abstract: Many acidic hot springs in Yellowstone National Park support microbial iron oxidation, reduction, or microbial iron redox cycling (MIRC), as determined by microcosm rate experiments. Microbial dissimilatory iron reduction (DIR) was detected in numerous systems with a pH < 4. Rates of DIR are influenced by the availability of ferric minerals and organic carbon. Microbial iron oxidation (MIO) was detected from pH 2 – 5.5. In systems with abundant Fe (II), dissolved oxygen controls the presence of MIO. Rates generally increase with increased Fe(II) concentrations, but rate constants are not significantly altered by additions of Fe(II). MIRC was detected in systems with abundant ferric mineral deposition. The rates of microbial and abiological iron oxidation were determined in a variety of cold (T= 9-12°C), circumneutral (pH = 5.5-9) environments in the Swiss Alps. Rates of MIO were measured in systems up to a pH of 7.4; only abiotic processes were detected at higher pH values. Iron oxidizing bacteria (FeOB) were responsible for 39-89% of the net oxidation rate at locations where biological iron oxidation was detected. Members of putative iron oxidizing genera, especially Gallionella, are abundant in systems where MIO was measured. Speciation calculations reveal that ferrous iron typically exists as FeCO30, FeHCO3+, FeSO40 or Fe2+ in these systems. The presence of ferrous (bi)carbonate species appear to increase abiotic iron oxidation rates relative to locations without significant concentrations. This approach, integrating geochemistry, rates, and community composition, reveals biogeochemical conditions that permit MIO, and locations where the abiotic rate is too fast for the biotic process to compete. For a reaction to provide habitability for microbes in a given environment, it must energy yield and this energy must dissipate slowly enough to remain bioavailable. Thermodynamic boundaries exist at conditions where reactions do not yield energy, and can be quantified by calculations of chemical energy. Likewise, kinetic boundaries exist at conditions where the abiotic reaction rate is so fast that reactants are not bioavailable; this boundary can be quantified by measurements biological and abiological rates. The first habitability maps were drawn, using iron oxidation as an example, by quantifying these boundaries in geochemical space. / Dissertation/Thesis / Doctoral Dissertation Geological Sciences 2017

O principal objetivo do trabalho foi estimar a possibilidade de sobrevivência de micro-organismos extremófilos na superfície de exoplanetas conhecidos, assim como na superfície de seus eventuais satélites naturais. Foi utilizado um modelo que simula a atmosfera terrestre primordial, composta principalmente por nitrogênio, água e dióxido de carbono. E em se tratando de extremófilos, esses cálculos não foram limitados à Zona Habitável dos sistemas planetários, pois esse conceito foi estendido para uma região mais ampla, a Zona Extremófila, onde a vida pode existir. Extremófilos são micro-organismos terrestres que vivem sob condições extremas de temperatura, nível de radiação, umidade, pressão, salinidade, pH, etc. . Eles são candidatos naturais para habitarem meios ditos extraterrestres onde tais condições são eventualmente encontradas. Alguns exemplos desses ambientes em nosso sistema solar são: Marte, Titã (satélite de Saturno) e Europa (satélite de Júpiter). Há algumas centenas de planetas orbitando outras estrelas (exoplanetas) e a maioria deles são gigantes gasosos, em particular Hot Jupiters. A temperatura superficial de um planeta depende fortemente de seu albedo, de sua distância orbital, de condições geodinâmicas intrínsecas, além do tipo espectral de sua estrela hospedeira. A estimativa dessa temperatura foi obtida considerando o ciclo silicato-carbono e um balanço de energia global, que contribuiram para se obter estimativas da pressão parcial atmosférica devido ao dióxido de carbono e da temperatura média, na superfície dos planetas e/ou de seus satélites hipotéticos. Os eventuais satélites naturais de planetas gigantes podem abrigar vida e essa possibilidade foi testada através da análise das condições de estabilidade orbital desses corpos celestes. Os resultados deste trabalho deverão fornecer subsídios para a hipótese da panspermia. / The main objective of this study is to estimate the chance of survival of microorganisms (extremophiles) on the surface of known exoplanets, as well as on the surface of its potential natural satellites. We used a model that simulates the primordial atmosphere composed by, primarily, nitrogen, water and carbon dioxide. And when it comes to extremophiles, these calculations were not limited to the Habitable Zone of planetary systems, since this concept was extended to a wider region, the Extremophile Zone, where life can exist. Extremophiles are terrestrial microorganisms living under extreme conditions of temperature, light level, humidity, pressure, salinity, pH, etc ... They are natural candidates for living in habitats considered extraterrestrials where such conditions are encountered eventually. Examples of such environments in our solar system are: Mars, Titan (moon of Saturn) and Europe (satellite of Jupiter). There are hundreds of planets orbiting other stars (exoplanets) and most of them are gas giants, particularly Hot Jupiters. The surface temperature of a planet/moon depends heavily on its albedo, its orbital distance, of geodynamic conditions intrinsic, in addition to the spectral type of their host star. The estimate of this temperature was obtained considering the carbon-silicate cycle and a global energy balance, which contributed to obtain estimates of the partial pressure due to atmospheric CO2 and the average temperature on the surface of planets and/or their hypothetical satellites. Natural satellites of giant planets may harbor life, and this possibility was tested by analyzing the conditions of orbital stability of these heavenly bodies. The results of this study should provide support for the hypothesis of panspermia.

