'Accretion' and chemistry along the trajectory of 'shooting stars'

Details 'Accretion' and chemistry along the trajectory of 'shooting stars' 'Accretion' and chemistry along the trajectory of 'shooting stars'

Jul 1994

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994metic..29r.498m&link_type=abstract

Meteoritics (ISSN 0026-1114), vol. 29, no. 4, p. 498-499

Other

Bolides, Chemical Reactions, Meteor Trails, Micrometeoroids, Temperature Effects, Abundance, Gravitational Effects, Isotopic Enrichment, Transmission Electron Microscopy

Scientific paper

The trajectories of micrometeorites in the Earth's atmosphere include a 'hot' shooting star segment, then a complex gravitational settling in the 'E' layer and the stratosphere, and, for two-thirds of the micrometeorites, a 'terminal' fall into sea water. Both the tiny stratospheric Interplanetary Dust Particles (IDPs) and the larger Antarctic micrometeorites (MMs) show evidence for the accretion of various components from the Earth's atmosphere. In collaboration with R. Harvey, J. Cragin, and S. Taylor, we have extracted cosmic spherules and MMs from a approximately equal 50-kg block of Antarctic ice. The observations support the important role of micrometeorites in scavenging a variety of atmospheric components. Concerning chemical reactions taking place along the tracks of 'shooting stars,' we can only report some 'structural' evidence, resulting from our analytical Transmission Electron Microscopy (TEM) observations of either micrometer-sized crushed grains or ultramicrotomed sections of MMs. Our observations indicate that they can be assimilated to 'catalyzing-aggregates.' We are engaged in various types of simulation experiments to assess the catalytic activity of micrometeorites, to check in particular whether they might have functioned as 'chondritic' chemical reactors on the early Earth to synthetize prebiotic molecules, either upon their own hydrolysis in early seas, or along their shooting-star trajectory in the atmosphere. In this last context, a difficult experiment consists of levitating MMs in reactive molecular gases, and detecting reaction products. If these difficult experiments do succeed they should open 'new horizons.' Indeed this 'astrochemistry of shooting stars' could also be effective in other types of atmospheres, and even in the strong approximately 100 km/hr 'blizzard' that ejects cometary micrometeorites from their parent nuclei of 'frozen mud.'

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