Vorträge, Seminare, Ereignisse

Abstract
The emergence of life on Earth required reducing conditions\; however, the geological record suggests an early oxidizing atmosphere. How, then, was the primordial soup prepared? How can the Miller-Urey experiment be saved? We address these questions by extending a photochemical model of the Hadean atmosphere to evaluate the impact of different sources of reducing gases. These sources include volcanic serpentinization and the bombardment of enstatite and carbonaceous meteorites during the Late Heavy Bombardment. By coupling this model with a wet-dry cycling model, we can estimate the concentrations of key prebiotic molecules in Darwinian ponds on early Earth. Our results demonstrate that a CO₂-rich atmosphere can be reduced by global serpentinization alone. This yields key building blocks of life at millimolar concentrations in the modeled ponds. These concentration levels are sufficient for nucleotide synthesis, producing the monomers of RNA. These findings suggest that RNA could have emerged soon after Earth became habitable and/or reappeared later during the Hadean-Archean transition.

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Gaia, developed and operated by the European Space Agency, was launched in 2013, and operated until January 2025. It's creating a revolutionary six-dimensional map of our Galaxy by measuring the accurate distances and space motions of some three billion stars. While the measurement of star positions has a very long history, stretching back more than 2000 years, Gaia's accuracies exploit the numerous advantages of measurements made from above the Earth's atmosphere. Absolute positional accuracies of order 10 micro-arcsec can register stellar motions that would require more than 10,000 years to be discerned on the ground.  This is providing a major advance in understanding stellar evolution, and in unravelling the composition, structure, and history of our Galaxy's formation. I will not focus on the technical details, but provide a "big picture" of Gaia's scientific advances.

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