This thesis investigates how increased global mean temperatures on Earth, induced by the increase in the luminosity of the Sun as it ages, change the types of habitable environments on the planet at local scales over the next 3 Gyr. Rising temperatures enhance silicate weathering rates, reducing atmospheric CO₂ levels to below the threshold for photosynthesis, while simultaneously pushing environments past the temperature tolerances of plant and animal species. This leads to the end of all plant life and animal life (due to reduced food, O₂ and H₂O availability, as well as higher temperatures) within the next 1 Gyr. The reduction in the extent of the remaining microbial biosphere due to increasing temperatures and rapid ocean evaporation is then modelled, incorporating orbital parameter changes until all known types of life become extinct; a maximum of 2.8 Gyr from the present. The biosignatures associated with these changes are determined and the analysis extended to Earth-like extrasolar planets nearing the end of their habitable lifetimes. In particular, the stages in the main sequence evolutions of Sun-like stars within 10 pc are evaluated and used to extrapolate the stage that an Earth-analogue planet would be at in its habitable evolution, to determine the best candidate systems for a far-future Earth-analogue biosphere, highlighting the Beta Canum Venaticorum system as a good target. One of the most promising biosignatures for a microbial biosphere on the far-future Earth (and similar planets) may be CH₄, which could reach levels in the atmosphere that make it more readily detectable than it is for a present-day Earth-like atmosphere. Determining these biosignatures will help expand the search for life to the wider range of environments that will be found as the habitable exoplanet inventory grows and planets are found at different stages in their habitable evolution.

Future human exploration missions beyond Earth vicinity will be demanding, requiring highly efficient, mass-constrained systems to reduce overall mission costs and complexity. Additionally, long duration transits in space and lack of Earth abort opportunities will increase the physiological and psychological needs of the crew, which will require larger, more capable systems to ensure astronaut well-being. As a result, the objective of habitat design for these missions is to minimize mass and vehicle size while providing adequate space for all necessary equipment and a functional layout for crew health and productivity. Unfortunately, a literature review of methods for evaluating the performance of habitat interior layout designs (including human-in-the-loop mockup tests, in-depth computer-aided design evaluations, and subjective design evaluation studies) found that they are not currently compatible with the conceptual phase of design or optimization because of the qualitative nature of the comparisons and the significant time required to generate and evaluate each layout. Failure to consider interior layout design during conceptual design can lead to increased mass, compromised functionality, and increased risk to crew; particularly for the mass, cost, and volume-constrained long duration human missions to cislunar space and Mars currently being planned by NASA. A comprehensive and timely quantitative method to measure the effectiveness of interior layouts and track the complex, conflicting habitat design objectives earlier in the design process is desired. A new, structured method and modeling framework to quickly measure the effectiveness of habitat interior designs is presented. This method allows for comparison of layouts at conceptual design and advances research in the previously unavailable capability to automate the generation of habitat interiors. This evaluation method features the development of a comprehensive list of quantifiable habitat layout evaluation criteria, the development of automatic methods to measure these criteria from a geometry model and designer inputs, and the application of systems engineering tools and numerical methods to construct a multi-objective value function measuring the overall habitat layout performance. In particular, this method featured the separation of subjective designer preferences and quantitative evaluation criteria measurements to speed layout evaluations and enable automation of interior layout design subject to a set of designer preferences. This method was implemented through the construction of a software tool utilizing geometry modeling coupled with collision detection techniques to identify favorable layouts subject to multiple constraints and objectives (e.g., minimize mass, maximize contiguous habitable volume, maximize task performance efficiency). Notional cis-lunar habitat layouts were evaluated to demonstrate the effectiveness of the method. Furthermore, stochastic optimization was applied to understand and address difficulties with automated layout design, particularly constraint implementation and convergence behavior. Findings from these investigations and implications for future research are discussed.

