Study of the Origin, Evolution and Distribution of Life with Emphasis on Exobiology Experiments in Earth Orbit

Abstract

Publisher Summary This chapter presents an overview of those aspects of exobiology that can be investigated by experiments in earth orbit. The chapter focuses on the processes of organic chemical evolution in different bodies of solar system and beyond, and discusses the relevance of the organic compounds to the emergence of life on Earth. The possibility of interplanetary distribution of life is reviewed, and the experimental data testing this hypothesis is presented. In the chain of evolutionary steps towards the emergence of life, prebiotic chemical evolution is crucial. For the supply of organic molecules on the primitive earth, two plausible pathways are considered: terrestrial production of organics and import of extraterrestrial organic matter. In experiments simulating the putative conditions existing on the early earth, nearly all building blocks of life are synthesized, such as amino acids, purines, pyrimidines, and lipid-like compounds. However, in a non-reducing atmosphere, nitrogen containing compounds are unstable. Therefore, incoming extraterrestrial material may be considered as an essential source of organics on the primitive earth.