangle the origin and chemical composition of the pristine body that hit Mars and suggest guidelines for helping in the analysis of the returned samples.
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Accretion of Phobos and Deimos in an extended debris disc stirred by transient moons
Nature Geoscience, 2016Co-Authors: Pascal Rosenblatt, Sébastien Charnoz, Kevin M. Dunseath, Mariko Terao-dunseath, Antony Trinh, Ryuki Hyodo, Hidenori Genda, Stéven ToupinAbstract:Phobos and Deimos, the two small satellites of Mars, are thought either to be asteroids captured by the planet or to have formed in a disc of debris surrounding Mars following a giant impact. Both scenarios, however, have been unable to account for the current Mars system. Here we use numerical simulations to suggest that Phobos and Deimos accreted from the outer portion of a debris disc formed after a giant impact on Mars. Larger moons are formed from the denser inner disc and migrate outwards due to gravitational interactions with it. The resulting orbital resonances spread outwards and gather the dispersed debris, facilitating accretion into two satellites of sizes similar to Phobos and Deimos. The larger inner moons fall back to Mars after about 5 million years due to the tidal pull of the planet, after which the two outer satellites evolve into Phobos- and Deimos-like orbits. Our results clarify why Mars has two small satellites instead of one large moon. Our model predicts that Phobos and Deimos are composed of a mixture of material from Mars and the impactor.
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Accretion of Phobos and Deimos in an extended debris disc stirred by transient moons
Nature Geoscience, 2016Co-Authors: Pascal Rosenblatt, Sébastien Charnoz, Kevin M. Dunseath, Mariko Terao-dunseath, Antony Trinh, Ryuki Hyodo, Hidenori Genda, Stéven ToupinAbstract:Phobos and Deimos, the two small satellites of Mars, are thought either to be asteroids captured by the planet or to have formed in a disc of debris surrounding Mars following a giant impact^ 1 , 2 , 3 , 4 . Both scenarios, however, have been unable to account for the current Mars system^ 1 , 2 , 3 , 5 , 6 , 7 . Here we use numerical simulations to suggest that Phobos and Deimos accreted from the outer portion of a debris disc formed after a giant impact on Mars. In our simulations, larger moons form from material in the denser inner disc and migrate outwards due to gravitational interactions with the disc. The resulting orbital resonances spread outwards and gather dispersed outer disc debris, facilitating accretion into two satellites of sizes similar to Phobos and Deimos. The larger inner moons fall back to Mars after about 5 million years due to the tidal pull of the planet, after which the two outer satellites evolve into Phobos- and Deimos-like orbits. The proposed scenario can explain why Mars has two small satellites instead of one large moon. Our model predicts that Phobos and Deimos are composed of a mixture of material from Mars and the impactor. Mars has two small moons that may have formed in the aftermath of a giant impact. Simulations suggest that Phobos and Deimos accreted from the disperse outer region of the debris disc that was stirred up by short-lived larger moons.
Hidenori Genda - One of the best experts on this subject based on the ideXlab platform.
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On the Impact Origin of Phobos and Deimos. IV. Volatile Depletion
The Astrophysical Journal, 2018Co-Authors: Ryuki Hyodo, Sébastien Charnoz, Hidenori Genda, Francesco Pignatale, Pascal RosenblattAbstract:Recent works have shown that the Martian moons Phobos and Deimos may have accreted within a giant impact-generated disk whose composition is about an equal mixture of Martian material and impactor material. Just after the giant impact, the Martian surface heated up to ∼3000-6000 K and the building blocks of moons, including volatile-rich vapor, were heated up to ∼2000 K. In this paper, we investigate the volatile loss from the building blocks of Phobos and Deimos by hydrodynamic escape of vapor and radiation pressure on condensed particles. We show that a non-negligible amount of volatiles (>10% of the vapor with temperature >1000 K via hydrodynamic escape, and moderately volatile dusts that condense at ∼700-2000 K via radiation pressure) could be removed just after the impact during their first single orbit from their pericenters to apocenters. Our results indicate that bulk Phobos and Deimos are depleted in volatile elements. Together with future explorations such as the Japan Aerospace eXploration Agency's Martian Moons eXploration mission, our results could be used to constrain the origin of Phobos and Deimos.