Notre recherche s’inscrit dans le domaine du génie industriel. Elle porte sur l’amélioration de l’habitabilité de l’habitacle de l’automobile de demain. Cette étude met en évidence l’influence de la conception de l’habitat sur la conception de l’habitacle de l’automobile. L’objectif de ce travail est de proposer un outil destiné à aider le concepteur de l’automobile à introduire les principes de la construction architecturale de l’habitat dans la conception de l’habitacle de l’automobile pour améliorer son habitabilité. Dans notre démarche expérimentale nous avons adopté des principes de la méthode d’analyse des tendances conjointe comme les mappings et les planches de catégorisation. Cette démarche montre que les concepteurs de l’automobile ont orienté leur démarche vers l’intégration de plus en plus de principes de la construction architecturale de l’habitat dans la conception de l’habitacle des concept-cars. L’enquête que nous avons effectuée auprès des architectes et des designers nous a confirmé que l’habitat et l’automobile partagent les mêmes critères de l’habitabilité. Aussi, elle nous a affirmé l’impact positif des principes de la construction architecturale de l’habitat sur l’amélioration des critères de l’habitabilité dans l’espace de l’habitacle automobile. Notre recherche ouvre des perspectives pour analyser l’impact des autres secteurs d’influence comme l’aéronautique et l’électronique sur la conception de l’automobile. Aussi, elle montre l’importance de l’analyse de l’impact de la conception de l’automobile sur la conception de l’habitat du futur. / The research field of this work is Industrial Engineering. This paper presents a study made to improve tomorrow’s automobile cabin habitability. It is focused on showing the influence on car-interior design by today’s home-interior design. The objective of this work is to propose a tool intended to help automobile designers to introduce home architectural construction principles into the car’s cabin design to improve its habitability. In our experimental phase we adopted principles of the method of analysis of the joint tendencies such as mappings and boards of categorization. This step showed that car designers have been increasingly using the home architectural construction principles on the car’s cabin conception design. Our research took into account the opinion of experts in both areas: architecture and design. In this way, we can be certain that the home and the automobile share the same criteria of habitability. We could also confirm that home architectural principles have a positive impact on the improvement of the habitability criteria in space design of the automobile’s cabin. This work opens a research line to analyze the influence of different areas in automobile design, such as aeronautics and electronics. This study can also show the inverse perspective of how car design can eventually have an impact on the future home design.

