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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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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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Deformation and thermal evolution of the ice shell on Enceladus
Kvorka, Jakub ; Čadek, Ondřej (advisor) ; Souček, Ondřej (referee)
In the last two decades, successful space missions to Jupiter and Saturn provi- ded important data bearing information about topography and internal structure of icy bodies in the outer Solar System. Some of these bodies contain subsurface reservoirs of liquid water in contact with an outer shell made of solid ice. One of the possibilities how to explain the observed topography of a moon is to use its thermal production as the energy source that produces deformation of the ice crust covering the body. In this study, we develop a simplified mathematical mo- del of thermal-mechanical evolution of the ice crust including the effect of phase transition at its bottom boundary. The appropriate system of partial differential equations is coded in Fortran95 and used to study the surface features developed in response to heat flux anomalies imposed on the top of the subsurface ocean. The results obtained for Enceladus, Europa and Titan show that the observed topography of these moons can be explained only for a large grain size and the ice crust behaving elastically near the upper boundary. 1
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