Conel Alexander (Department of Terrestrial Magnetism - Carnegie Institution of Washington DC) Tuesday May 27th - 11am IPAG Seminar Room - IPAG
Two prominent models, the so-called Grand Tack and Nice models, were designed to explain the small mass of Mars and the current orbital configuration of the planets and planetesimals in the Solar System, respectively. Both invoke episodes of dramatic orbital migration of the giant planets. In the process, planetesimals from the outer Solar System are scattered into the terrestrial planet region. These presumably icy, or comet-like, bodies are potent potential sources of volatiles for the Earth and the other rocky planets. One of the predictions of both models is that some of these outer Solar System planetesimals would have been emplaced into the asteroid belt, particularly the outer part. The outer asteroid belt is dominated by C complex asteroids that, based on spectroscopic similarities, are thought to be the parent bodies of the primitive carbonaceous chondrite meteorites. The carbonaceous chondrites are also one of the leading candidates for the sources of Earth’s volatiles, including prebiotic organic molecules. The carbonaceous chondrites can potentially be used to test these two important models. To determine whether carbonaceous chondrites could be from the outer Solar System, I will compare the properties of the carbonaceous chondrites (mineralogy, petrology, and O and H isotopes) with those of comets, the only outer Solar System objects for which we have samples.
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