In the study of habitability of terrestrial exoplanets, both life-supporting conditions and the prevalence of transient life-threatening events need to be considered. One type of hazardous effect that has so far not received much attention is the thermal effect of a nearby active galactic nucleus (AGN), or in this particular case, the class of the AGN known as a quasar. In this work we investigate the thermal effect from a quasar by calculating the number of habitable terrestrial planets (HTP) in an elliptical or bulge-dominated galaxy, that goes extinct when exposed to the quasar radiation in a limited wavelength range. This is done by approximations and modelling along with pre-existing formulas and data from earlier publications. As a result, the influence by a quasar during the time span of quasar activity will have a less significant impact on the habitability in solar-type stellar systems than expected. Assuming tQSO = 108 yrs of quasar activity, results in the number of affected HTP, ≈ 1 × 105, 9 × 105 and 4 × 108 for isotropic spherical radiation and ≈ 1 × 106, 8 × 106 and 3 × 109 for a double-conical radiation. In terms of stellar mass fraction, ≈ 1.3%, 1.0%, 0.4% for isotropic radiation and ≈ 12.8%, 9.5%, 3.8% for conical, is affected. The results of this work are hoped to provide a rough estimation of the thermal impacts of a quasar on the habitability as well as to point out the most important parameters when considering this model. / I studier om beboeligheten på jordlika exoplaneter övervägs både förutsätningar för liv på planeten men även livshotande händelser i planetens närhet. En typ av farlig effekt som hit- intills inte fått mycket uppmärksamhet, är det termiska effekterna från en aktiv galaxkärna (AGN) eller som i detta fall, AGN-typen kvasar. I detta arbete studeras de termiska effekterna från en kvasar genom att beräkna antalet beboeliga jordlika exoplaneter (HTP) i en elliptisk eller bulge-dominerad galax, (bulge-centralförtätning), som blir obeboeliga då de utsätts för kvasarens strålning i ett begränsat våglängdsområde. Detta görs genom antaganden och modellering av redan befintliga formler och data från tidigare publikationer. Detta resulterar i en mindre inverkan av kvasaren på system kring sollika stjärnor än förväntat. Antaget tQSO =108 år av kvasar-aktivitet ger antal påverkade HTP, ≈ 1 × 105, 9 × 105 och 4 × 108 vid isotropisk strålning och 1 × 106, 8 × 106 och 3 × 109 vid dubbel-konisk formad strålning. Uttryckt i andel stjärnmassa motsvarar detta ≈ 1.3%, 1.0%, 0.4% för sfäriskt fall och ≈ 12.8%, 9.5%, 3.8% vid koniskt. Detta arbete hoppas kunna ge on grov uppfattning om kvasarens termiska effekter på beboligheten men även identifiera det mest betydande parametrarna i denna modell.

Certos ambientes subterrâneos da Terra possuem acumulados, naturalmente, compostos de radionuclídeos de longa vida, como 238U, 232Th 40K, próximo à presença de água líquida. O mesmo é esperado que aconteça em corpos planetários, no Sistema Solar, que possua quantidades apreciáveis de água. Nestes ambientes radioativos naturais, a radiólise da água produz espécies químicas e desequilíbrios químicos importantes para a vida. Apesar da proposta do decaimento radioativo como fonte alternativa de energia para sistemas vivos existir há mais de trinta anos, isto se mostrou realmente concreto após descoberta de um ecossistema peculiar cuja sobrevivência é dependente de espécies químicas produzidas por radiólise aquosa. Neste trabalho, avaliamos e quantificamos os desequilíbrios químicos gerados localmente pela radiólise aquosa e a possível contribuição destes para a emergência da vida, tendo como referência os estudos em ambientes de fontes hidrotermais alcalinas, consideradas promissores ambientes para esse evento. Também foram avaliados seus efeitos na habitabilidade de possíveis ambientes análogos na lua gelada Europa. Procuramos quantificar a diversidade química formada nessas condições e a associar aos desequilíbrios parâmetros termodinâmicos. As estimativas realizadas para ambientes radioativos na Terra primitiva apontaram para a similaridade entre o desequilíbrio causado por radiólise aquosa e o encontrado em fontes hidrotermais alcalinas. Confirmando e detalhando a análise preliminar que motivou o trabalho. Não obstante, considerando Europa, chegamos a valores de densidade de células do extremófilo Candidatus Desulforudis audaxviator que sobreviveriam em um conjunto de candidatos a análogos geológicos de possível ambiente radioativo na lua gelada. A partir deste estudo pudemos analisar o potencial para a emergência da vida e de protometabolismos nestes ambientes radioativos naturais na Terra primitiva, bem como levantar parâmetros mensuráveis para futuras missões espaciais que buscam vida ou habitabilidade em Europa. / Certain subterranean environments of the Earth has naturally accumulated compounds of longlived radionuclides, such as 238U, 232Th 40K, near the presence of liquid water. The same is estimated in wet planetary bodies in the Solar System. In these natural radioactive environments, water radiolysis produces chemical species and chemical disequilibria, which are important for life. Although the proposal of radioactive decay as an alternative source of energy for deep biospheres has existed for more than thirty years, this proved to be really feasible after the discovery of a peculiar