The detection of the amino acid glycine and its amine precursor methylamine on the comet 67P/Churyumov-Gerasimenko by the Rosetta mission provides strong evidence for a cosmic origin of amino acids on Earth. How and when such molecules form along the process of star formation remains debated. Here we report the laboratory detection of glycine formed in the solid phase through atom and radical–radical addition surface reactions under dark interstellar cloud conditions. Our experiments, supported by astrochemical models, suggest that glycine forms without the need for ‘energetic’ irradiation (such as ultraviolet photons and cosmic rays) in interstellar water-rich ices, where it remains preserved, during a much earlier star-formation stage than previously assumed. We also confirm that solid methylamine is an important side-reaction product. A prestellar formation of glycine on ice grains provides the basis for a complex and ubiquitous prebiotic chemistry in space enriching the chemical content of planet-forming material.

通过Rosetta任务在彗星67P / Churyumov-Gerasimenko上检测到氨基酸甘氨酸及其胺前体甲胺，为地球上氨基酸的宇宙起源提供了有力的证据。这种分子如何以及何时沿着恒星形成过程形成仍然有争议。在这里，我们报告了在暗星际云条件下通过原子和自由基-自由基加成表面反应在固相中形成的甘氨酸的实验室检测结果。我们的实验得到了天化学模型的支持，表明在星际富水冰中甘氨酸的形成不需要“高能”辐射（例如紫外线光子和宇宙射线），而在星际富水冰中甘氨酸仍被保存下来，形成的时间比恒星形成的时间要早​​得多。先前假设。我们还证实，固体甲胺是一种重要的副反应产物。