The essential molecule for life could originate from inorganic materials common in space

Image: Carbon dioxide and ethylene glycol have been detected in molecular clouds, for example in the star-forming region of the Orion Nebula. Image source: NASA, ESA, M. Roberto

Since the identification of glyceric acid in the Murchison and Murray meteorites more than two decades ago, the molecule has been the focus of astronomical, biological and astrochemical research in the laboratory. Glyceric acid is linked to the origin of life and is found in carbonaceous meteorites in quantities similar to amino acids. However, the method of its formation has remained unclear until now.

The study's authors were able to form glyceric acid and its isomer 2-hydroxyethyl hydrogen carbonate in a model of interstellar ice from carbon dioxide and ethylene glycol, after exposure to ionizing radiation at extremely low temperatures of up to 5 Kelvin. The reaction gains energy from the incident electrons.

Molecular clouds

Carbon dioxide and ethylene glycol are abundant in the interstellar medium and have been detected in molecular clouds, for example in the star-forming region of the Orion Nebula. Now that it has been shown that these materials can form glyceric acid, the presence of this sugar acid in interstellar environments is also plausible. The authors write that research could begin using telescopes, such as the Atacama Large Millimeter/submillimeter Array (ALMA).

Once glyceric acid and 2-hydroxyethyl hydrogen carbonate form in interstellar ice, they can be incorporated into asteroids, asteroids, and comets. Eventually, on early Earth-like planets, a small fraction of these molecules may serve as a source of biomolecules.

Detailed analyzes of the meteorites have shown that not only sugar-related organic compounds such as glyceric acid, but also amino acids and dipeptides may be included. Precise modeling studies are particularly important for understanding the origins of life, the study authors wrote. After all, reaction pathways in the laboratory show how prebiotic, biologically relevant molecules can form in space.