The Experts below are selected from a list of 111 Experts worldwide ranked by ideXlab platform
Anastasiia Bendiukova - One of the best experts on this subject based on the ideXlab platform.
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Melting probes revisited – Ice penetration experiments under Mars surface Pressure conditions
Icarus, 2018Co-Authors: Norbert I Komle, Patrick Tiefenbacher, Peter Weiss, Anastasiia BendiukovaAbstract:Abstract Melting probes as vehicles to explore terrestrial ice sheets have been designed and applied successfully since the early 1960’s. Later on, in the 1990’s, various proposals were made to apply such probes also as a means to explore ice sheets on other bodies of the solar system, e.g. Jupiter’s icy satellite Europa or the ice caps of Mars. For this type of subsurface probes the name cryobot has become common. We review both early developments and more recent efforts to develop probes for application in planetary environments, i.e. under low Pressures and low temperatures. The current state of art as well as the pros and cons of the different concepts hitherto considered are described. While many tests with various probes have been done in terrestrial environments, experiments under low surface Pressure conditions are rare. Therefore, we report here on lab tests with a simple melting probe under the range of Pressure and temperature conditions that would be encountered on the surface of Mars and compare them with corresponding tests under a much lower gas Pressure, possibly representative for icy satellites. The contribution of evaporation during the melting and its variation with surface Pressure is also considered. All surface Pressure measurements that have been performed on Mars up to now indicate a surface Pressure above the water Triple Point Pressure (612 Pa). This means that water ice always transforms into the liquid phase when warmed up to 0°C, before it evaporates into the ambient atmosphere. The temporary existence of the liquid phase around the heated tip of the cryobot allows good thermal conductance between probe and surrounding ice, which is an important pre-requisite for efficient melt penetration. Our experiments indicate that under all possible Mars surface Pressures the liquid phase is present when the probe is heated up. This finding confirms experimentally that a probe as it was proposed by Paige (1992) for in situ exploration of the Mars north polar layers would work in the expected way, although the penetration velocity must be expected be lower than under Earth Pressure conditions. A test with the same probe, but under an almost two orders of magnitude lower gas Pressure than on Mars, still indicates the temporary existence of the liquid phase in the contact region between the probe and the surrounding ice.
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melting probes revisited ice penetration experiments under mars surface Pressure conditions
Icarus, 2017Co-Authors: Norbert I Komle, Patrick Tiefenbacher, Peter Weiss, Anastasiia BendiukovaAbstract:Abstract Melting probes as vehicles to explore terrestrial ice sheets have been designed and applied successfully since the early 1960’s. Later on, in the 1990’s, various proposals were made to apply such probes also as a means to explore ice sheets on other bodies of the solar system, e.g. Jupiter’s icy satellite Europa or the ice caps of Mars. For this type of subsurface probes the name cryobot has become common. We review both early developments and more recent efforts to develop probes for application in planetary environments, i.e. under low Pressures and low temperatures. The current state of art as well as the pros and cons of the different concepts hitherto considered are described. While many tests with various probes have been done in terrestrial environments, experiments under low surface Pressure conditions are rare. Therefore, we report here on lab tests with a simple melting probe under the range of Pressure and temperature conditions that would be encountered on the surface of Mars and compare them with corresponding tests under a much lower gas Pressure, possibly representative for icy satellites. The contribution of evaporation during the melting and its variation with surface Pressure is also considered. All surface Pressure measurements that have been performed on Mars up to now indicate a surface Pressure above the water Triple Point Pressure (612 Pa). This means that water ice always transforms into the liquid phase when warmed up to 0°C, before it evaporates into the ambient atmosphere. The temporary existence of the liquid phase around the heated tip of the cryobot allows good thermal conductance between probe and surrounding ice, which is an important pre-requisite for efficient melt penetration. Our experiments indicate that under all possible Mars surface Pressures the liquid phase is present when the probe is heated up. This finding confirms experimentally that a probe as it was proposed by Paige (1992) for in situ exploration of the Mars north polar layers would work in the expected way, although the penetration velocity must be expected be lower than under Earth Pressure conditions. A test with the same probe, but under an almost two orders of magnitude lower gas Pressure than on Mars, still indicates the temporary existence of the liquid phase in the contact region between the probe and the surrounding ice.
Norbert I Komle - One of the best experts on this subject based on the ideXlab platform.
