Habitability of Super-Earths: Gliese 581c and 581d

The unexpected diversity of exoplanets includes a growing number of super-Earth planets, i.e., exoplanets with masses smaller than 10 Earth masses. Unlike the larger exoplanets previously found, these smaller planets are more likely to have a similar chemical and mineralogical composition to the Earth. We present a thermal evolution model for super-Earth planets to identify the sources and sinks of atmospheric carbon dioxide. The photosynthesis-sustaining habitable zone (pHZ) is determined by the limits of biological productivity on the planetary surface. We apply our model to calculate the habitability of the two super-Earths in the Gliese 581 system. The super-Earth Gl 581c is clearly outside the pHZ, while Gl 581d is at the outer edge of the pHZ. Therefore it could at least harbor some primitive forms of life.Comment: 3 pages, 1 figure; submitted to: Exoplanets: Detection, Formation and Dynamics, IAU Symposium 249, eds. Y.-S. Sun, S. Ferraz-Mello, and J.-L. Zhou (Cambridge: Cambridge University Press

Habitability of the Goldilocks Planet Gliese 581g: Results from Geodynamic Models

Aims: In 2010, detailed observations have been published that seem to indicate another super-Earth planet in the system of Gliese 581 located in the midst of the stellar climatological habitable zone. The mass of the planet, known as Gl 581g, has been estimated to be between 3.1 and 4.3 Earth masses. In this study, we investigate the habitability of Gl 581g based on a previously used concept that explores its long-term possibility of photosynthetic biomass production, which has already been used to gauge the principal possibility of life regarding the super-Earths Gl 581c and Gl 581d. Methods: A thermal evolution model for super-Earths is used to calculate the sources and sinks of atmospheric carbon dioxide. The habitable zone is determined by the limits of photosynthetic biological productivity on the planetary surface. Models with different ratios of land / ocean coverage are pursued. Results: The maximum time span for habitable conditions is attained for water worlds at a position of about 0.14+/-0.015 AU, which deviates by just a few percent (depending on the adopted stellar luminosity) from the actual position of Gl 581g, an estimate that does however not reflect systematic uncertainties inherent in our model. Therefore, in the framework of our model an almost perfect Goldilock position is realized. The existence of habitability is found to critically depend on the relative planetary continental area, lending a considerable advantage to the possibility of life if Gl 581g's ocean coverage is relatively high. Conclusions: Our results are a further step toward identifying the possibility of life beyond the Solar System, especially concerning super-Earth planets, which appear to be more abundant than previously surmised.Comment: 5 pages, 3 figures, 1 table; in pres

Small towns as interfaces for interaction, exchange and transition in Vietnam

"Kleinstädte stellen eine entscheidende Verbindung zwischen städtischem und ländlichem Raum dar und sind somit wichtig für das Verständnis regionaler Entwicklungsprozesse. Hier verspricht eine integrative Analyse des Zusammenhangs zwischen lokalen Interaktions- und Verhandlungsprozessen und überregionalen Prozessen und Strukturen aufschlussreiche Einsichten. Die Analyse verwendet das Konzept der 'gesellschaftliche Schnittstelle' (social interface) in Bezug auf Begegnungen zwischen Akteuren unterschiedlicher Bereiche und Ebenen innerhalb von Kleinstädten. Dieser Ansatz wird beispielhaft anhand von Interaktionsprozessen entlang politischer und ökonomischer Schnittstellen in vietnamesischen Kleinstädten skizziert. Dieser Ansatz bedarf noch einer Überprüfung und Ausarbeitung in der Praxis, verspricht aber eine komplexere und vollständigere Erfassung aktueller Entwicklungstrends." (Autorenreferat)"Small towns present a critical link between urban systems and rural landscapes and are thus relevant for the understanding of regional development processes. In this context, an integrative analysis of the dynamics of interaction and negotiation on the local level and their correlation with higher-level structures and processes is insightful. The analysis draws on the concept of the social interface which is here applied to encounters between actors of various fields and levels within the arena of the small town. This approach is exemplified by an outline of processes of negotiation and mediation along political and economic interfaces in small Vietnamese towns. While the approach remains to be verified and elaborated in practice, it promises to provide a more complex and holistic view of current development trends." (author's abstract

The habitability of super-Earths in Gliese 581

Aims: The planetary system around the M star Gliese 581 consists of a hot Neptune (Gl 581b) and two super-Earths (Gl 581c and Gl 581d). The habitability of this system with respect to the super-Earths is investigated following a concept that studies the long-term possibility of photosynthetic biomass production on a dynamically active planet. Methods: A thermal evolution model for a super-Earth is used to calculate the sources and sinks of atmospheric carbon dioxide. The habitable zone is determined by the limits of biological productivity on the planetary surface. Models with different ratios of land / ocean coverage are investigated. Results: The super-Earth Gl 581c is clearly outside the habitable zone, since it is too close to the star. In contrast, Gl 581d is a tidally locked habitable super-Earth near the outer edge of the habitable zone. Despite the adverse conditions on this planet, at least some primitive forms of life may be able to exist on its surface.Therefore, Gl 581d is an interesting target for the planned TPF/Darwin missions to search for biomarkers in planetary atmospheres.Comment: 6 pages, 4 figures, 2 table

