Amino acid formation from simulated mildly-reducing primitive Earth atmospheres by various energy sources

Abstract

It has been reported that amino acids can be formed easily from strongly-reducing atmosphere by various energy sources such as spark discharges since 1950s. Primitive Earth atmosphere is, however, assumed to have been only mildly-reducing. We examined possible formation of amino acids from a mixture of CO₂, CH₄, N₂ and H₂O of various mixing ratios by spark discharges, proton irradiation, or UV irradiation. If partial pressure of CH₄ was 10% or less, amino acids were not formed by spark discharges, but amino acids could be formed by proton irradiation even if the partial pressure of CH₄ was as low as 0.5%. It was difficult to form amino acids from mildly-reducing gas atmospheres by solar UV only, but the solar UV flux was much larger than other possible energy sources on the primitive Earth. We are planning to examine possible formation of amino acids by synergy of solar UV and other energy sources like cosmic rays.