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Melting probes revisited – Ice penetration experiments under Mars surface Pressure conditions
Icarus, 2018Co-Authors: Norbert I Komle, Patrick Tiefenbacher, Peter Weiss, Anastasiia BendiukovaAbstract:Abstract Melting probes as vehicles to explore terrestrial ice sheets have been designed and applied successfully since the early 1960’s. Later on, in the 1990’s, various proposals were made to apply such probes also as a means to explore ice sheets on other bodies of the solar system, e.g. Jupiter’s icy satellite Europa or the ice caps of Mars. For this type of subsurface probes the name cryobot has become common. We review both early developments and more recent efforts to develop probes for application in planetary environments, i.e. under low Pressures and low temperatures. The current state of art as well as the pros and cons of the different concepts hitherto considered are described. While many tests with various probes have been done in terrestrial environments, experiments under low surface Pressure conditions are rare. Therefore, we report here on lab tests with a simple melting probe under the range of Pressure and temperature conditions that would be encountered on the surface of Mars and compare them with corresponding tests under a much lower gas Pressure, possibly representative for icy satellites. The contribution of evaporation during the melting and its variation with surface Pressure is also considered. All surface Pressure measurements that have been performed on Mars up to now indicate a surface Pressure above the water Triple Point Pressure (612 Pa). This means that water ice always transforms into the liquid phase when warmed up to 0°C, before it evaporates into the ambient atmosphere. The temporary existence of the liquid phase around the heated tip of the cryobot allows good thermal conductance between probe and surrounding ice, which is an important pre-requisite for efficient melt penetration. Our experiments indicate that under all possible Mars surface Pressures the liquid phase is present when the probe is heated up. This finding confirms experimentally that a probe as it was proposed by Paige (1992) for in situ exploration of the Mars north polar layers would work in the expected way, although the penetration velocity must be expected be lower than under Earth Pressure conditions. A test with the same probe, but under an almost two orders of magnitude lower gas Pressure than on Mars, still indicates the temporary existence of the liquid phase in the contact region between the probe and the surrounding ice.
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Melting probe experiments under Mars surface conditions – the influence of dust layers, CO2-ice and porosity
Icarus, 2018Co-Authors: Norbert I Komle, Patrick Tiefenbacher, Alexandra KahrAbstract:Abstract This paper reports about recent melting probe experiments under a Pressure that is within the Pressure regime at the surface of Mars. As compared to the results given in Komle et al. (2018), the experiments were extended in several aspects: (i) A deeper ice sample was used in order to study the performance of the probe in the subsurface, (ii) dust layers were embedded inside the samples in order to study their influence on probe penetration, (iii) a surface cover of granular CO2-ice was added, in order to study the performance of the probe in the presence of dry ice, and (iv) the performance of the melting probe in a highly porous ice layer (fresh bonded snow) was studied. In addition, the case of several heating cycles, interrupted by cooling periods, was considered. The experiments demonstrated that the melting probe concept remains successful also in the presence of embedded sand and dust layers, as long as such non-volatile layers are thin, say in the order of centimetres. Under Mars Pressure there is always liquid water present in the melt hole, except for the fresh bonded snow case, where the melt water is absorbed by the surrounding snow. However, because the Mars surface Pressure is typically just slightly above the water Triple Point Pressure, this water is permanently boiling and there are strong convective motions which whirl up dust particles and remove them at least partially from the hot nose region. The presence of a porous CO2-ice cover on the surface does not seriously hamper melting probe penetration, because CO2-ice is much more volatile than water ice and the probe passes such a layer very fast when heated with the same power. In fresh bonded snow, which has very high porosity, the probe penetrates correspondingly faster than in compact ice. Finally, in the last experiment, it was demonstrated explicitly that the melting probe concept works also, when heating is applied in several cycles, interrupted by periods of no active heating.