ecosystem whose survivor is dependent on chemical species produced by water radiolysis. In this work, we evaluate and quantify the chemical disequilibria generated locally by water radiolysis and the possible contribution of these to the emergence of life, having as reference the studies alkaline hydrothermal vents, which is considered highly promising environment for this event. It is also evaluated their effects on the habitability of possible analogous environments on the Jupiter icy moon Europa. It was aimed to quantify the chemical diversity formed under these conditions and to calculate disequilibria using thermodynamic parameters. The estimates made for natural radioactive environments in early Earth pointed to the similarity between the disequilibrium caused by water radiolysis and those found in alkaline hydrothermal vents. What confirms and details the preliminary analysis that motivated this work. In addition, it was calculated values for cell density of the Candidatus Desulforudis audaxviator extremophile, that would survive in Europa comparable to the in situ analysis of some terrestrial radioactive environments, using a set of possible scenarios for possible local natural radioactive environments. From this study, we were able to analyze the potential for the emergence of life and protometabolisms in these natural radioactive environments in early Earth, as well as to provide measurable parameters for future space missions that seek for life or habitability in Europa.

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2015-03-30T20:12:08Z No. of bitstreams: 1 PauloRicardoPintoMoro..pdf: 28273254 bytes, checksum: 788ba8192d482cfe330570f0cf11628b (MD5) / Made available in DSpace on 2015-03-30T20:12:08Z (GMT). No. of bitstreams: 1 PauloRicardoPintoMoro..pdf: 28273254 bytes, checksum: 788ba8192d482cfe330570f0cf11628b (MD5) Previous issue date: 2011-05 / Banco Santander / Banespa / Este estudo visa contribuir para a qualificação do setor de habitação de interesse social na região do Vale dos Sinos, RS, avaliando sistemas construtivos e fatores de habitabilidade no projeto deste tipo de empreendimento praticado em São Leopoldo, RS. A história da produção social da moradia coloca o Estado como um dos principais atores nos processos implementados no Brasil desde a década de 30, embora essa atuação esteja sujeita a diversas críticas, tais como a baixa qualidade dos condomínios produzidos e o afastamento dos requisitos dos usuários. Esses dois elementos provocam inevitavelmente a necessidade de intervenções, geralmente desordenadas, bem como o aumento da perda da qualidade do produto. Neste estudo, são identificados e analisados alguns dos programas oficiais mais importantes, tais como os programas em uso desde o governo de Getúlio Vargas e seus sucessores até o governo de Luís Inácio Lula da Silva. Foram utilizados, como metodologia de pesquisa, instrumentos tais como levantamento de dados documentais, APO e entrevistas com usuários e demais atores dos programas estudados, bem como a observação sistêmica do pesquisador. O objetivo geral deste estudo é avaliar programas oficiais e conjuntos habitacionais destinados à habitação de interesse social, baseado em fatores de habitabilidade no contexto de São Leopoldo, RS. Como resultado desta discussão conclui-se que os modelos estudados apresentam características que atendem parcialmente as necessidades da população assistida pelos programas de habitação de interesse social na cidade de São Leopoldo e região de entorno. E, principalmente, que a inclusão de critérios de desempenho e sustentabilidade para a produção de habitações de interesse social devem contribuir significativamente para a melhoria do produto no segmento / This study aims to contribute to the qualification of the social housing sector on the Vale dos Sinos region, RS, investigating constructin systems and habitability factors of on projects of this kind of development practiced in São Leopoldo, RS. The social production history of housing put the State as one of the mainactors on the implemented process in Brazil since 30’s even though this action is submitted to several criticisms, such as low quality of produced houses groups and the removal user requirements. Inevitably, these two elements cause necessity of intervention, usually disordered and with further increase in product quality losses. In this study some of the main official models are identified and analyzed, in use since Getúlio Vargas’s government and his successor until the Luís Inácio Lula da Silva’s government . It has been used, as aresearch methodology, some instruments such as documentary data collection, APO and interviews with users and other stakeholders of the programs studied, as well as systemic observation of the researcher. The aim of this study is to evaluate public programs and housing condominium intended for social housing based on habitability factors in the context of Sao Leopoldo, RS. As a result of this discussion it was concluded that the models studied have characteristics that partially meet the needs of the population assisted by programs of social housing in the city of São Leopoldo and the surrounding region. And mainly that the inclusion of performance criteria and sustentability for the production of social housing must contribute significantly to the improvement of the product in the segment.

