Glycine was found, in particular, on the surface of the comet Churyumov-GerasimenkoComplex organic compounds are everywhere. They exist on our planet, on planetary and planet, and found them on the surface of comets and in interstellar space. But what is the process of their formation in space? Recently, scientists have clarified this by recreating the conditions of outer space. Specialists were able to obtain the amino acid glycine, sending a thin film of matter to the electron beam under ultrahigh vacuum and low temperatures.
According to a number of astronomers and planetologists, such conditions are characteristic of the formation of complex organic molecules in the interstellar medium, comets and ice satellites of the planets. The article in question was
published in The Journal of Chemical Physics, a short summary can be found
in the preprint here .
Glycine, which was discussed above, is one of the basic amino acids, which is part of the majority of known proteins. It was discovered on the
comet Churyumov-Gerasimenko by the efforts of the Rosetta interplanetary station, as well as practically in open space, in the interstellar medium. Moreover, in addition to glycine, more than one and a half dozen different organic compounds were found on comets, including alcohols, amines, nitriles, amides, and isocyanates.
It is believed that amino acids are formed in the ice shells of dust grains in molecular clouds or on the surface of ice, covering various objects, including comets, asteroids and smaller ones. The process is caused by the action of streams of high-energy particles and the radiation of stars.
A group of scientists led by Michael Wells decided to study the details of the process, including clarifying the role of non-thermal secondary electrons. According to researchers, these particles are crucial in the formation of organic compounds. To check his statement, it was decided to test the effect of particles on films with the inclusion of carbon dioxide, ammonia and methane. They were besieged on platinum foil under ultrahigh vacuum conditions at a very low temperature — only 22 Kelvin.
After deposition, the films were irradiated with high-energy particles (electrons) with energies up to 70 electron volts. And then the films were analyzed for the content of organic compounds, including glycine.
It turned out that the scientists' assumption was correct - glycine and other organic substances are actually formed. True, the frequency of formation of an amino acid molecule is not too high. Only one of the 260 high-energy electrons contributed to the appearance of glycine. Experts believe that on one square centimeter of the ice surface of a space object, up to 60 glycine molecules can be formed under appropriate conditions. If we take into account the very long lifetime of cosmic objects like comets, we can safely talk about the formation of a large amount of amino acid in some cases.
As for comets, organic molecules do not freeze into ice, as previously thought. In many cases, they are located on the surface of space objects in the form of granules of microscopic size. Proponents of panspermia can be satisfied - there is a far nonzero probability that comets contribute to the formation of the original “broth” in reservoirs suitable for maintaining the protein life of the planets. By the way, comets, according to some scientists, can bring with them a large amount of water to the planets.
The discovery of an amino acid on the comet Churyumov-Gerasimenko is not out of the ordinary. Back in 2009, the Stardust probe penetrated the tail of Comet Wild 2, collecting material samples there. And in these samples glycine was also found.
Experiments of terrestrial scientists show that complex organic compounds, including amino acids, can be formed almost throughout the Universe. The conditions have already been called - you need the presence of ice and hard cosmic radiation.