Organic matter comets

Star formation and the formation of star systems with planets around them, constantly takes place in dense interstellar clouds. The material present in these clouds is incorporated into the objects that are formed during this process. Pristine or slightly altered organic matter from the cloud from which our solar-system was formed is therefore present in the most primitive objects in the solar system comets, asteroids, and outer solar-system satellites. Pieces of asteroids (and perhaps comets) can be investigated with regards to these components through the analyses of meteorites (and eventually in samples returned from these bodies by spacecraft) in laboratories on Earth. The infall of asteroid and comet material from space may have contributed to the inventory of organic compounds on primordial Earth. 

We have now set the stage for the next two chapters - anhydrous planetesimals and ice-bearing comets and asteroids. These objects contain the organic matter, noble gases, and sometimes ices that we have just learned about, and they provide us with the best record of primitive materials in the solar system. 

Gilmour, I. (2004) Structural and isotopic analysis of organic matter in carbonaceous chondrites. In Treatise on Geochemistry, Vol. 1. Meteorites, Comets, and Planets, ed. Davis, A. M. Oxford Elsevier, pp. 269-290. 

The organic matter in these comet grains has also been characterized (Sandford et al.,... 

Hydrogen in these particles is correlated with carbon and is presumed to occur in organic matter. Analyses of the isotopic composition of hydrogen (McKeegan et al., 2006) show D/H enrichments (Fig. 12.12). The D/H ratios overlap those of H20 in comets but are well below those determined for organic matter in CP IDPs. Measurements of nitrogen isotopes show 15N enhancements, suggesting an interstellar contribution. 

Measured D/H ratios in five bulk Stardust particles (black dots sizes represent relative particle sizes), and in micron-size subareas in one particle (open circles enclosed by oval) measured by ion microprobe. The particle compositions overlap D/H ratios in comets, IDPs, and the insoluble organic matter in chondrites. Modified from McKeegan et al. (2006). 

Kennicutt II, M.C., and Comet, P.A. (1992) research of sediment hydrocarbon sources multiparameter approaches. In Organic Matter Productivity, Accumulation, and Preservation in Recent and Ancient Sediments (Whelan, J.K., and Farrington, I.K., eds.), pp. 308-338, Columbia University Press, New York. 

Cronin J. R., PizzareUo S., and Cruikshank D. P. (1988) Organic matter in carbonaceous chondrites, planetary satellites, asteroids and comets. In Meteorites and the Early Solar System (eds. J. F. Kerridge and M. S. Matthews). University of Arizona Press, Tucson, pp. 819-857. 

Anders, E. (1989). Pre-biotic organic matter from comets and asteroids. Nature, 342, 255-7. 

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. 

Gihnour, L Structural and isotopic analysis of organic matter in carbonaceaous chondrites. In Meteorites, Comets and Planets. Treatise on Geochemistry Davis, A.M. Elsevier Oxford, U.K., 2005 Volume 1, pp. 269—290. 

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