Life's building blocks can form in interstellar clouds without stellar fusion

Scientists previously detected the presence of the amino acid glycine in the coma of the comet 67P/Churyumov-Gerasimenko. Photo by ESA
Scientists previously detected the presence of the amino acid glycine in the coma of the comet 67P/Churyumov-Gerasimenko. Photo by ESA

Nov. 16 (UPI) -- New research suggests one of life's most important building blocks, a simple amino acid called glycine, can form inside interstellar clouds well before the emergence of stars and planets.

Scientists have previously detected glycine in the coma of the comet 67P/Churyumov-Gerasimenko. Stardust sampling missions have also turned up evidence of interplanetary glycine.


Until now, scientists thought significant amounts of energy were required for the formation of glycine and other amino acids -- the kind of energy produced by stars.

However, new experiments -- detailed Monday in the journal Nature Astronomy -- suggest "dark chemistry" reactions can produce glycine on the surface of icy dust grains without the assistance of stellar energy.

"Dark chemistry refers to chemistry without the need of energetic radiation," lead study author Sergio Ioppolo said in a news release.

"In the laboratory we were able to simulate the conditions in dark interstellar clouds where cold dust particles are covered by thin layers of ice and subsequently processed by impacting atoms causing precursor species to fragment and reactive intermediates to recombine," said Ioppolo, a researcher at Queen Mary University of London.


The experiments first revealed the formation of methylamine, a glycine precursor. After repeated tests and the assistance of precise, atomic beam-powered diagnostic technologies, researchers were able to also detect the production of glycine.

The analysis showed that while solar energy was nonessential, water ice was vital to the glycine formation process. Researchers were able to confirm their experimental results using astrochemical models.

"From this we find that low but substantial amounts of glycine can be formed in space with time," said study co-author Herma Cuppen, professor at Radboud University in the Netherlands.

Based on the results of the dark chemistry experiments, researchers hypothesize that glycine can exist in abundance prior to the formation of stars and planets -- preserved in the icy particles of interstellar clouds and easily incorporated into comets.

"Once formed, glycine can also become a precursor to other complex organic molecules," said Ioppolo. "Following the same mechanism, in principle, other functional groups can be added to the glycine backbone, resulting in the formation of other amino acids, such as alanine and serine in dark clouds in space."

"In the end, this enriched organic molecular inventory is included in celestial bodies, like comets, and delivered to young planets, as happened to our Earth and many other planets," Ioppolo said.


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