Gamma Rays and Meteorites: The Unlikely Duo That May Have Sparked Life on Earth
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Loading... - Josue Lagos
- 23 Jan 2023
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Even as detailed images of distant galaxies from the James Webb Space Telescope show us more of the greater universe, scientists still disagree about how life began here on Earth. One hypothesis is that meteorites delivered amino acids — life’s building blocks — to our planet. Now, researchers reporting in the journal ACS Central Science have experimentally shown that amino acids could have formed in these early meteorites from reactions driven by gamma rays produced inside the space rocks.
Ever since Earth was a newly formed, sterile planet, meteorites have been hurtling through the atmosphere at high speeds toward its surface. If the initial space debris had included carbonaceous chondrites — a class of meteorite whose members contain significant amounts of water and small molecules, such as amino acids — then it could have contributed to the evolution of life on Earth. However, the source of amino acids in meteorites has been hard to pinpoint.
In previous lab experiments, Yoko Kebukawa and colleagues showed that reactions between simple molecules, such as ammonia and formaldehyde, can synthesize amino acids and other macromolecules, but liquid water and heat are required. Radioactive elements, such as aluminum-26 (26Al) — which is known to have existed in early carbonaceous chondrites — release gamma rays, a form of high-energy radiation, when they decay. This process could have provided the heat needed to make biomolecules. So, Kebukawa and a new team wanted to see whether radiation could have contributed to the formation of amino acids in early meteorites.
The researchers dissolved formaldehyde and ammonia in water, sealed the solution in glass tubes, and then irradiated the tubes with high-energy gamma rays produced from the decay of cobalt-60. They found that the production of ?-amino acids, such as alanine, glycine, ?-aminobutyric acid and glutamic acid, and ?-amino acids, such as ?-alanine and ?-aminoisobutyric acid, rose in the irradiated solutions as the total gamma-ray dose increased. Read More…
