2023-12-04 11:15:03
Although life on Earth is relatively new, from the point of view of geology, the elements that combined to form it could be much older than previously thought.
According to research carried out by the team of Joshua H. Marks, from the University of Hawaii at Manoa, Honolulu, United States, the simplest amino acid, carbamic acid, could have formed in interstellar ices close to stars or planets. The discovery could help better refine the search for prebiotic substances carried out by highly sensitive instruments such as the James Webb Space Telescope in distant regions of the universe where stars form.
It has long been hypothesized that amino acids, the building blocks of life, could have been formed during reactions in the “primordial soup” of the early prebiotic Earth.
However, another theory suggests that the amino acids could have been transported to the Earth’s surface by meteorites. These space rocks could have collected amino acids from dust or interstellar ice (water and other gases frozen by the low temperatures of outer space).
Marks and his colleagues investigated chemical reactions that might have taken place in interstellar ices that once existed near newly formed stars and planets.
Artistic recreation of a solar system in formation. (Illustration: NASA JPL)
The team created models of interstellar ices containing ammonia and carbon dioxide, and deposited them on a silver substrate that they slowly heated. Using Fourier transform infrared spectroscopy, they found that carbamic acid and ammonium carbamate began to form at 211 and 234 degrees Celsius, respectively. These low temperatures show that these substances, which can be converted into more complex amino acids, could have formed during the earliest, coldest stages of star formation.
The researchers also discovered that, at warmer temperatures, similar to those produced by a newly formed star, two carbamic acid molecules can join together to form a stable gas. The team hypothesized that these molecules could have been incorporated into the raw materials of solar systems, including our own, and reached the early Earth via comets or meteorites when the planet had already formed. The researchers hope that this work will inform future studies that use telescopes to search for unambiguous signals of prebiotic substances in the far reaches of the universe.
The study is titled “Thermal Synthesis of Carbamic Acid and Its Dimer in Interstellar Ices: A Reservoir of Interstellar Amino Acids.” And it has been published in the academic journal ACS Central Science. (Source: American Chemical Society)
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