Carbonaceous chondrites: tracers of the prebiotic chemical evolution of the Solar System

The astrobiological relevance of carbonaceous chondrites is reviewed. It is argued that the primitive meteorites called carbonaceous chondrites provide a unique source of information about the materials and conditions in the Solar System during the earliest phases of its history, and its subsequent evolution. Presolar dust grains extracted from the carbonaceous chondrites provide direct information on the previous generations of stars that provided the materials present for planet formation. The organic material found in carbonaceous chondrites consist of amino acids, carboxylic acids and sugar derivatives. Part of the amino acids found show L-enantiomeric excesses, which indicates that homochirality on Earth could be a direct result of input from meteoritic material to the early Earth. Received 15 March 2005, accepted 25 June 2005