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On the Impact Origin of Phobos and Deimos IV: Volatile Depletion
The Astrophysical Journal, 2018Co-Authors: Ryuki Hyodo, Sébastien Charnoz, Hidenori Genda, Francesco Pignatale, Pascal RosenblattAbstract:Recent works have shown that Martian moons Phobos and Deimos may have accreted within a giant impact-generated disk whose composition is about an equal mixture of Martian material and impactor material. Just after the giant impact, the Martian surface is heated up to $\sim3000-6000$ K and the building blocks of moons, including volatile-rich vapor, are heated up to $\sim2000$ K. In this paper, we investigate the volatile loss from the building blocks of Phobos and Deimos by hydrodynamic escape of vapor and radiation pressure on condensed particles. We show that a non-negligible amount of volatiles ($> 10\%$ of the vapor with temperature $> 1000$ K via hydrodynamic escape, and moderately volatile dusts that condense at $\sim700-2000$ K via radiation pressure) could be removed just after the impact during their first signle orbit from their pericenters to apocenters. Our results indicate that bulk Phobos and Deimos are depleted in volatile elements. Together with future explorations such as JAXA's MMX (Martian Moons eXploration) mission, our results would be used to constrain the origin of Phobos and Deimos.
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On the Impact Origin of Phobos and Deimos. III. Resulting Composition from Different Impactors
The Astrophysical Journal, 2018Co-Authors: Francesco Pignatale, Pascal Rosenblatt, Sébastien Charnoz, Ryuki Hyodo, Tomoki Nakamura, Hidenori GendaAbstract:The origin of Phobos and Deimos in a giant impact-generated disk is gaining larger attention. Although this scenario has been the subject of many studies, an evaluation of the chemical composition of the Mars's moons in this framework is missing. The chemical composition of Phobos and Deimos is unconstrained. The large uncertainties about the origin of the mid-infrared features; the lack of absorption bands in the visible and near-infrared spectra; and the effects of secondary processes on the moons' surfaces make the determination of their composition very difficult using remote sensing data. Simulations suggest a formation of a disk made of gas and melt with their composition linked to the nature of the impactor and Mars. Using thermodynamic equilibrium, we investigate the composition of dust (condensates from gas) and solids (from a cooling melt) that result from different types of Mars impactors (Mars-, CI-, CV-, EH-, and comet-like). Our calculations show a wide range of possible chemical compositions and noticeable differences between dust and solids, depending on the considered impactors. Assuming that Phobos and Deimos resulted from the accretion and mixing of dust and solids, we find that the derived assemblage (dust-rich in metallic iron, sulfides and/or carbon, and quenched solids rich in silicates) can be compatible with the observations. The JAXA's Martian Moons eXploration (MMX) mission will investigate the physical and chemical properties of Phobos and Deimos, especially sampling from Phobos, before returning to Earth. Our results could be then used to disentangle the origin and chemical composition of the pristine body that hit Mars and suggest guidelines for helping in the analysis of the returned samples.
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Accretion of Phobos and Deimos in an extended debris disc stirred by transient moons
Nature Geoscience, 2016Co-Authors: Pascal Rosenblatt, Sébastien Charnoz, Kevin M. Dunseath, Mariko Terao-dunseath, Antony Trinh, Ryuki Hyodo, Hidenori Genda, Stéven ToupinAbstract:Phobos and Deimos, the two small satellites of Mars, are thought either to be asteroids captured by the planet or to have formed in a disc of debris surrounding Mars following a giant impact. Both scenarios, however, have been unable to account for the current Mars system. Here we use numerical simulations to suggest that Phobos and Deimos accreted from the outer portion of a debris disc formed after a giant impact on Mars. Larger moons are formed from the denser inner disc and migrate outwards due to gravitational interactions with it. The resulting orbital resonances spread outwards and gather the dispersed debris, facilitating accretion into two satellites of sizes similar to Phobos and Deimos. The larger inner moons fall back to Mars after about 5 million years due to the tidal pull of the planet, after which the two outer satellites evolve into Phobos- and Deimos-like orbits. Our results clarify why Mars has two small satellites instead of one large moon. Our model predicts that Phobos and Deimos are composed of a mixture of material from Mars and the impactor.