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melting probes revisited ice penetration experiments under mars surface Pressure conditions
Icarus, 2017Co-Authors: Norbert I Komle, Patrick Tiefenbacher, Peter Weiss, Anastasiia BendiukovaAbstract:Abstract Melting probes as vehicles to explore terrestrial ice sheets have been designed and applied successfully since the early 1960’s. Later on, in the 1990’s, various proposals were made to apply such probes also as a means to explore ice sheets on other bodies of the solar system, e.g. Jupiter’s icy satellite Europa or the ice caps of Mars. For this type of subsurface probes the name cryobot has become common. We review both early developments and more recent efforts to develop probes for application in planetary environments, i.e. under low Pressures and low temperatures. The current state of art as well as the pros and cons of the different concepts hitherto considered are described. While many tests with various probes have been done in terrestrial environments, experiments under low surface Pressure conditions are rare. Therefore, we report here on lab tests with a simple melting probe under the range of Pressure and temperature conditions that would be encountered on the surface of Mars and compare them with corresponding tests under a much lower gas Pressure, possibly representative for icy satellites. The contribution of evaporation during the melting and its variation with surface Pressure is also considered. All surface Pressure measurements that have been performed on Mars up to now indicate a surface Pressure above the water Triple Point Pressure (612 Pa). This means that water ice always transforms into the liquid phase when warmed up to 0°C, before it evaporates into the ambient atmosphere. The temporary existence of the liquid phase around the heated tip of the cryobot allows good thermal conductance between probe and surrounding ice, which is an important pre-requisite for efficient melt penetration. Our experiments indicate that under all possible Mars surface Pressures the liquid phase is present when the probe is heated up. This finding confirms experimentally that a probe as it was proposed by Paige (1992) for in situ exploration of the Mars north polar layers would work in the expected way, although the penetration velocity must be expected be lower than under Earth Pressure conditions. A test with the same probe, but under an almost two orders of magnitude lower gas Pressure than on Mars, still indicates the temporary existence of the liquid phase in the contact region between the probe and the surrounding ice.
Patrick Tiefenbacher - One of the best experts on this subject based on the ideXlab platform.
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Melting probes revisited – Ice penetration experiments under Mars surface Pressure conditions
Icarus, 2018Co-Authors: Norbert I Komle, Patrick Tiefenbacher, Peter Weiss, Anastasiia BendiukovaAbstract:Abstract Melting probes as vehicles to explore terrestrial ice sheets have been designed and applied successfully since the early 1960’s. Later on, in the 1990’s, various proposals were made to apply such probes also as a means to explore ice sheets on other bodies of the solar system, e.g. Jupiter’s icy satellite Europa or the ice caps of Mars. For this type of subsurface probes the name cryobot has become common. We review both early developments and more recent efforts to develop probes for application in planetary environments, i.e. under low Pressures and low temperatures. The current state of art as well as the pros and cons of the different concepts hitherto considered are described. While many tests with various probes have been done in terrestrial environments, experiments under low surface Pressure conditions are rare. Therefore, we report here on lab tests with a simple melting probe under the range of Pressure and temperature conditions that would be encountered on the surface of Mars and compare them with corresponding tests under a much lower gas Pressure, possibly representative for icy satellites. The contribution of evaporation during the melting and its variation with surface Pressure is also considered. All surface Pressure measurements that have been performed on Mars up to now indicate a surface Pressure above the water Triple Point Pressure (612 Pa). This means that water ice always transforms into the liquid phase when warmed up to 0°C, before it evaporates into the ambient atmosphere. The temporary existence of the liquid phase around the heated tip of the cryobot allows good thermal conductance between probe and surrounding ice, which is an important pre-requisite for efficient melt penetration. Our experiments indicate that under all possible Mars surface Pressures the liquid phase is present when the probe is heated up. This finding confirms experimentally that a probe as it was proposed by Paige (1992) for in situ exploration of the Mars north polar layers would work in the expected way, although the penetration velocity must be expected be lower than under Earth Pressure conditions. A test with the same probe, but under an almost two orders of magnitude lower gas Pressure than on Mars, still indicates the temporary existence of the liquid phase in the contact region between the probe and the surrounding ice.
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Melting probe experiments under Mars surface conditions – the influence of dust layers, CO2-ice and porosity
Icarus, 2018Co-Authors: Norbert I Komle, Patrick Tiefenbacher, Alexandra KahrAbstract:Abstract This paper reports about recent melting probe experiments under a Pressure that is within the Pressure regime at the surface of Mars. As compared to the results given in Komle et al. (2018), the experiments were extended in several aspects: (i) A deeper ice sample was used in order to study the performance of the probe in the subsurface, (ii) dust layers were embedded inside the samples in order to study their influence on probe penetration, (iii) a surface cover of granular CO2-ice was added, in order to study the performance of the probe in the presence of dry ice, and (iv) the performance of the melting probe in a highly porous ice layer (fresh bonded snow) was studied. In addition, the case of several heating cycles, interrupted by cooling periods, was considered. The experiments demonstrated that the melting probe concept remains successful also in the presence of embedded sand and dust layers, as long as such non-volatile layers are thin, say in the order of centimetres. Under Mars Pressure there is always liquid water present in the melt hole, except for the fresh bonded snow case, where the melt water is absorbed by the surrounding snow. However, because the Mars surface Pressure is typically just slightly above the water Triple Point Pressure, this water is permanently boiling and there are strong convective motions which whirl up dust particles and remove them at least partially from the hot nose region. The presence of a porous CO2-ice cover on the surface does not seriously hamper melting probe penetration, because CO2-ice is much more volatile than water ice and the probe passes such a layer very fast when heated with the same power. In fresh bonded snow, which has very high porosity, the probe penetrates correspondingly faster than in compact ice. Finally, in the last experiment, it was demonstrated explicitly that the melting probe concept works also, when heating is applied in several cycles, interrupted by periods of no active heating.
