On September 28, 1969, an extraordinary event shook the tranquility of the small town of Murchison, Australia. At 10:58 in the morning, local time, a meteorite crashed near the town, scattering fragments over an area of approximately 13 square kilometers.

Scientists quickly mobilized to collect over 100 kg of scattered fragments, the largest being about 7 kg. Prompt collection was crucial to prevent contamination of the specimens with terrestrial compounds.

Moreover, the meteorite’s fall occurred just two months after the historic Apollo 11 moon landing, meaning that laboratories already had the necessary equipment to analyze extraterrestrial materials.

Studies conducted by Keith Kvenvolden’s team at NASA’s Ames Research Center revealed that the Murchison Meteorite was no ordinary meteorite. Classified as a carbonaceous chondrite of the CM2 group, this meteorite contained a significant amount of carbon, mainly in the form of organic compounds.

But what truly astonished researchers was the presence of 18 amino acids, the basic units of proteins and fundamental building blocks of life as we know it.

Subsequent analyses confirmed that these amino acids had formed abiotically, meaning without the intervention of living organisms. Furthermore, it was discovered that some of them, such as alanine and isovaline, had the same configuration as the amino acids found in terrestrial proteins.

But amino acids were not the only organic compounds of interest found in the meteorite. Purines and pyrimidines, the basic components of DNA and RNA, the molecules carrying genetic information in all known living beings, were also detected.

These discoveries have led scientists to hypothesize that the organic compounds necessary for the emergence of life on Earth could have arrived from outer space, transported by meteorites like Murchison.

In fact, it is estimated that during a period of intense bombardment lasting 200 million years, the amount of organic matter reaching Earth was 25,000 times greater than the current amount of biologically recycled carbon on the surface of our planet.

But perhaps the most surprising discovery related to the Murchison Meteorite came in early 2020 when presolar silicon carbide grains extracted from the meteorite were dated.

These tiny grains turned out to be stardust with an age of 7.000 billion years, making them the oldest material found on Earth. Their isotopic composition suggests they originate from a type II supernova, generated by a star with a mass approximately 25 times that of the Sun.

The Murchison Meteorite has provided us with a unique window into the origins of life and the evolution of the universe. Its organic compounds and presolar grains are witnesses to cosmic processes that took place long before the formation of our solar system.


This article was first published on our Spanish Edition on March 11, 2024. Puedes leer la versión en español en El Meteorito Murchison contiene el material más antiguo encontrado hasta ahora en la Tierra

Sources

Murchison (The Meteoritical Society) | Uwe J. Meierhenrich, Guillermo M. Muñoz Caro, et al., Identification of diamino acids in the Murchison meteorite. PNAS June 11, 2004, 101 (25) 9182-9186, doi.org/10.1073/pnas.0403043101 | Engel, M., Nagy, B. Distribution and enantiomeric composition of amino acids in the Murchison meteorite. Nature 296, 837–840 (1982). doi.org/10.1038/296837a0 | Wikipedia


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