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Accretion of Phobos and Deimos in an extended debris disc stirred by transient moons
Nature Geoscience, 2016Co-Authors: Pascal Rosenblatt, Sébastien Charnoz, Kevin M. Dunseath, Mariko Terao-dunseath, Antony Trinh, Ryuki Hyodo, Hidenori Genda, Stéven ToupinAbstract:Phobos and Deimos, the two small satellites of Mars, are thought either to be asteroids captured by the planet or to have formed in a disc of debris surrounding Mars following a giant impact^ 1 , 2 , 3 , 4 . Both scenarios, however, have been unable to account for the current Mars system^ 1 , 2 , 3 , 5 , 6 , 7 . Here we use numerical simulations to suggest that Phobos and Deimos accreted from the outer portion of a debris disc formed after a giant impact on Mars. In our simulations, larger moons form from material in the denser inner disc and migrate outwards due to gravitational interactions with the disc. The resulting orbital resonances spread outwards and gather dispersed outer disc debris, facilitating accretion into two satellites of sizes similar to Phobos and Deimos. The larger inner moons fall back to Mars after about 5 million years due to the tidal pull of the planet, after which the two outer satellites evolve into Phobos- and Deimos-like orbits. The proposed scenario can explain why Mars has two small satellites instead of one large moon. Our model predicts that Phobos and Deimos are composed of a mixture of material from Mars and the impactor. Mars has two small moons that may have formed in the aftermath of a giant impact. Simulations suggest that Phobos and Deimos accreted from the disperse outer region of the debris disc that was stirred up by short-lived larger moons.
Ryuki Hyodo - One of the best experts on this subject based on the ideXlab platform.
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On the Impact Origin of Phobos and Deimos. IV. Volatile Depletion
The Astrophysical Journal, 2018Co-Authors: Ryuki Hyodo, Sébastien Charnoz, Hidenori Genda, Francesco Pignatale, Pascal RosenblattAbstract:Recent works have shown that the Martian moons Phobos and Deimos may have accreted within a giant impact-generated disk whose composition is about an equal mixture of Martian material and impactor material. Just after the giant impact, the Martian surface heated up to ∼3000-6000 K and the building blocks of moons, including volatile-rich vapor, were heated up to ∼2000 K. In this paper, we investigate the volatile loss from the building blocks of Phobos and Deimos by hydrodynamic escape of vapor and radiation pressure on condensed particles. We show that a non-negligible amount of volatiles (>10% of the vapor with temperature >1000 K via hydrodynamic escape, and moderately volatile dusts that condense at ∼700-2000 K via radiation pressure) could be removed just after the impact during their first single orbit from their pericenters to apocenters. Our results indicate that bulk Phobos and Deimos are depleted in volatile elements. Together with future explorations such as the Japan Aerospace eXploration Agency's Martian Moons eXploration mission, our results could be used to constrain the origin of Phobos and Deimos.
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On the Impact Origin of Phobos and Deimos IV: Volatile Depletion
The Astrophysical Journal, 2018Co-Authors: Ryuki Hyodo, Sébastien Charnoz, Hidenori Genda, Francesco Pignatale, Pascal RosenblattAbstract:Recent works have shown that Martian moons Phobos and Deimos may have accreted within a giant impact-generated disk whose composition is about an equal mixture of Martian material and impactor material. Just after the giant impact, the Martian surface is heated up to $\sim3000-6000$ K and the building blocks of moons, including volatile-rich vapor, are heated up to $\sim2000$ K. In this paper, we investigate the volatile loss from the building blocks of Phobos and Deimos by hydrodynamic escape of vapor and radiation pressure on condensed particles. We show that a non-negligible amount of volatiles ($> 10\%$ of the vapor with temperature $> 1000$ K via hydrodynamic escape, and moderately volatile dusts that condense at $\sim700-2000$ K via radiation pressure) could be removed just after the impact during their first signle orbit from their pericenters to apocenters. Our results indicate that bulk Phobos and Deimos are depleted in volatile elements. Together with future explorations such as JAXA's MMX (Martian Moons eXploration) mission, our results would be used to constrain the origin of Phobos and Deimos.