The fate of Earth’s ocean

Questions of how water arrived on the Earth’s surface, how much water is contained in the Earth system as a whole, and how much water will be available in the future in the surface reservoirs are of central importance to our understanding of the Earth. To answer the question about the fate of the Earth’s ocean, one has to study the global water cycle under conditions of internal and external forcing processes. Modern estimates suggest that the transport of water to the surface is five times smaller than water movement to the mantle, so that the Earth will lose all its sea-water in one billion years from now. This straightforward extrapolation of subduction-zone fluxes into the future seems doubtful. Using a geophysical modelling approach it was found that only 27% of the modern ocean will be subducted in one billion years. Internal feedbacks will not be the cause of the ocean drying out. Instead, the drying up of surface reservoirs in the future will be due to the increase in temperature caused by a maturing Sun connected to hydrogen escape to outer space.</p> <p style='line-height: 20px;'><b>Keywords: </b>Surface water reservoir, water fluxes, regassing, degassing, global water cycl

Causes and timing of future biosphere extinctions

We present a minimal model for the global carbon cycle of the Earth containing the reservoirs mantle, ocean floor, continental crust, biosphere, and the kerogen, as well as the combined ocean and atmosphere reservoir. The model is specified by introducing three different types of biosphere: procaryotes, eucaryotes, and complex multicellular life. During the entire existence of the biosphere procaryotes are always present. 2 Gyr ago eucaryotic life first appears. The emergence of complex multicellular life is connected with an explosive increase in biomass and a strong decrease in Cambrian global surface temperature at about 0.54 Gyr ago. In the long-term future the three types of biosphere will die out in reverse sequence of their appearance. We show that there is no evidence for an implosion-like extinction in contrast to the Cambrian explosion. In dependence of their temperature tolerance complex multicellular life and eucaryotes become extinct in about 0.8–1.2 Gyr and 1.3–1.5 Gyr, respectively. The ultimate life span of the biosphere is defined by the extinction of procaryotes in about 1.6 Gyr

Генезис социальной инженерии в контексте междисциплинарности

Трансформация научного знания в условиях междисциплинарности, изменение парадигмы инженерного мышления по новому ставят проблему социальной инженерии. Ее решение требует обращения к истокам социальной инженерии. Проанализирован генезис и развитие социальной инженерии. Выявлено соотношение науки и дисциплины. Показана роль социальной инженерии в системе междисциплинарности

No size fits all - Exploring Entrepreneurship Measurement using Big Data, rare Events and Ecosystems

Entrepreneurship is one major factor influencing the world we live in. At that, the relationship between entrepreneurship and this world is an interdependent one and entrepreneurial activity in any given territory is an inherently economic geographical process. As a highly multidisciplinary research field, entrepreneurship has been analysed for decades, yet as the world progresses, the entrepreneurial phenomena evolve as well. Sophisticated research needs outstanding data. Plenty manifestations of entrepreneurship are not or not sufficiently covered by such data. There is a need to explore new methods and approaches for data on entrepreneurship to tackle unsolved issues and address newly developing phenomena. Some entrepreneurial events are so rare it is difficult to get quantitative data on them, making them dominated by qualitative case studies. Moreover, other areas in entrepreneurship are so complex, that reliable comparable data need a broad and coordinated approach. This thesis addresses these issues as such, that it contributes to a more complete empirical data body, and it expands the understanding how bespoke methodology leads to phenomenon specific empirical data and ultimately to place based policies and is thus overall advancing entrepreneurship research

Self-stabilization of the biosphere under global change: A tutorial geophysiological approach

A 2-dimensional extension of the simple Lovelock-Watson model for geosphere-biosphere feed-back is introduced and discussed. Our enriched version also takes into account various pertinent physical, biological, and civilisatory processes like lateral heat transport, species competition, mutation, germination, and habitat fragmentation. The model is used as a caricature of the Earth System, which allows potential response mechanisms of the biosphere to environmental stress (as generated, e.g., by global warming or anthropogenic land-cover change) to be investigated qualitatively. Based on a cellular automaton representation of the system, extensive calculations are performed. They reveal a number of remarkable and, partially, counter-intuitive phenomena: our model biosphere is able to control almost perfectly the geophysical conditions for its own existence. If the environmental stress exceeds certain thresholds, however, life breaks down on the artificial planet via a first-order phase transition, i.e., in a non-reversible way. There is a close connection between self-stabilizing capacity, biodiversity and geometry of habitat fragmentation. It turns out, in particular, that unrestricted Darwinian competition, which reduces the number of co-existing species, is the best guarantee for survival of the artificial ecosphere as a whole