Stability of nucleobases in small solar system bodies.

Abstract

A variety of organic compounds have been detected, which suggests extraterrestrial organic compounds contributed to generation of life on the Earth. It was reported that nucleobases were formed in experiments simulating interstellar environments. The presence of nucleobases in meteorites suggested that the organic compounds produced in molecular clouds was once incorporated into small bodies in early solar system, which were then delivered to Earth by meteorites. In the present study, to understand the stability of nucleobases in small bodies in early solar system, nucleobases were dissolved in an aqueous solution of ammonia and/or formaldehyde, were sealed in glass tubes, and were irradiated with gamma-ray from ⁶⁰Co source. Their recoveries were analyzed by reversed-phase HPLC. There were differences in stability among the different types of nucleobases: Purine bases remaining more than pyrimidine bases. The solid state should also be examined, as the liquid was probably almost gone before the decay of ²⁶Al was almost complete in the actual small-body environment.