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On the Impact Origin of Phobos and Deimos. III. Resulting Composition from Different Impactors
The Astrophysical Journal, 2018Co-Authors: Francesco Pignatale, Pascal Rosenblatt, Sébastien Charnoz, Ryuki Hyodo, Tomoki Nakamura, Hidenori GendaAbstract:The origin of Phobos and Deimos in a giant impact-generated disk is gaining larger attention. Although this scenario has been the subject of many studies, an evaluation of the chemical composition of the Mars's moons in this framework is missing. The chemical composition of Phobos and Deimos is unconstrained. The large uncertainties about the origin of the mid-infrared features; the lack of absorption bands in the visible and near-infrared spectra; and the effects of secondary processes on the moons' surfaces make the determination of their composition very difficult using remote sensing data. Simulations suggest a formation of a disk made of gas and melt with their composition linked to the nature of the impactor and Mars. Using thermodynamic equilibrium, we investigate the composition of dust (condensates from gas) and solids (from a cooling melt) that result from different types of Mars impactors (Mars-, CI-, CV-, EH-, and comet-like). Our calculations show a wide range of possible chemical compositions and noticeable differences between dust and solids, depending on the considered impactors. Assuming that Phobos and Deimos resulted from the accretion and mixing of dust and solids, we find that the derived assemblage (dust-rich in metallic iron, sulfides and/or carbon, and quenched solids rich in silicates) can be compatible with the observations. The JAXA's Martian Moons eXploration (MMX) mission will investigate the physical and chemical properties of Phobos and Deimos, especially sampling from Phobos, before returning to Earth. Our results could be then used to disentangle the origin and chemical composition of the pristine body that hit Mars and suggest guidelines for helping in the analysis of the returned samples.
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Accretion of Phobos and Deimos in an extended debris disc stirred by transient moons
Nature Geoscience, 2016Co-Authors: Pascal Rosenblatt, Sébastien Charnoz, Kevin M. Dunseath, Mariko Terao-dunseath, Antony Trinh, Ryuki Hyodo, Hidenori Genda, Stéven ToupinAbstract:Phobos and Deimos, the two small satellites of Mars, are thought either to be asteroids captured by the planet or to have formed in a disc of debris surrounding Mars following a giant impact. Both scenarios, however, have been unable to account for the current Mars system. Here we use numerical simulations to suggest that Phobos and Deimos accreted from the outer portion of a debris disc formed after a giant impact on Mars. Larger moons are formed from the denser inner disc and migrate outwards due to gravitational interactions with it. The resulting orbital resonances spread outwards and gather the dispersed debris, facilitating accretion into two satellites of sizes similar to Phobos and Deimos. The larger inner moons fall back to Mars after about 5 million years due to the tidal pull of the planet, after which the two outer satellites evolve into Phobos- and Deimos-like orbits. Our results clarify why Mars has two small satellites instead of one large moon. Our model predicts that Phobos and Deimos are composed of a mixture of material from Mars and the impactor.
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Accretion of Phobos and Deimos in an extended debris disc stirred by transient moons
Nature Geoscience, 2016Co-Authors: Pascal Rosenblatt, Sébastien Charnoz, Kevin M. Dunseath, Mariko Terao-dunseath, Antony Trinh, Ryuki Hyodo, Hidenori Genda, Stéven ToupinAbstract:Phobos and Deimos, the two small satellites of Mars, are thought either to be asteroids captured by the planet or to have formed in a disc of debris surrounding Mars following a giant impact^ 1 , 2 , 3 , 4 . Both scenarios, however, have been unable to account for the current Mars system^ 1 , 2 , 3 , 5 , 6 , 7 . Here we use numerical simulations to suggest that Phobos and Deimos accreted from the outer portion of a debris disc formed after a giant impact on Mars. In our simulations, larger moons form from material in the denser inner disc and migrate outwards due to gravitational interactions with the disc. The resulting orbital resonances spread outwards and gather dispersed outer disc debris, facilitating accretion into two satellites of sizes similar to Phobos and Deimos. The larger inner moons fall back to Mars after about 5 million years due to the tidal pull of the planet, after which the two outer satellites evolve into Phobos- and Deimos-like orbits. The proposed scenario can explain why Mars has two small satellites instead of one large moon. Our model predicts that Phobos and Deimos are composed of a mixture of material from Mars and the impactor. Mars has two small moons that may have formed in the aftermath of a giant impact. Simulations suggest that Phobos and Deimos accreted from the disperse outer region of the debris disc that was stirred up by short-lived larger moons.
