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'Dark Chemistry' Can Help in Building Blocks of Life Without Stars' Radiation, Says Study

Glycine was recently discovered on a meteorite that is very far away in the Kuiper belt and away from sun's radiation. (Image for representation.)

Glycine was recently discovered on a meteorite that is very far away in the Kuiper belt and away from sun's radiation. (Image for representation.)

The simplest amino acid known as Glycine has always been believed to be star-radiation-dependant in its creation. However, a new study shows it can even form in a process of “dark chemistry”.

Molecules of life need water and sunlight to form, or so is the popular notion and scientific understanding. However, there is one prebiotic molecule, which is a building block of life, that can be born even after the epic darkness of harsh space, even away from every known source of light i.e. stars.

The simplest amino acid known as Glycine has always been believed to be star-radiation-dependant in its creation. However, a new study shows it can even form in a process of “dark chemistry” i.e. a chemical process taking place entirely without light energy.

This year, glycine discoveries have led to some stellar hypotheses by space scientists. It was recently discovered on a meteorite as well as the surface of Venus; sparking up debate about possible life in the distant Venusian past. While Venus discovery is special, what’s more interesting is glycine presence on Comet 67P/Churyumov-Gerasimenko, which is originally from the Kuiper belt and quite far from the sun’s irradiation.

It was suggested that glycine can even form in high or absent irradiation. Like, when interstellar ice is bathed in radiation – ultraviolet, cosmic, thermal, X-ray – in the later stages of star formation. However, high energies can destroy amino acids.

The researchers then simulated conditions of dark interstellar space, without clouds of dust and thin layers of ice. They attacked the atoms with precursors to the desired amino, particularly, methylamine, an amine precursor to glycine. One of the authors of the study clarified that glycine in its compound form has not been discovered in interstellar space. However, methylamine has been found and there is data to show that methylamine can form in space without light energy.

The team led by astro-chemist Sergio Ioppolo analysed methylamine-enriched ice to see if glycine will follow methylamine mechanism and form without irradiation. A system known as SURFRESIDE2 is used to investigate surface reactions in interstellar space. It was cooled to replicate a cold interstellar temperature of 13 Kelvin (-260 degrees Celsius, or -436 degrees Fahrenheit), where ice could form. The gas was then inserted into the system.

The result was published in the journal Nature Astronomy. They discovered that glycine could form within these conditions and that ice was essential to the process. Additionally, astrochemical modelling was used to validate these results. This again suggested similar results that given enough time, glycine would form in interstellar space in small quantities.

However, in the cold vacuum of space, they cannot develop much. The research shows that glycine and methylamine form before planetary formation begins, suggesting the seed of life comes before the planet. It also suggests there might be other prebiotic molecules trapped in layers of ice on various meteorites, comets, planetesimals and ultimately planets.


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