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melting probes revisited ice penetration experiments under mars surface Pressure conditions
Icarus, 2017Co-Authors: Norbert I Komle, Patrick Tiefenbacher, Peter Weiss, Anastasiia BendiukovaAbstract:Abstract Melting probes as vehicles to explore terrestrial ice sheets have been designed and applied successfully since the early 1960’s. Later on, in the 1990’s, various proposals were made to apply such probes also as a means to explore ice sheets on other bodies of the solar system, e.g. Jupiter’s icy satellite Europa or the ice caps of Mars. For this type of subsurface probes the name cryobot has become common. We review both early developments and more recent efforts to develop probes for application in planetary environments, i.e. under low Pressures and low temperatures. The current state of art as well as the pros and cons of the different concepts hitherto considered are described. While many tests with various probes have been done in terrestrial environments, experiments under low surface Pressure conditions are rare. Therefore, we report here on lab tests with a simple melting probe under the range of Pressure and temperature conditions that would be encountered on the surface of Mars and compare them with corresponding tests under a much lower gas Pressure, possibly representative for icy satellites. The contribution of evaporation during the melting and its variation with surface Pressure is also considered. All surface Pressure measurements that have been performed on Mars up to now indicate a surface Pressure above the water Triple Point Pressure (612 Pa). This means that water ice always transforms into the liquid phase when warmed up to 0°C, before it evaporates into the ambient atmosphere. The temporary existence of the liquid phase around the heated tip of the cryobot allows good thermal conductance between probe and surrounding ice, which is an important pre-requisite for efficient melt penetration. Our experiments indicate that under all possible Mars surface Pressures the liquid phase is present when the probe is heated up. This finding confirms experimentally that a probe as it was proposed by Paige (1992) for in situ exploration of the Mars north polar layers would work in the expected way, although the penetration velocity must be expected be lower than under Earth Pressure conditions. A test with the same probe, but under an almost two orders of magnitude lower gas Pressure than on Mars, still indicates the temporary existence of the liquid phase in the contact region between the probe and the surrounding ice.
Peter Weiss - One of the best experts on this subject based on the ideXlab platform.
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Melting probes revisited – Ice penetration experiments under Mars surface Pressure conditions
Icarus, 2018Co-Authors: Norbert I Komle, Patrick Tiefenbacher, Peter Weiss, Anastasiia BendiukovaAbstract:Abstract Melting probes as vehicles to explore terrestrial ice sheets have been designed and applied successfully since the early 1960’s. Later on, in the 1990’s, various proposals were made to apply such probes also as a means to explore ice sheets on other bodies of the solar system, e.g. Jupiter’s icy satellite Europa or the ice caps of Mars. For this type of subsurface probes the name cryobot has become common. We review both early developments and more recent efforts to develop probes for application in planetary environments, i.e. under low Pressures and low temperatures. The current state of art as well as the pros and cons of the different concepts hitherto considered are described. While many tests with various probes have been done in terrestrial environments, experiments under low surface Pressure conditions are rare. Therefore, we report here on lab tests with a simple melting probe under the range of Pressure and temperature conditions that would be encountered on the surface of Mars and compare them with corresponding tests under a much lower gas Pressure, possibly representative for icy satellites. The contribution of evaporation during the melting and its variation with surface Pressure is also considered. All surface Pressure measurements that have been performed on Mars up to now indicate a surface Pressure above the water Triple Point Pressure (612 Pa). This means that water ice always transforms into the liquid phase when warmed up to 0°C, before it evaporates into the ambient atmosphere. The temporary existence of the liquid phase around the heated tip of the cryobot allows good thermal conductance between probe and surrounding ice, which is an important pre-requisite for efficient melt penetration. Our experiments indicate that under all possible Mars surface Pressures the liquid phase is present when the probe is heated up. This finding confirms experimentally that a probe as it was proposed by Paige (1992) for in situ exploration of the Mars north polar layers would work in the expected way, although the penetration velocity must be expected be lower than under Earth Pressure conditions. A test with the same probe, but under an almost two orders of magnitude lower gas Pressure than on Mars, still indicates the temporary existence of the liquid phase in the contact region between the probe and the surrounding ice.
