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Hydrosphere structure of icy satellites
Košíková, Terézia ; Běhounková, Marie (advisor) ; Kalousová, Klára (referee)
The exploration of potential life on other celestial bodies within the Solar System is one of the key questions in planetary science. In this work, we focused on determining the hydrosphere of the icy moons Ganymede and Europa in order to determine possible obstacles in habitability due to the presence of the high-pressure ices. We used known thermodynamic properties and satellite parameters to create an algorithm that deter- mined their structures. We found that on Ganymede high-pressure ices are present in a wide range of pressure and temperature conditions, which may prevent the transfer of minerals between the silicates and the subsurface ocean. For Europa, we found that the occurrence of high-pressure ice phases is very unlikely in its hydrosphere. However, the latest data for Europa complicates the exact determination of its structure and Europa may contain thinner hydrosphere and ocean than originally thought. 1
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Viscoelastic deformation of ice bodies in the Solar System
Kihoulou, Martin ; Kalousová, Klára (advisor) ; Běhounková, Marie (referee)
Two icy bodies of the Solar System, a moon of Saturn Titan and a dwarf planet Pluto, are studied in this thesis. Titan's polar radius is smaller than expected, which can be explained by soaking of the ethane rain followed by methane- ethane substitution in the crust. We treat the crust as continuum with viscoelastic (Maxwell) rheology and solve its loading by spectral method. We obtain results in agreement with those published. On Pluto, the position of Sputnik Planitia crater close to the tidal axis might be a sign of subsurface ocean. This unlikely location can be explained by reorientation of the body, if the gravity anomaly of the crater is positive. This requires isostatic compensation, which would mean a material denser than ice, e.g. water, filling the lower crater. Solving by spectral method we obtain results consistent with the hypothesis. However, solving viscous deformation in domain with free surface by finite element method indicates that the lower crater relaxes too fast to explain reorientation. 1
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Impact crater relaxation throughout the Solar System
Kihoulou, Martin ; Kalousová, Klára (advisor) ; Velímský, Jakub (referee)
Title: Impact crater relaxation throughout the Solar System Author: Martin Kihoulou Department: Department of Geophysics Supervisor: RNDr. Klára Kalousová, Ph.D., Department of Geophysics Abstract: In this thesis, we study the viscous relaxation of an impact-deformed icy shell of a dwarf planet Pluto. Motivation for this work is the position of Sputnik Planitia, a 1000 km wide, nitrogen-filled elliptic basin, which is located very close to Pluto-Charon tidal axis. Given this unlikely position on Pluto's sur- face, it was suggested that the basin was formed elsewhere and the whole body reoriented afterwards. For the reorientation to occur, the basin has to generate a positive gravity anomaly for which a combination of impact-related subsurface ocean uplift, ejecta blanket and accumulation of nitrogen ice was suggested. How- ever, to maintain the orientation towards the minimum principal axis of inertia until today, the ocean uplift must be present on timescales of billions of years, which may be achieved due to an insulating layer of high viscosity clathrates at the ice/ocean interface. We solve Pluto's ice shell evolution by the finite element method in 2D spherical axisymmetric geometry with an evolving free surface and assuming a viscous rheology. Our results show that the thermal effect of the im- pact...
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Internal dynamics of Mars: a study based on gravitational and topographic data
Kalousová, Klára
In the present work we deal with the model of elastic lithosphere thickness on Mars. We assume that the surface load of the planet is compensated only by elastic lithosphere deflection and formulate the spatial inversion based on the comparison between predicted and observed geoid. Performing very extensive tests on this inversion in the two dimensional axisymmetric geometry we gain its best parameters. Then we invert the real data and construct the models of Martian elastic lithosphere thickness for filters of variable width. We focus on some topographically significant areas, establish the elastic lithosphere thickness below them and compare the obtained values with published results. For some areas we get agreement. Assigning the age to particular areas we find the growth of elastic lithosphere thickness during time, which is in agreement with the so-called principle of frozen lithosphere.