Sébastien Charnoz - One of the best experts on this subject based on the ideXlab platform.
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On the Impact Origin of Phobos and Deimos. IV. Volatile Depletion
The Astrophysical Journal, 2018Co-Authors: Ryuki Hyodo, Sébastien Charnoz, Hidenori Genda, Francesco Pignatale, Pascal RosenblattAbstract:Recent works have shown that the Martian moons Phobos and Deimos may have accreted within a giant impact-generated disk whose composition is about an equal mixture of Martian material and impactor material. Just after the giant impact, the Martian surface heated up to ∼3000-6000 K and the building blocks of moons, including volatile-rich vapor, were heated up to ∼2000 K. In this paper, we investigate the volatile loss from the building blocks of Phobos and Deimos by hydrodynamic escape of vapor and radiation pressure on condensed particles. We show that a non-negligible amount of volatiles (>10% of the vapor with temperature >1000 K via hydrodynamic escape, and moderately volatile dusts that condense at ∼700-2000 K via radiation pressure) could be removed just after the impact during their first single orbit from their pericenters to apocenters. Our results indicate that bulk Phobos and Deimos are depleted in volatile elements. Together with future explorations such as the Japan Aerospace eXploration Agency's Martian Moons eXploration mission, our results could be used to constrain the origin of Phobos and Deimos.
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On the Impact Origin of Phobos and Deimos IV: Volatile Depletion
The Astrophysical Journal, 2018Co-Authors: Ryuki Hyodo, Sébastien Charnoz, Hidenori Genda, Francesco Pignatale, Pascal RosenblattAbstract:Recent works have shown that Martian moons Phobos and Deimos may have accreted within a giant impact-generated disk whose composition is about an equal mixture of Martian material and impactor material. Just after the giant impact, the Martian surface is heated up to $\sim3000-6000$ K and the building blocks of moons, including volatile-rich vapor, are heated up to $\sim2000$ K. In this paper, we investigate the volatile loss from the building blocks of Phobos and Deimos by hydrodynamic escape of vapor and radiation pressure on condensed particles. We show that a non-negligible amount of volatiles ($> 10\%$ of the vapor with temperature $> 1000$ K via hydrodynamic escape, and moderately volatile dusts that condense at $\sim700-2000$ K via radiation pressure) could be removed just after the impact during their first signle orbit from their pericenters to apocenters. Our results indicate that bulk Phobos and Deimos are depleted in volatile elements. Together with future explorations such as JAXA's MMX (Martian Moons eXploration) mission, our results would be used to constrain the origin of Phobos and Deimos.
