|
|
The future of human exoplanet settlement
Slezák, Jan ; Dušek,, Jiří (referee) ; Pavlovský, Tomáš (advisor)
The diploma thesis "The future of human exoplanet settlement from the present point of view" is focused on the analysis of the development of the urban compo-sition of the city for the purpose of finding the most suitable concept of the set-tlement. Its foundation is hypothetically put on some of the planets outside the solar system, where could be comparable conditions as on Earth. Installation in these extreme conditions is chosen deliberately so that the essential aspects of the urban layout come to the fore. In this way it is possible at the same time to verify the presumption of stability of the basic assumptions of a functional city and ap-ply the final conclusions in the current conditions as well.
|
|
|
Orbital and internal dynamics of terrestrial planets
Walterová, Michaela ; Běhounková, Marie (advisor) ; Efroimsky, Michael (referee) ; Brož, Miroslav (referee)
Title: Orbital and internal dynamics of terrestrial planets Author: Michaela Walterová Department: Department of Geophysics Supervisor: RNDr. Marie Běhounková, Ph.D., Department of Geophysics Abstract: Close-in exoplanets are subjected to intense tidal interaction with the host star and their secular evolution is strongly affected by the resulting tidal dissipation. The tidal dissipation not only provides an additional heat source for the planet's internal dynamics but it also contributes to the evolution of the planet's spin rate and orbital elements. At the same time, the tidal dissipation itself is also determined by the planet's thermal state and by the spin-orbital parameters. The evolutions of the orbit and of the interior are, therefore, intrinsically linked. In this work, we combine analytical and numerical techniques to gain insight into the interconnection between the internal properties and the orbital evolution, with special focus on the role of tides. After a general study of parametric dependencies of the tidal heating and tidal locking, we present a semi-analytical model assessing the coupled tidally-induced thermal-orbital evolution in systems consisting of a host star and one or two planets. Specifically, we study the thermal-orbital evolution in three systems inspired by existing low-mass...
|
|
|
Exploration of extraterrestrial body impact and UV-driven transformation of atmospheres of terrestrial planets
Knížek, Antonín ; Ferus, Martin (advisor) ; Kabáth, Petr (referee) ; Kopecký, Vladimír (referee)
Keywords: Exoplanets, Earth, Impact, Photochemistry, Infrared Spectroscopy, Atmospheric chemistry Impacts and photochemistry are two very important driving forces for chemical transformation of planetary atmospheres. While strong UV radiation produced by young stars continuously provides a significant amount of energy, impacts are one-time events with far-reaching consequences. Especially important are then impacts on young rocky planets, including the early Earth, because these planets are likely exposed to much higher impact fluxes, commonly called 'heavy bombardment'. This bombardment is the final echo of the turbulent planetary accretion and has prominent significance for planetary environments, e.g., the chemical composition and shape of the planetary surface, the chemistry of atmospheres, aerosol production, and likely the origin of life. Future observations of exoplanets by space telescopes, such as the James Webb Space Telescope or Ariel, as well as ground-based telescopes, such as the Extremely Large Telescope currently under construction in Chile, could determine whether this heavy bombardment represents a common scenario for the evolution of terrestrial planets. Both impacts and photochemistry can be efficiently simulated and studied in laboratory conditions by state-of-the-art methods....
|
|
|
Insolation pattern and surface temperature on extrasolar planets
Káňová, Michaela ; Běhounková, Marie (advisor) ; Čadek, Ondřej (referee)
We study evolution and distribution of surface and near-surface temperature on tidally locked extrasolar terrestrial planets without atmosphere. In order to determine the temperature, insolation patterns depending on eccentricity, obliquity and spin-orbit resonance are computed and thermal diffusion equation is solved in a spherical shell. We discuss the dependence of temperature distribution on physical and geometrical parameters including orbit eccentricity, obliquity of rotational axis, type of spin-orbital resonance, thermal inertia and irradiance incident on the planetary surface (the extra- solar constant). The mean annual temperature is driven especially by the extrasolar constant and may rise up to thousand of kelvins in the most irradiated regions. Effect of eccentricity, obliquity and thermal inertia, in some cases, is on the scale of hundreds of kelvins.
|
|
|
Evolution of terrestrial exoplanets
Káňová, Michaela ; Běhounková, Marie (advisor) ; Čadek, Ondřej (referee)
Observations of terrestrial exoplanets provide a unique statistical set that may improve our knowl- edge of their formation, structure as well as internal and orbital evolution. Close-in extrasolar planets are subjected to strong stellar tides, resulting in an extensive dissipation of mechanical energy (tidal heating), long-term orbital evolution and evolution of the rotational frequency. For the exoplanets on eccentric orbits, the traditional tidal theories predict locking into pseudo-synchronous spin states, for which the rotational frequency is slightly higher than the orbital frequency. Such predictions are, how- ever, in contradiction with the observations of moons in the Solar system, and are a consequence of simplified rheological assumptions. Here, we focus on a numerical approach to the tidal evolution of planetary orbit and rotation in a single-planet system, assuming a Maxwell viscoelastic rheology. We find equillibrium spin states, including the spin-orbit resonances, and discuss their connection with the minima of tidal heating. Locking into a spin-orbit resonance results in an irregular insolation pattern and an unequal surface temperature distribution, affecting the internal dynamics of the planet. The second part of the thesis therefore deals with the evaluation of the surface temperature and...