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Exotic heat sources in exoEarths
Verkinová, Natália ; Běhounková, Marie (advisor) ; Kalousová, Klára (referee)
This thesis focuses on the comparison between the tidal heating and Joule hea- ting representing an unusual heat source. First, a parametric study was performed on a model planet orbiting a low-mass star where the effects of the most impor- tant physical parameters were studied. Then, the possible planetary structure with known radius and total mass was determined for the assumed composition. Application to the TRAPPIST-1b and c planets shows that they undergo intense tidal deformation. If the stellar rotation and magnetic dipole axes are inclined with respect to each other, then Joule heating also applies to them. For a simple structure of planets composed of the mantle and the core, the study shows that energy dissipation from stellar tides dominates in both planets. The extreme he- ating that we observe could lead to rapid overheating of the planet or large-scale melting within the planet. 1
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Subsolidus thermal convection as a key to understanding volatile evolution and internal dynamics of large icy bodies
Ninneman, Brendan ; Kalousová, Klára (advisor) ; Šrámek, Ondřej (referee)
Titan is a unique moon in the solar system as it is the only one with a thick atmo- sphere, and surface lakes and seas. Observations made by the Cassini/Huygens probe showed the potential of a subsurface ocean hidden below the outer crust made of ice. This thesis analyzes the heat transfer through the crust of Titan to understand the long term evolution of the ocean. We developed a finite element model of the heat transfer through a thickening ice crust and investigated the effect of viscosity, internal heat flux, and ammonia concentration in the ocean. While other explanations cannot be ruled out, it was found high values of viscosity and possible ammonia presence could keep the ocean liquid for long periods. 1
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Viscoelastic deformation of ice bodies in the Solar System
Kihoulou, Martin ; Kalousová, Klára (advisor) ; Běhounková, Marie (referee)
Two icy bodies of the Solar System, a moon of Saturn Titan and a dwarf planet Pluto, are studied in this thesis. Titan's polar radius is smaller than expected, which can be explained by soaking of the ethane rain followed by methane- ethane substitution in the crust. We treat the crust as continuum with viscoelastic (Maxwell) rheology and solve its loading by spectral method. We obtain results in agreement with those published. On Pluto, the position of Sputnik Planitia crater close to the tidal axis might be a sign of subsurface ocean. This unlikely location can be explained by reorientation of the body, if the gravity anomaly of the crater is positive. This requires isostatic compensation, which would mean a material denser than ice, e.g. water, filling the lower crater. Solving by spectral method we obtain results consistent with the hypothesis. However, solving viscous deformation in domain with free surface by finite element method indicates that the lower crater relaxes too fast to explain reorientation. 1
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Surface manifestation of melting within the ice shell of Europa
Vach, Dominik ; Kalousová, Klára (advisor) ; Velímský, Jakub (referee)
One of the most interesting extraterrestrial bodies in the Solar System is Europa, the icy satellite of Jupiter. This icy moon might have a sufficiently hospitable environment which could be harbouring life in the subsurface ocean deep under its icy crust. The thesis thoroughly examines the generation process of one of the surface formations called chaotic terrains. These huge areas of ice disruptions which uniquely characterize Europa's surface might play a significant role in the understanding of the inner structure of the moon. The latest research assumes the chaotic terrains form above liquid water lenses perched relatively shallow in the ice shell, however, no numerical simulations have been performed to confirm this theory. The goal of the thesis is to create a model which would validate the theory and explain the formation process of the chaotic terrains. The thesis runs several simulations, and our results suggest these water lenses and the process in the mantle might play a key role in the chaotic terrains formation.
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Internal dynamics of Mars: a study based on gravitational and topographic data
Kalousová, Klára
In the present work we deal with the model of elastic lithosphere thickness on Mars. We assume that the surface load of the planet is compensated only by elastic lithosphere deflection and formulate the spatial inversion based on the comparison between predicted and observed geoid. Performing very extensive tests on this inversion in the two dimensional axisymmetric geometry we gain its best parameters. Then we invert the real data and construct the models of Martian elastic lithosphere thickness for filters of variable width. We focus on some topographically significant areas, establish the elastic lithosphere thickness below them and compare the obtained values with published results. For some areas we get agreement. Assigning the age to particular areas we find the growth of elastic lithosphere thickness during time, which is in agreement with the so-called principle of frozen lithosphere.
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