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Re Vision
Švehla, Jakub ; Šrámek, Jan (referee) ; Kögler, Žaneta (advisor)
In form of 3D animation the thesis depicts the steps of mankind towards the expansion of civilization beyond planet Earth. Chronologically it exposes essential moments of technological development (in major) preceding the journey for the distant planets. Images of today's state of civilization are combined with constructions of former theoretical concepts and with fully fictitious elements to form visuals illustrating the roadmap to extraterrestrial expansion.
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Predictive software for Earth collision with Near Eartch Objects
Stopka, Jiří ; Daněk, Vladimír (referee) ; Bartoněk, Jaroslav (advisor)
Aim of this bachelor’s thesis is to research and discuss the basics of orbital mechanics and their application on a real problem. The application of orbital mechanics is made by creating a software for predicting Earth’s collision with Near-Earth Objects in Borland Delphi 7 development enviroment. The created software should be able to predict close approaches of Earth and Near-Earth Objects in a time scale selected by user and issue a warning in case of a dangerous close approach.
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Inner belt asteroids in the spin-orbital resonance
Vraštil, Jan ; Vokrouhlický, David (advisor)
Context: Slivan (2002) determined spin state of ten asteroids in the Koronis family. Surprisingly, all four asteroids with prograde sense of rotation were shown to have spin axes nearly parallel in the inertial space. All asteroids with retrograde sense of rotation had large obliquities and rotation periods either short or long. It was shown that Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect can explain all these peculiar facts. In particular, it drives spin axes of the prograde rotators to be captured in a secular spin-orbital resonance known as Cassini state 2. Vokrouhlický et al. (2002) dubbed these configurations "Slivan states". Aims: A question arises whether Slivan states could exist also in other regions of the main asteroid belt, in particular its inner part, where observations are most easily obtained. Here, however, dynamical difficulties arise due to convergence of the proper frequency s and the planetary frequency s6. We investigate possibilities of a long-term stable capture in the Slivan state in the inner part of the main belt. Method: We used SWIFT integrator to determine orbital evolution of selected asteroids in the inner part of the main belt. In the case of 20 Massalia, we observed the asteroid in 2011, and used these new data to help better solve the rotation state using the...
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Predictive software for Earth collision with Near Eartch Objects
Stopka, Jiří ; Daněk, Vladimír (referee) ; Bartoněk, Jaroslav (advisor)
Aim of this bachelor’s thesis is to research and discuss the basics of orbital mechanics and their application on a real problem. The application of orbital mechanics is made by creating a software for predicting Earth’s collision with Near-Earth Objects in Borland Delphi 7 development enviroment. The created software should be able to predict close approaches of Earth and Near-Earth Objects in a time scale selected by user and issue a warning in case of a dangerous close approach.
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Inner belt asteroids in the spin-orbital resonance
Vraštil, Jan ; Vokrouhlický, David (advisor)
Context: Slivan (2002) determined spin state of ten asteroids in the Koronis family. Surprisingly, all four asteroids with prograde sense of rotation were shown to have spin axes nearly parallel in the inertial space. All asteroids with retrograde sense of rotation had large obliquities and rotation periods either short or long. It was shown that Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect can explain all these peculiar facts. In particular, it drives spin axes of the prograde rotators to be captured in a secular spin-orbital resonance known as Cassini state 2. Vokrouhlický et al. (2002) dubbed these configurations "Slivan states". Aims: A question arises whether Slivan states could exist also in other regions of the main asteroid belt, in particular its inner part, where observations are most easily obtained. Here, however, dynamical difficulties arise due to convergence of the proper frequency s and the planetary frequency s6. We investigate possibilities of a long-term stable capture in the Slivan state in the inner part of the main belt. Method: We used SWIFT integrator to determine orbital evolution of selected asteroids in the inner part of the main belt. In the case of 20 Massalia, we observed the asteroid in 2011, and used these new data to help better solve the rotation state using the...