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melting probes revisited ice penetration experiments under mars surface Pressure conditions
Icarus, 2017Co-Authors: Norbert I Komle, Patrick Tiefenbacher, Peter Weiss, Anastasiia BendiukovaAbstract:Abstract Melting probes as vehicles to explore terrestrial ice sheets have been designed and applied successfully since the early 1960’s. Later on, in the 1990’s, various proposals were made to apply such probes also as a means to explore ice sheets on other bodies of the solar system, e.g. Jupiter’s icy satellite Europa or the ice caps of Mars. For this type of subsurface probes the name cryobot has become common. We review both early developments and more recent efforts to develop probes for application in planetary environments, i.e. under low Pressures and low temperatures. The current state of art as well as the pros and cons of the different concepts hitherto considered are described. While many tests with various probes have been done in terrestrial environments, experiments under low surface Pressure conditions are rare. Therefore, we report here on lab tests with a simple melting probe under the range of Pressure and temperature conditions that would be encountered on the surface of Mars and compare them with corresponding tests under a much lower gas Pressure, possibly representative for icy satellites. The contribution of evaporation during the melting and its variation with surface Pressure is also considered. All surface Pressure measurements that have been performed on Mars up to now indicate a surface Pressure above the water Triple Point Pressure (612 Pa). This means that water ice always transforms into the liquid phase when warmed up to 0°C, before it evaporates into the ambient atmosphere. The temporary existence of the liquid phase around the heated tip of the cryobot allows good thermal conductance between probe and surrounding ice, which is an important pre-requisite for efficient melt penetration. Our experiments indicate that under all possible Mars surface Pressures the liquid phase is present when the probe is heated up. This finding confirms experimentally that a probe as it was proposed by Paige (1992) for in situ exploration of the Mars north polar layers would work in the expected way, although the penetration velocity must be expected be lower than under Earth Pressure conditions. A test with the same probe, but under an almost two orders of magnitude lower gas Pressure than on Mars, still indicates the temporary existence of the liquid phase in the contact region between the probe and the surrounding ice.
A. Keller - One of the best experts on this subject based on the ideXlab platform.
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Dependence of the lamellar thickness of an extended-chain single crystal of polyethylene on the degree of supercooling and the Pressure
Journal of the Chemical Society Faraday Transactions, 1995Co-Authors: Masamichi Hikosaka, Sanjay Rastogi, H. Okada, Akihiko Toda, A. KellerAbstract:The dependence of the lamellar thickness (I) of an extended-chain single crystal (ECSC) of polyethylene (PE) crystallized at various Pressures below or at the Triple-Point Pressure (Ptri= 0.5 GPa) on the degree of super-cooling (ΔT) and the Pressure have been studied. The value of I increased with the decrease in ΔT[i.e. increase in the crystallization temperature (Tc)] at a fixed Pressure, similar to the well known ΔT dependence of I for a folded-chain single crystal (FCC). The observed maximum value of I, obtained at the lowest ΔT(Imax) increased with increasing Pressure and the crystal changed from FCC to an extended-chain crystal (ECC) at ca. 0.25 GPa. Application of the chain-sliding diffusion theory, previously proposed by one of the authors (M.H.) was found to explain well observed significant ΔT dependence of I and the Pressure dependence of Imax. It was proposed that the value of I is determined by the cessation of lamellar thickening growth at the phase transition from metastable hexagonal to stable orthorhombic. The phase transition was also studied and it is suggested to be a nucleation-controlled process of the primary nucleus.
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Equilibrium Triple Point Pressure and Pressure-temperature phase diagram of polyethylene
Polymer, 1992Co-Authors: M. Hikosaka, K Tsukijima, Sanjay Rastogi, A. KellerAbstract:Abstract The equilibrium Triple Point and Pressure and temperature phase diagram of polyethylene were obtained by in situ optical microscopic and X-ray observations of the melting temperature of hexagonal and orthorhombic isolated extended chain single crystals at high Pressure. The melting temperatures of extended chain crystals still showed a ΔT dependence at high Pressure, which has been neglected in previous studies. The Triple Point Pressure and temperature were 0.5 × 108 − 1.5 × 108 Pa and 20–30°C higher than those previously obtained by the d.t.a. method. These results suggest that lamellar thickness dependence is important even in extended chain crystals to obtain equilibrium thermodynamic physical quantities of polymers.
