Carbonaceous meteorites: source or substrate for life's origin on Earth?

Abstract

Carbonaceous meteorites are relics of ancient parent bodies from the time of formation of our solar system, approximately 4.5 billion years ago. They provide the best direct evidence for the organic inventory of the solar system prior to the evolution of habitable conditions for life on Earth and/or Mars and are often speculated as being a possible source of the organic matter from which life eventually emerged. Whether the residual organic matter in carbonaceous meteorites was derived in part from ancient extraterrestrial organisms or was entirely prebiotic in origin remains the topic of lively debate. Clearly, however, impact histories during the early stages of planet development logically point to some type of involvement of this material with respect to life's proliferation, either as a source or substrate. The compositions of CI and CM cabonaceous meteorites are assessed with respect to these two alternative scenarios.