Meteoritic organic matter

The principal focus of this review is on the analysis of the organic matter in the Murchison CM2 chondrite, together with data from other meteorites, where it can be shown that they have not been compromised by terrestrial contamination. It primarily covers work undertaken since 1980, a period that has seen the increasing use of stable-isotopic techniques to elucidate the sources of meteoritic organic matter, improved methods to study the structure of organic matter such as NMR, and the first in situ examinations of organic matter in meteorites these approaches have provided significant advances in our... 

Hypotheses for the origin of meteoritic organic matter must account for its molecular and isotopic composition and be consistent with models of meteorite petrogenesis consequently, a number of potential environments have been considered (Table 9). Until the early 1990s, the favored hypothesis involved the catalytic hydrogenation of CO in the solar nebula. However, a characteristic of such catalytic reactions is their structural selectivity. FTT synthesis, in particular, produces a structurally selective suite of hydrocarbons and other compounds that, initially, were believed to... 

Table 9 Sources and processes potentially involved in the production of meteoritic organic matter.

Becker L. et al. (1999). The origin of organic matter in the Martian meteorite ALH84001. 

Kerridge JF (1983) Isotopic composition of carbonaceous-chondrite kerogen evidence for an interstellar origin of organic matter in meteorites. Earth Planet Sci Lett 64 186-200 Kerridge JF, Haymon RM, Kastner M (1983) Sulfur isotope systematics at the 21°N site. East Pacific Rise. Earth Planet Sci Lett 66 91-100... 

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. 

Especially large amounts of the uncontaminated CM chondrites Murchison and Tagish Lake have been available since their falls in 1969 and 2000, respectively, and most modem research on extraterrestrial organic matter has focused on these meteorites. Considerable research has also been done on organic matter in the Orgueil Cl chondrite, but this meteorite has been contaminated during its nearly 150 years on Earth. 

In this chapter, we only briefly consider ices, focusing on their relationship to organic matter and noble gases in the ISM and in the solar nebula. Our understanding of ices is rudimentary because, unlike meteorites, ices have been studied only by remote sensing. 

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. 

Busemann, H., Young, A. F., Alexander, . M. O D. el al. (2006) Interstellar chemistry recorded in organic matter from primitive meteorites. Science, 312, 727-730. 

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. 

Beginnings of cosmochemistry (and geochemistry) Philosophical foundations Meteorites and microscopy Spectroscopy and the compositions of stars Solar system element abundances Isotopes and nuclear physics Space exploration and samples from other worlds New sources of extraterrestrial materials Organic matter and extraterrestrial life ... 

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