  Impacts by small solar system bodies (meteoroids, asteroids, comets and
transitional objects) are characterized by a combination of energy dynamics and
chemical modification on both terrestrial and small solar system bodies. In
this context, the discovery of glycine amino acid in meteorites and comets has
led to a hypothesis that impacts by astronomical bodies could contribute to
delivery and polymerization of amino acids in the early Earth to generate
proteins as essential molecules for life. Besides the possibility of abiotic
polymerization of glycine, its decomposition by impacts could generate reactive
groups to form other essential organic biomolecules. In this study, the
high-pressure torsion (HPT) method, as a new platform for simulation of impacts
by small solar system bodies, was applied to glycine. In comparison with
high-pressure shock experiments, the HPT method simultaneously introduces high
pressure and deformation strain. It was found that glycine was not polymerized
in the experimental condition assayed, but partially decomposed to ethanol
under pressures of 1 and 6 GPa and shear strains of <120 m/m. The detection of
ethanol implies the inherent availability of remaining nitrogen-containing
groups, which can incorporate to the formation of other organic molecules at
the impact site. In addition, this finding highlights a possibility of the
origin of ethanol previously detected in comets.
