How and when prebiotic organic material such as amino acids appeared on the primitive planet has been debated without resolution in the open literature for over 60 years. The possibility exists that both prebiotic raw materials and the requisite energy for their synthesis may have been delivered to the Earth simultaneously by a comet impact. The flux of organic matter to Earth via comets and asteroids during periods of heavy bombardment may have been as high as 1013 kg/yr, delivering up to several orders of magnitude greater mass of organics than what likely pre-existed on the planet.To this end, we have conducted quantum molecular dynamics simulations to close to equilibrium of the chemical reactivity within impacts of both oxygen-rich and oxygen-poor icy materials to peak conditions of up to 80 GPa and 5000 K. Upon expanding and cooling the oxygen-rich mixture, we observe the formation of functionalized aromatic hydrocarbons, as well as non-protein forming amino acids and a number of precursors to amino acids themselves, including formaldehyde, methane, and longer chain alkanes. In contrast, in the oxygen-poor mixture we observe a somewhat greater degree of complexity, including C-N heterocycles resembling polypeptides and a number of nitrogen containing long-chain alkanes. Our results indicate that impacts from cometary ices could have yielded a wide variety of prebiotic organic material including to amino acids on early Earth, independent of external features such as the presence of a catalyst, illuminating UV radiation, or pre-existing conditions on a planet. Knowledge of the chemical properties of the types of prebiotic molecules under extreme thermodynamic conditions is needed for a complete understanding of the role of impacting icy materials in the formation of life-building compounds.

Shock-synthesis of prebiotic compounds in oxidizing and reduced impacting simple ices

248th National Meeting (2014)

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