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Hydrodynamic and N-particle simulations of asteroid collisions
Ševeček, Pavel ; Brož, Miroslav (advisor) ; Wünsch, Richard (referee)
We study asteroidal breakups, i.e. fragmentations of targets, subsequent gravitational reaccumulation and formation of small asteroid families. We fo- cused on parent bodies with diameters Dpb = 10 km. Simulations were per- formed with a smoothed-particle hydrodynamics (SPH) code combined with an efficient N-body integrator. We assumed various projectile sizes, impact veloci- ties and angles (125 runs in total). Resulting size-frequency distributions are sig- nificantly different from results of scaled-down simulations with Dpb = 100 km targets (Durda et al. 2007). We thus derive new parametric relations describing fragment distributions, suitable for Monte-Carlo collisional models. We also characterize velocity fields and angular distributions of fragments, which can be used in N-body simulations of asteroid families. Finally, we discuss several uncertainties related to SPH simulations.
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YORP effect on asteroids with heterogeneous distribution of surface thermophysical properties
Chrbolková, Kateřina ; Čapek, David (advisor) ; Ďurech, Josef (referee)
In this thesis, we study the influence of heterogeneous distribution of optical and thermal properties on asteroid surfaces onto the YORP effect. Modelling of the surface heterogeneities is done in three ways. In the first one, we create an impact crater with higher albedo regolith on a regolith-covered asteroid. In the second way, we suppose presence of higher albedo regolith on steep slopes (slope angle > 35◦ ) and in the third one, we state properties of bare rock (with different thermal parameters) in these areas. Then we evaluate the influence of torques caused by scattered or thermally emitted radiation on 200 asteroids based on different distribution of described parameters by means of statistics. We have found that the presence of heterogeneities caused by landslides on asteroid surfaces does not significantly affect the YORP effect with two exceptions: a slight inclination to decelerate the rotation in the case of landslides uncovering bare rock due to critical rotation and significant preference for deceleration in the configurations with uncovered higher albedo regolith on steep slopes. Our data suggest that the influence of heterogeneous distribution of optical properties caused by landslides on the value of typical acceleration time, so-called doubling time td, is 2 % and it does not exceed 5 % in the case...
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Heat diffusion equation and thermophysical modelling of asteroids
Pohl, Leoš ; Ďurech, Josef (advisor) ; Čapek, David (referee)
Light curve inversion is a standard method to determine shapes, rotation periods and spin axis orientations of asteroids. This method can be extended to determine the size, albedo, thermal inertia and surface roughness parameters of an asteroid by including observations in thermal infrared. A solution of the Heat Conduction Equation (HCE) is necessary to model infrared flux from the asteroid. We analyse the accuracy requirements of the extended method for numerical solution of the HCE. We show that current implementation leads to errors in flux that are substantial. We recommend changes in the current implementation of the HCE solving approach to address the accuracy issues. We discuss uniqueness and stability of the solutions produced by the extended method as well as the accuracy of the determined parameters and their stability. Shapes of asteroids are produced and their physical attributes are determined based on light curve and infrared data.
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Inner belt asteroids in the spin-orbital resonance
Vraštil, Jan ; Vokrouhlický, David (advisor) ; Brož, Miroslav (referee)
Context: Slivan (2002) determined spin state of ten asteroids in the Koronis family. Surprisingly, all four asteroids with prograde sense of rotation were shown to have spin axes nearly parallel in the inertial space. All asteroids with retrograde sense of rotation had large obliquities and rotation periods either short or long. It was shown that Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect can explain all these peculiar facts. In particular, it drives spin axes of the prograde rotators to be captured in a secular spin-orbital resonance known as Cassini state 2. Vokrouhlický et al. (2002) dubbed these configurations "Slivan states". Aims: A question arises whether Slivan states could exist also in other regions of the main asteroid belt, in particular its inner part, where observations are most easily obtained. Here, however, dynamical difficulties arise due to convergence of the proper frequency s and the planetary frequency s6. We investigate possibilities of a long-term stable capture in the Slivan state in the inner part of the main belt. Method: We used SWIFT integrator to determine orbital evolution of selected asteroids in the inner part of the main belt. In the case of 20 Massalia, we observed the asteroid in 2011, and used these new data to help better solve the rotation state using the...
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Re Vision
Švehla, Jakub ; Šrámek, Jan (referee) ; Kögler, Žaneta (advisor)
In form of 3D animation the thesis depicts the steps of mankind towards the expansion of civilization beyond planet Earth. Chronologically it exposes essential moments of technological development (in major) preceding the journey for the distant planets. Images of today's state of civilization are combined with constructions of former theoretical concepts and with fully fictitious elements to form visuals illustrating the roadmap to extraterrestrial expansion.
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