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On the Impact Origin of Phobos and Deimos. III. Resulting Composition from Different Impactors
The Astrophysical Journal, 2018Co-Authors: Francesco Pignatale, Pascal Rosenblatt, Sébastien Charnoz, Ryuki Hyodo, Tomoki Nakamura, Hidenori GendaAbstract:The origin of Phobos and Deimos in a giant impact-generated disk is gaining larger attention. Although this scenario has been the subject of many studies, an evaluation of the chemical composition of the Mars's moons in this framework is missing. The chemical composition of Phobos and Deimos is unconstrained. The large uncertainties about the origin of the mid-infrared features; the lack of absorption bands in the visible and near-infrared spectra; and the effects of secondary processes on the moons' surfaces make the determination of their composition very difficult using remote sensing data. Simulations suggest a formation of a disk made of gas and melt with their composition linked to the nature of the impactor and Mars. Using thermodynamic equilibrium, we investigate the composition of dust (condensates from gas) and solids (from a cooling melt) that result from different types of Mars impactors (Mars-, CI-, CV-, EH-, and comet-like). Our calculations show a wide range of possible chemical compositions and noticeable differences between dust and solids, depending on the considered impactors. Assuming that Phobos and Deimos resulted from the accretion and mixing of dust and solids, we find that the derived assemblage (dust-rich in metallic iron, sulfides and/or carbon, and quenched solids rich in silicates) can be compatible with the observations. The JAXA's Martian Moons eXploration (MMX) mission will investigate the physical and chemical properties of Phobos and Deimos, especially sampling from Phobos, before returning to Earth. Our results could be then used to disentangle the origin and chemical composition of the pristine body that hit Mars and suggest guidelines for helping in the analysis of the returned samples.
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Accretion of Phobos and Deimos in an extended debris disc stirred by transient moons
Nature Geoscience, 2016Co-Authors: Pascal Rosenblatt, Sébastien Charnoz, Kevin M. Dunseath, Mariko Terao-dunseath, Antony Trinh, Ryuki Hyodo, Hidenori Genda, Stéven ToupinAbstract:Phobos and Deimos, the two small satellites of Mars, are thought either to be asteroids captured by the planet or to have formed in a disc of debris surrounding Mars following a giant impact. Both scenarios, however, have been unable to account for the current Mars system. Here we use numerical simulations to suggest that Phobos and Deimos accreted from the outer portion of a debris disc formed after a giant impact on Mars. Larger moons are formed from the denser inner disc and migrate outwards due to gravitational interactions with it. The resulting orbital resonances spread outwards and gather the dispersed debris, facilitating accretion into two satellites of sizes similar to Phobos and Deimos. The larger inner moons fall back to Mars after about 5 million years due to the tidal pull of the planet, after which the two outer satellites evolve into Phobos- and Deimos-like orbits. Our results clarify why Mars has two small satellites instead of one large moon. Our model predicts that Phobos and Deimos are composed of a mixture of material from Mars and the impactor.
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Accretion of Phobos and Deimos in an extended debris disc stirred by transient moons
Nature Geoscience, 2016Co-Authors: Pascal Rosenblatt, Sébastien Charnoz, Kevin M. Dunseath, Mariko Terao-dunseath, Antony Trinh, Ryuki Hyodo, Hidenori Genda, Stéven ToupinAbstract:Phobos and Deimos, the two small satellites of Mars, are thought either to be asteroids captured by the planet or to have formed in a disc of debris surrounding Mars following a giant impact^ 1 , 2 , 3 , 4 . Both scenarios, however, have been unable to account for the current Mars system^ 1 , 2 , 3 , 5 , 6 , 7 . Here we use numerical simulations to suggest that Phobos and Deimos accreted from the outer portion of a debris disc formed after a giant impact on Mars. In our simulations, larger moons form from material in the denser inner disc and migrate outwards due to gravitational interactions with the disc. The resulting orbital resonances spread outwards and gather dispersed outer disc debris, facilitating accretion into two satellites of sizes similar to Phobos and Deimos. The larger inner moons fall back to Mars after about 5 million years due to the tidal pull of the planet, after which the two outer satellites evolve into Phobos- and Deimos-like orbits. The proposed scenario can explain why Mars has two small satellites instead of one large moon. Our model predicts that Phobos and Deimos are composed of a mixture of material from Mars and the impactor. Mars has two small moons that may have formed in the aftermath of a giant impact. Simulations suggest that Phobos and Deimos accreted from the disperse outer region of the debris disc that was stirred up by short-lived larger moons.
Scott L. Murchie - One of the best experts on this subject based on the ideXlab platform.
