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M. Bertrand (CNRS-Orleans), S. van der Gaast (Netherlands Inst. Sea Res.), F. Vilas, F. Horz, G. Barnes (NASA JSC), B. Barbier, A. Chabin, A. Braak, A. Westall (CNRS-Orleans)
Our study concerns the hypothesis that prebiotic organic matter, present on Earth, was synthesized in the interstellar environment, and then imported to Earth by the meteorites or micrometeorites. We are particularly concerned with the formation and fate of amino acids. We have already shown that amino acid synthesis is possible inside cometary grains under interstellar environment conditions (Munoz Caro, et al. Nature 416, 403 (2002).). We are now interested in the effects of space conditions and meteoritic impact on these amino acids (Barbier B., et al. Planet. Space Sci. 46, 391 (1998), Barbier B., et al. , Planet. Space Sci. 50, 353 (2002) ; Boillot F., et al. Origins of Life and Evol. Biosphere 32, 359 (2002)). Most of the extraterrestrial organic molecules known today have been identified in carbonaceous chondrite meteorites. One of the components of these meteorites is a clay with a composition close to that of saponite. Thus, in order to study the effects of meteoritic impact on amino acids, three amino acids (alanine, glycine, and b-alanine) were mixed with 0,275 mg saponite clay to simulate a carbonaceous chondrite meteorite. These three amino acids were identified in the Murchison meteorite, and two of them (Gly and Ala) are used in biological systems. A pressure of 15 GPa, simulating a meteorite impact with a velocity of 1.2 km/sec was applied to this artificial meteorite at the NASA Johnson Space Center Experimental Impact Laboratory. The sample extracts show a good preservation of the amino acids : 34% of glycine, about 46% of D-alanine and about 20% of b-alanine were preserved. Another experiment has been carried out using different amino-acids and higher pressures. We are now analyzing the samples.
The preparation and the analysis of samples were carried out in Orléans (France) at the Molecular Biophysics Center.
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.