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Seminare am MPS

11008 1504710148

MPS Seminar: An observational study on the generation and propagation of intensity disturbances in solar polar coronal holes (L. Xia)

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11080 1505741525

MPS Seminar: On the Origin of Life, Darwin`s Warm Little Pond revisited and implications for the search for life in the solar system (M. J. Van Kranendonk)

Darwin first postulated - 145 years ago - that life might have originated in “…some warm little pond with all sorts of ammonia and phosphoric salts, light, heat, electricity, etc. present, that a protein compound was chemically formed, ready to undergo still more complex changes…”. However, the 1970’s discovery of deep sea black smokers and their rich vent fauna, together with evidence from the mitochondrial tree of life, led to the currently prevailing view that life got started at deep sea vents. But it turns out that the energy required for polymerisation of organic molecules from simple amino acids comes from expelling a water molecule. In addition, the cytoplasm of cells from all three branches of life have K+/Na+ ratios more aligned with fresh water than seawater, and that certain key elements (B, Zn, Mn) required as catalysts for polymerisation are hard to concentrate in the uniform marine reservoir. Thus, it turns out that the oceans, or any permanently wet environment, are not suitable for prebiotic chemistry and thus a land-based environment undergoing wet-dry cycles is required for an Origin of Life setting. But what kind of environment? Previous authors have suggested a desert with seasonal rain, or a river flowing over komatiitic crust as possible sites for the Origin of Life. But these cold-water environments lack the capacity for compositional complexity and highly reactive interfaces. Recent discoveries from an ancient analogue site in Western Australia’s Pilbara region provide support for an Origin of Life in terrestrial hot springs. The 3.48 Ga Dresser Formation is well known as hosting some of Earth’s oldest convincing evidence of life (stromatolites, fractionated stable isotopes, and putative microbial remains), all within an active volcanic caldera characterised by voluminous hydrothermal fluid circulation. Previously, the depositional environment was considered as shallow marine, but the recent discovery of geyserite and other siliceous sinter deposits containing biosignatures and spatially closely associated with stromatolites, point to a thriving terrestrial hot spring setting with wet-dry cycles. A parallel, key, discovery is of concentrations of the critical elements required for prebiotic chemistry (B, Zn, and Mn), which arise from hot water-rock interactions. These discoveries are leading to a developing model for the Origin of Life in terrestrial hot spring fields, and have implications for Astrobiology and the search for life elsewhere in the Solar System. On Mars, we advocate for the Columbia Hills site that has known hotspring deposits identified from a previous rover mission. Further afield, advocates for exploration of the icy water moons of Saturn and Jupiter face the problem of a permanently wet environment that appears not to be favourable for life to develop. [mehr]

11015 1504870405

Planetary Group Seminar: Comet 67P/Churyumov-Gerasimenko in the eyes of a geologist (R. El-Maarry)

The Rosetta mission to comet 67P/Churyumov-Gerasimenko has expanded the field of cometary science from the realm of Earth-based astronomers to include that of planetary scientists and geologists. The unique capabilities of the mission in being able to provide some of the highest resolution images we have ever acquired from a space mission in addition to being the first to put a lander on the surface of a comet and escort the comet itself on its journey around the Sun for more than 2 years has given has given us unprecedented insights into cometary nuclei morphology and the unique processes that shape their landscapes. In this talk, I will try to give an overview of the mission’s activities, and highlight the surface morphology of comet 67P with its diverse, and at times truly bizarre, landscape, as well as an update on our understanding of how these landscape form, and evolve, with time. [mehr]

10254 1500894893

Planetary Group Seminar: Soft Protons in the Magnetosphere focused by X-ray Telescopes (F. Gastadello)

One of the major and unfortunately unforeseen sources of background for the current generation of X-ray telescopes, in particular the ESA X-ray satellite XMM-Newton, is due to soft (few tens-hundreds of keV) protons concentrated by the X-ray mirrors. The observing time lost is 40% in the case of XMM, affecting all the major broad science goals of this observatory, ranging from cosmology to astrophysics of neutron stars and black holes. The soft proton background can impact dramatically future large X-ray missions such as the ESA planned Athena mission. We will review the still poor understanding of the physical process at work and the connection with the magnetospheric population and acceleration sites originating the phenomenon. [mehr]

11020 1504870205

Planetary Group Seminar: Experimental and numerical analysis of MHD effects in weakely ionized space relevant plasmas (G. Herdrich)

Georg Herdrich is head of the Plasma Wind Tunnels and Electric Propulsion department of the Institute of Space Systems (IRS) at the university of Stuttgart. The department is specialized on electric propulsion systems, plasma measurement systems and test benches for reentry simulations as well as test branches for Interial electrostatic confinement devices for small electron and ion jets. In his talk he will give an overview of the IRS activities, with a focus on the experimental and numerical work on MHD effects in weakly ionized plasmas, which i.a. present on the lunar surface. [mehr]

10368 1498221374

MPS Seminar: Reconnection and shock wave acceleration in astrophysical plasmas (T. Hoshino)

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