Earth might have derived building blocks for life from Meteorites and gamma rays

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Carbonaceous chondrites contain life’s essential building blocks, including amino acids, and their delivery of organic compounds would have played a key role in life’s emergence on Earth. Aqueous alteration of carbonaceous chondrites is an overall process induced by the heat produced by the radioactive decay of nuclides.

The emergence of life on Earth would have been aided if the early space debris had included carbonaceous chondrites, a type of meteorite that contains large amounts of water and tiny compounds like amino acids. However, it has been challenging to identify the source of amino acids in meteorites. 

Scientists have experimentally shown that amino acids could have formed in these early meteorites from reactions driven by gamma rays produced inside the space rocks.

Scientists have previously shown in earlier laboratory studies that interactions between simple molecules, such as ammonia and formaldehyde, can manufacture amino acids and other macromolecules, but this requires liquid water and heat.

Aluminum-26 (26Al), a radioactive element known to have been present in early carbonaceous chondrites, decays into gamma rays, a type of high-energy radiation. The heat required to create biomolecules might have been produced by this method. Scientists, therefore, sought to determine whether radiation may have played a role in the synthesis of amino acids in early meteorites.

Scientists 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 discovered that when the total gamma-ray dose increased, the formation of -amino acids, such as alanine and -aminobutyric acid, and -amino acids, such as -alanine and -aminoisobutyric acid, increased in the irradiated solutions.

The amount of alanine and -alanine present in the 1969 Australian meteorite known as the Murchison would have taken between 1,000 and 100,000 years to create, according to the researchers’ calculations based on these findings and the anticipated gamma ray dose from the breakdown of 26Al in meteorites.

Scientists noted, “This study provides evidence that gamma ray-catalyzed reactions can produce amino acids, possibly contributing to the origin of life on Earth.”

Journal Reference:

  1. Yoko Kebukawa*, Shinya Asano, Atsushi Tani, Isao Yoda, and Kensei Kobayashi. Gamma-Ray-Induced Amino Acid Formation in Aqueous Small Bodies in the Early Solar System. ACS Central Science. DOI: 10.1021/acscentsci.2c00588

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