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Habitability and Biosignatures

Is there life on other planets? First, we have to identify the most promising planets for life to evolve. Life as we know it needs liquid water, which requires a certain temperature range on the planetary surface. The evolution of the surface temperature can be modeled accounting for the star type, the solar distance, and greenhouse gases in the atmosphere. If a potentially habitable planet is detected, we can focus on possible biosignatures, as for example the existence of oxygen and methane in the atmosphere. I am particularly interested in biosignatures that are a result of the interplay between life and the solid planet. What is the role of life in the evolution of the Earth? How would our planet look like without life?

Feedback Loops and the Interior Evolution of the Earth

I am particularly fascinated by feedback loops in the Earth's evolution. Which parameters determine the behavior of the whole system? Which parameters are not really important? Feedback loops can couple the evolutions of the Earth's interior, crust, and atmosphere. Water and carbon dioxide are degassed at mid-ocean ridges, transported within the oceans and atmosphere, and subducted within sediments and minerals back into the mantle at subduction zones. Water in the Earth's mantle reduces the viscosity, thereby speeding up the convection rate. CO2 is greenhouse gas in the atmosphere with a strong effect on the surface temperature. How would the system work if, for example, the Earth would surround the sun at the orbit of Venus? How would the system without land plants that enhance the weathering rate and thereby the rates of sedimentation and volatile subduction? read more

Continental Growth and Implications for Exoplanets

Geochemical studies show that most of the Earth's continental volume was already present billions of years ago. However, this does not imply that continents are not produced anymore. Rather, there is a continuous equilibrium between continental production and erosion. How can we explain that this equilibrium did not change much over the past billion years despite the cooling of Earth's mantle? What does this mean for the continental cycle on exoplanets? read more