|
|
|
Phosphine and nitrous oxide as false-positive biosignature gases in planetary spectra
Kaiserová, Tereza ; Ferus, Martin (advisor) ; Kopecký, Vladimír (referee)
5 Abstract This study is dedicated to evaluating the potential for a novel pathway of abiotic synthesis of phosphine (PH3) from phosphorus trioxide (P4O6) by a photocatalytic mechanism on aerosols. The mechanism might explain the recent possible detection of phosphine on Venus. This scenario has recently been suggested theoretically by our team based on an analogy with methane production form carbon dioxide on acidic photochemically-active surfaces of materials, which may account for a possible source of methane on Mars. Methane, just like phosphine, was suggested as an indicator of life on terrestrial planets, including Mars. The theoretical testing of photochemical phosphine generation suggests that even if this gas is present in the atmosphere of Venus it cannot be considered as an indicator of life until the suggested mechanism is excluded theoretically, or by experimental results, or direct evidence of life on Venus. This thesis will be followed by preparation of sophisticated experiments and intensive laboratory research addressing this. Furthermore, the role of nitrous oxide as another false positive biosignature was evaluated in this study. The presence of nitrous oxide can also be explained by processes other than biological, particularly on early planets. This study specifically demonstrates the...
|
|
|
Orbital and internal dynamics of terrestrial planets
Walterová, Michaela ; Běhounková, Marie (advisor) ; Efroimsky, Michael (referee) ; Brož, Miroslav (referee)
Title: Orbital and internal dynamics of terrestrial planets Author: Michaela Walterová Department: Department of Geophysics Supervisor: RNDr. Marie Běhounková, Ph.D., Department of Geophysics Abstract: Close-in exoplanets are subjected to intense tidal interaction with the host star and their secular evolution is strongly affected by the resulting tidal dissipation. The tidal dissipation not only provides an additional heat source for the planet's internal dynamics but it also contributes to the evolution of the planet's spin rate and orbital elements. At the same time, the tidal dissipation itself is also determined by the planet's thermal state and by the spin-orbital parameters. The evolutions of the orbit and of the interior are, therefore, intrinsically linked. In this work, we combine analytical and numerical techniques to gain insight into the interconnection between the internal properties and the orbital evolution, with special focus on the role of tides. After a general study of parametric dependencies of the tidal heating and tidal locking, we present a semi-analytical model assessing the coupled tidally-induced thermal-orbital evolution in systems consisting of a host star and one or two planets. Specifically, we study the thermal-orbital evolution in three systems inspired by existing low-mass...
|
|
|
Consequences of heavy bombardment for chemical and prebiotic evolution on early Mars and Earth
Petera, Lukáš ; Ferus, Martin (advisor) ; Kopecký, Vladimír (referee)
The diploma thesis refers to the results of laboratory research dedicated to the influence of extraterestrial matter impacts onto a possible prebiotic synthesis on early Mars. The influence of understanding of early Mars chemistry for proceeding studies of terrestrian chemical habitus evolution and origin of life is discussed, as well as certain advantages to be made of this research within exoplanetary science. The prebiotic synthesis scenario purposed connects the hypothesis comprising a key role of extraplanetary bodies impacts played in the chemical evolution of an early Earth-like planet to the important processes studied within chemical evolution of life. Asteroid impacts are simulated by laser sparks, while post-impact thermochemical processes are mimetized in the laboratory by a controlled termolysis of certain key species in presence of meteorites, iron-rich clays and several other minerals and rocks presumably present in real impact craters. This particular field of research carried is likely to have an interesting application within current and future investigations of the Gale crater. Impactor mineraly is described on a particular example of a rare Porangaba meteorite, which, thanks to this research, has recently been addressed as a member of unique (comprising 32 bodies) family tree...
|
|
|
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
|
|
|
The future of human exoplanet settlement
Slezák, Jan ; Dušek,, Jiří (referee) ; Pavlovský, Tomáš (advisor)
The diploma thesis "The future of human exoplanet settlement from the present point of view" is focused on the analysis of the development of the urban compo-sition of the city for the purpose of finding the most suitable concept of the set-tlement. Its foundation is hypothetically put on some of the planets outside the solar system, where could be comparable conditions as on Earth. Installation in these extreme conditions is chosen deliberately so that the essential aspects of the urban layout come to the fore. In this way it is possible at the same time to verify the presumption of stability of the basic assumptions of a functional city and ap-ply the final conclusions in the current conditions as well.
|
guest ::