Esta dissertação de mestrado apresenta os resultados de uma pesquisa que buscou verificar se as normas vigentes no Brasil para os alojamentos dos tripulantes de navios mercantes são efetivas em propiciar boas condições de habitabilidade e segurança. O processo utilizado para esta verificação foi o de comparar tais normas com recomendações e determinações de diversas fontes. A opção por este objeto de pesquisa se justifica uma vez que atualmente, após mais de duas décadas de decadência da indústria naval e da frota mercante brasileiras, há um grande número de navios em construção. Além disso, a vida útil dos navios é de aproximadamente trinta anos, o que significa que a inadequação das normas segundo as quais são construídos implicaria em consequências de longo prazo e difíceis de serem revertidas, em função da complexidade dos navios. Por outro lado, a Organização Marítima Internacional e outras fontes citam o projeto dos alojamentos como um dos fatores que podem influenciar no aumento do número de casos e na intensidade da fadiga entre os tripulantes, com reflexos na incidência de erros humanos e, consequentemente, de acidentes marítimos. Um indicador da existência de deficiências na configuração dos espaços de alojamento é o número de acidentes pessoais neles ocorridos, relativamente alto quando comparado com o das áreas de trabalho e operação da embarcação, onde o risco de acidentes é consideravelmente maior. A confrontação das normas vigentes no Brasil com recomendações e determinações das diversas fontes consultadas evidenciou que estas admitem condições mais desfavoráveis do que as aceitas para embarcações destinadas a fins especiais e em navios de algumas marinhas de guerra. Ademais, sua análise revelou que não especificam os níveis considerados apropriados ao conforto térmico, acústico, iluminação e vibrações, o que indica que estão desatualizadas e aponta para a necessidade de sua revisão com base em estudos atuais. / This Master\'s dissertation presents the results of research which seeks to establish whether the prevailing standards for crew accommodation in merchant shipping in Brazil is effective in providing good conditions of habitability and safety. The verification process used was to compare such standards with recommendations and requirements from several different sources. The justification for this choice of research is that following more than two decades of decline in the shipbuilding sector and the Brazilian merchant navy, there are now a large number of ships once more under construction in indigenous shipyards. Since ships have a useful life of approximately thirty years, this means failure to adhere to construction standards would imply long term consequences, difficult to revert in the light of the complexity of vessels. Conversely, the International Maritime Organization as well as other sources, cites the onboard accommodation project as one of the factors that can impact the number of cases of fatigue and its intensity among crew members. This in turn is reflected in the level of human error and consequently, maritime accidents. One indicator of deficiencies in accommodation configuration is the number of personal accidents that occur in them, relatively high compared with onboard working and operational areas where risk of accidents is considerably greater. The comparison of the prevailing standards in Brazil with recommendations and requirements of several sources which have been consulted, revealed that these tolerate conditions which are less favorable than those acceptable in special purpose vessels and in the ships of some navies. Additionally, comparison showed that standards prevailing in Brazil fail to specify the levels deemed appropriate for thermal and acoustic comfort, lighting and vibration. The indication is that such are out-of-date - pointing to a need for review based on current studies.