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Overview of Phobos/Deimos Regolith Ion Sample Mission (PRISM) concept
CubeSats and NanoSats for Remote Sensing II, 2018Co-Authors: Pamela Clark, Andrew S. Rivkin, Michael R. Collier, M. J. Schaible, William M. Farrell, David Folta, Kyle M. Hughes, John W. Keller, Ben Malphrus, Scott L. MurchieAbstract:Far more definitive information on composition is required to resolve the question of origin for the Martian moons Phobos and Deimos. Current infrared spectra of the objects are inconclusive due to the lack of strong diagnostic features. Definitive compositional measurements of Phobos could be obtained using in-situ X-ray, gamma-ray, or neutron spectroscopy or collecting and returning samples to Earth for analysis. We have proposed, in lieu of those methods, to derive Phobos and Deimos compositional data from secondary ion mass spectrometry (SIMS) measurements by calibrating the instrument to elemental abundance measurements made for known samples in the laboratory. We describe the Phobos/Deimos Regolith Ion Sample Mission (PRISM) concept here. PRISM utilizes a high-resolution TOF plasma composition analyzer to make SIMS measurements by observing the sputtered species from various locations of the moons' surfaces. In general, the SIMS technique and ion mass spectrometers complement and expand quadrupole mass spectrometer measurements by collecting ions that have been energized to higher energies, 50-100 eV, and making measurements at very low densities and pressures. Furthermore, because the TOF technique accepts all masses all the time, it obtains continuous measurements and does not require stepping through masses. The instrument would draw less than 10 W and weigh less than 5 kg. The spacecraft, nominally a radiation-hardened 12U CubeSat, would use a low-thrust Solar Electric Propulsion system to send it on a two-year journey to Mars, where it would co-orbit with Deimos and then Phobos at distances as low as 27 km.
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Phobos and Deimos
Asteroids IV, 2015Co-Authors: Scott L. Murchie, Peter C. Thomas, Andrew S. Rivkin, Nancy L. ChabotAbstract:Once the Galilean satellites of Jupiter were discovered and the Copernican model of the solar system became widely accepted, Mars’ apparent lack of a moon was notable. By the end of the seventeenth century, Saturn was known to have at least five satellites, a number that swelled to seven by the end of the eighteenth century. By 1800 a new planet, Uranus, was discovered and found to have at least two satellites. By 1870, two more uranian satellites and another saturnian satellite were detected, along with another new planet (Neptune) with its own satellite. Yet Mars remained moonless. Based on numerology, Kepler predicted that Mars should have two satellites, as two made the most sense when interpolating between Earth’s single moon and Jupiter’s four. Jonathan Swift and Voltaire both “predicted” that Mars would have two moons, but their predictions were based on satire (Hall, 1878). Both William Herschel and Heinrich Louis d’Arrest performed unsuccessful searches for martian moons before Asaph Hall, using the U.S. Naval Observatory 26-inch (66cm) refractor, found first Deimos then Phobos during the excellent Mars apparition of 1877. Because of the primitive state of astrophotography, only visual observations using eyepieces were possible at the time. The satellites were named for characters in the Iliad, Phobos (Fear) and Deimos (Terror), who are the attendants of the god Ares, the Greek equivalent of the Roman god Mars. Despite searches for additional satellites, using both groundand spacecraft-based observations, no additional satellites of Mars have been found within its Hill sphere to a diameter of 180 m assuming an albedo of 0.07 (Sheppard et al., 2004). Given the close proximity of Phobos and Deimos to Mars, positional measurements were typically the only ones undertaken. Pascu et al. (2013) compiled and reviewed these measurements as well as other early observations. A focus of early observations was the secular acceleration of Phobos in its orbit (e.g., Sharpless, 1945), now known to originate from tidal effects that cause the moon to spiral in toward Mars, which eventually will result in Phobos’ impact (Burns, 1978). The first photometric study to estimate the moons’ diameters from their brightnesses, by Edward Charles Pickering of the Harvard College Observatory and reported by Hall (1878), suggested diameters of 9 km for Deimos and 11 km for Phobos. These assumed a Mars-like albedo and hence resulted in diameters smaller than the actual values. Just prior to the first spacecraft encounters with the moons, a combination of photoelectric photometry (Harris, 1961) and albedo estimates from polarimetry (Zellner, 1972) resulted in diameter estimates within 10% of current values (Zellner and Capen, 1974).
