Current Advances in Prebiotic Chemistry Under Space Conditions

The presence of organic molecules in meteorites clearly indicates the occurrence of a large panel of chemical reactions in space conditions. The scenarios in which these transformations take place are diverse and fascinating: proto-stellar nebulae, dense or rarefied clouds of interstellar and cosmic dust particles, comets, meteorites, proto-planets and asteroids. High energy particles (cosmic rays and solar winds), heat, electromagnetic radiations, and radioactive decays continuously interact with simple chemical precursors to yield new complex derivatives. Some of these reactions are more relevant than others in the process of origin of life. The prebiotic chemistry in space conditions finally determines the synthesis of molecules that may play a key role in the organization of the first genetic and metabolic systems. Once synthesized some molecules can be transported through the universe until habitable planets. The description of the full set of these reactions is extremely complex and necessarily incomplete. In this review, some relevant prebiotic processes in space conditions are described with particular attention to the catalytic role played by stellar objects in the transformation of ubiquitous chemical precursors, such as formamide, formaldehyde and hydrogen cyanide. Thus, amino acids, nucleobases, sugars, lipids and carboxylic acids emerge as very easily synthesizable molecules in the universe ready to join in the first living cell.