In der vorliegenden Arbeit werden Methoden der Erdsystemanalyse auf die Untersuchung der Habitabilität terrestrischer Exoplaneten angewandt. Mit Hilfe eines parametrisierten Konvektionsmodells für die Erde wird die thermische Evolution von terrestrischen Planeten berechnet. Bei zunehmender Leuchtkraft des Zentralsterns wird über den globalen Karbonat-Silikat-Kreislauf das planetare Klima stabilisiert. Für eine photosynthetisch-aktive Biosphäre, die in einem bestimmten Temperaturbereich bei hinreichender CO2-Konzentration existieren kann, wird eine Überlebenspanne abgeschätzt. Der Abstandsbereich um einen Stern, in dem eine solche Biosphäre produktiv ist, wird als photosynthetisch-aktive habitable Zone (pHZ) definiert und berechnet. Der Zeitpunkt, zu dem die pHZ in einem extrasolaren Planetensystem endgültig verschwindet, ist die maximale Lebenspanne der Biosphäre. Für Supererden, massereiche terrestrische Planeten, ist sie umso länger, je massereicher der Planet ist und umso kürzer, je mehr er mit Kontinenten bedeckt ist. Für Supererden, die keine ausgeprägten Wasser- oder Landwelten sind, skaliert die maximale Lebenspanne mit der Planetenmasse mit einem Exponenten von 0,14. Um K- und M-Sterne ist die Überlebensspanne einer Biosphäre auf einem Planeten immer durch die maximale Lebensspanne bestimmt und nicht durch das Ende der Hauptreihenentwicklung des Zentralsterns limitiert. Das pHZ-Konzept wird auf das extrasolare Planetensystem Gliese 581 angewandt. Danach könnte die 8-Erdmassen-Supererde Gliese 581d habitabel sein. Basierend auf dem vorgestellten pHZ-Konzept wird erstmals die von Ward und Brownlee 1999 aufgestellte Rare-Earth-Hypothese für die Milchstraße quantifiziert. Diese Hypothese besagt, dass komplexes Leben im Universum vermutlich sehr selten ist, wohingegen primitives Leben weit verbreitet sein könnte. Unterschiedliche Temperatur- und CO2-Toleranzen sowie ein unterschiedlicher Einfluss auf die Verwitterung für komplexe und primitive Lebensformen führt zu unterschiedlichen Grenzen der pHZ und zu einer unterschiedlichen Abschätzung für die Anzahl der Planeten, die mit den entsprechenden Lebensformen besiedelt sein könnten. Dabei ergibt sich, dass komplex besiedelte Planeten heute etwa 100-mal seltener sein müssten als primitiv besiedelte. / In this thesis methods of Earth system analysis are applied to the investigation of the habitability of terrestrial exoplanets. With the help of parameterized convection models for the Earth the thermal evolution of terrestrial planets is calculated. Under increasing central star luminosity the global carbonate-silicate cycle stabilizes the planetary climate. The life span of a photosynthetic-active biosphere existing in a certain temperature interval under adequate CO2 concentration is estimated. The range of orbital distances within which such a biosphere is productive is defined as the photosynthetic-active habitable zone (pHZ) and is calculated. The maximum life span of the biosphere is the point in time when the pHZ of an extrasolar planetary system finally disappears. For super-Earths, i.e. massive terrestrial planets, it is as longer as more massive the planet is and as shorter as more the planet is covered with continents. For super-Earths, which are not pronounced land or water worlds, the maximum life span scales with the planetary mass with an exponent of 0.14. The life span of the biosphere on a planet around K- or M-stars is always determined by the maximum life span and not limited by the end of the main-sequence evolution of the central star. The pHZ approach is applied to the extrasolar planetary system Gliese 581. Accordingly the super-Earth of 8 Earth masses Gliese 581d could be habitable. Based on the presented pHZ concept the Rare Earth Hypothesis established by Ward and Brownlee 1999 is quantified for the Milky Way. This hypothesis claims that complex life may be very rare in the Universe while primitive life is likely common and widespread. Different temperature and CO2 tolerances as well as a different influence on weathering of complex and primitive life forms result different boundaries of the pHZ and a different estimate of the number of planets potentially harboring these different life forms. It arises that planets with complex life might be 100 times rarer than primitive life bearing planets.