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spectral absorptions on phobos and Deimos in the visible near infrared wavelengths and their compositional constraints
Icarus, 2014Co-Authors: Abigail A. Fraeman, Scott L. Murchie, R. E. Arvidson, R. V. Morris, A S Rivkin, Roger N. Clark, Faith VilasAbstract:Abstract Absorption features on Phobos and Deimos in the visible/near infrared wavelength region (0.4–3.9 μm) are mapped using observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Fe 2+ electronic absorptions diagnostic of olivine and pyroxene are not detected. A broad absorption centered around 0.65 μm within the red spectral units of both moons is detected, and this feature is also evident in telescopic, Pathfinder, and Phobos-2 observations of Phobos. A 2.8 μm metal–OH combination absorption on both moons is also detected in the CRISM data, and this absorption is shallower in the Phobos blue unit than in the Phobos red unit and Deimos. The strength, position, and shape of both of the 0.65 μm and 2.8 μm absorptions are similar to features seen on red-sloped, low-albedo primitive asteroids. Two end-member hypotheses are presented to explain the spectral features on Phobos and Deimos. The first invokes the presence of highly desiccated Fe-phyllosilicate minerals indigenous to the bodies, and the second invokes Rayleigh scattering and absorption of small iron particles formed by exogenic space weathering processing, coupled with implantation of H from solar wind. Both end-member hypotheses may play a role, and in situ exploration will be needed to ultimately determine the underlying causes for the pair of spectral features observed on Phobos and Deimos.
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Spectral absorptions on Phobos and Deimos in the visible/near infrared wavelengths and their compositional constraints
Icarus, 2014Co-Authors: Abigail A. Fraeman, Scott L. Murchie, Andrew S. Rivkin, R. V. Morris, Raymond E. Arvidson, Roger N. Clark, Faith VilasAbstract:Abstract Absorption features on Phobos and Deimos in the visible/near infrared wavelength region (0.4–3.9 μm) are mapped using observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Fe 2+ electronic absorptions diagnostic of olivine and pyroxene are not detected. A broad absorption centered around 0.65 μm within the red spectral units of both moons is detected, and this feature is also evident in telescopic, Pathfinder, and Phobos-2 observations of Phobos. A 2.8 μm metal–OH combination absorption on both moons is also detected in the CRISM data, and this absorption is shallower in the Phobos blue unit than in the Phobos red unit and Deimos. The strength, position, and shape of both of the 0.65 μm and 2.8 μm absorptions are similar to features seen on red-sloped, low-albedo primitive asteroids. Two end-member hypotheses are presented to explain the spectral features on Phobos and Deimos. The first invokes the presence of highly desiccated Fe-phyllosilicate minerals indigenous to the bodies, and the second invokes Rayleigh scattering and absorption of small iron particles formed by exogenic space weathering processing, coupled with implantation of H from solar wind. Both end-member hypotheses may play a role, and in situ exploration will be needed to ultimately determine the underlying causes for the pair of spectral features observed on Phobos and Deimos.
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Constraints on the Compositions of Phobos and Deimos from Mineral Absorptions
2013Co-Authors: Abigail A. Fraeman, Scott L. Murchie, R. E. Arvidson, Andrew S. Rivkin, R. V. MorrisAbstract:The compositions of Phobos and Deimos have remained controversial despite multiple Earth- and space-based observations acquired during the last 40 years. Phobos is composed of at least two spectral units that are both dark yet distinct at visible to near infrared wavelenghts; a spectrally red-sloped "red" unit covers most of the moon and a less red-sloped "blue" unit is present in the ejecta of the approximately 9-km diameter impact crater Stickney [1,2]. Deimos is similar spectrally to Phobos' "red" unit [2]. Here we report results from mapping mineral absorptions on Phobos and Deimos using visible/near infrared observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). We find evidence for an absorption feature at 0.65 m in the Phobos red unit and Deimos that is reproducible in observations from other instruments. The phase responsible is uncertain but may be a Fe-bearing phyllosilicate and/or graphite, consistent with the notion that Phobos and Deimos have compositions similar to CM carbonaceous chondrites [3].