Interplanetary dust particles , organic

Flynn G. J., Keller F. P., Feser M., Wirick S. and Jacobsen C. (2003). The origin of organic matter in the solar system evidence from the interplanetary dust particles. Geochimica et Cosmochimica Acta 67 4791. 

Piazzarello, S., Cooper, G. W. and Flynn, G. J. (2006) The nature and distribution of the organic material in carbonaceous chondrites and interplanetary dust particles. In Meteorites and the Early Solar System II, eds. Lauretta, D. S. and McSween, H. Y., Jr. Tucson University of Arizona Press, pp. 625-651. A comprehensive, up-to-date review of organic matter in carbonaceous chondrites, but not for the faint-hearted. 

The importance of exogenous delivery of organic matter to the early Earth is critically dependent on the survivability of organic compounds during the delivery process. It is presently unclear exactly how much organic material would escape destruction during asteroid, comet and interplanetary dust particle infall to the Earth s surface. 

Marttette M, Duprat J, Engrand C, Gotmelle M, Kurat G, Matrajt G, Toppani A (2000) Accretion of neon, organics, CO2, nitrogen and water from large interplanetary dust particles on the early Earth. Planet Space Sci 48 1117-1137... 

Calculations also showed that about 4 Ga ago, more carbon was delivered to Earth in less than a few million years by interplanetary dust particles than the current amount of organic carbon in the biosphere, or about... 

Organic-rich extraterrestrial samples such as meteorites, micrometeorites, interplanetary dust particles (IDPs) and samples returned by spacecraft provide a unique record of the chemical processes in the early solar system and in the interstellar medium. In particular, detailed structural and isotopic analyses of carbonaceous meteorites have revealed a rich organic inventory and provided evidence of the synthesis of complex organic molecules in the interstellar medium and on the asteroidal parent bodies of meteorites [1,2], The organic matter in carbonaceous meteorites is present at levels of up to 5% and can be divided into solvent-soluble (l%-25%) and insoluble (75%-99%) fractions, the former characterized by considerable structural, isomeric, and isotopic diversity [2,3], and the latter characterized by a high molecular weight and complex aromatic network [4]. 

It is reasonable to consider the assumption that life began, somehow, among one of the mixtures of small organic molecules that are produced by abiotic processes. The only natural examples in hand today are the components of meteorites that have fallen to Earth (see Section 5.2.1) and particles returned by the Stardust mission. Spectroscopy has also yielded partial lists of the organic molecules in interstellar space and interplanetary dust clouds. 

Meteorites from the asteroid belt are a potential source of some of the purine bases present in RNA. As asteroids travel in their orbits between Mars and Jupiter they collide with each other and pieces are broken off that vary in size from large bodies (potential meteorites) to dust particles. If the energy of the collision is great enough, this material is propelled out of its orbit into the interplanetary medium and some of the material eventually reaches the Earth. Approximately 10 kg of asteroidal material reached the primitive Earth s surface (6). This corresponds to a layer of material weighing 2x10 kg/m if spread uniformly over the surface of the Earth. The carbon content of the soluble organics present (1%) is equivalent to a layer of carbon compounds 25 m thick on the primitive Earth. Since meteorites contain about 1 ppm of purines and pyrimidines, then about lO kg of these compounds were on the primitive Earth. 

The analysis of cometary observations suggests the existence of very fluffy dust aggregates. Differences are observed in the light-scattering properties, e.g. stracture of the comae, polarization phase curves maxima and minima, polarization wavelength dependence. They could be a clue to the temporal evolution of the physical properties of the dust particles, with collisional processes as well as evaporation of icy mantles and organic compoimds. Table 1 presents some polarization properties of dust particles in comets, asteroids, in the interplanetary dust cloud, and on Mars, as retrieved by remote sensing. 

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