60Co is a synthetic radioisotope produced in nuclear reactors. Not gamma rays from 26Al but from more readily available 60Co (cobalt-60). They combined compounds like formaldehyde and ammonia, both common chemicals in space, and exposed them to gamma rays. Kebukawa and her colleagues tested this idea in their laboratory. But the heat could’ve also driven the production of amino acids in meteors. Scientists think the heat from that decay is responsible for the melting and differentiation of some asteroids after they formed in the early Solar System. It was relatively abundant back when the Solar System was forming but has now decayed.Ģ6Al is unstable and releases gamma rays as it decays. It could’ve come from one of the two naturally-occurring isotopes of aluminum: 26Al.Ģ6Al is cosmogenic, meaning it was created when cosmic rays bombarded meteor fragments. We know carbonaceous chondrites contain water, but where did the heat come from? But only in the presence of liquid water and only when there’s heat to drive reactions. Lead author Kebukawa showed in previous research that reactions between simple molecules such as ammonia and formaldehyde could create macromolecules, including amino acids. Could they have delivered building blocks like amino acids to Earth, spurring on the appearance of life? Image Credit: University of Oxford There were more meteorites striking Earth billions of years ago. That’s the question behind the new study.Īrtist’s concept of a meteorite entering Earth’s atmosphere. There seems little doubt that carbonaceous chondrites contained amino acids back then and that they would’ve delivered them to the young Earth. That, along with their ancient age, makes them important because they hold clues to the early Solar System, back when Earth was settling down, and life was getting started. However, CCs contain something more important than carbon: they’re known for containing water and other molecules, including amino acids. Scientists thought they contained carbon because of their dark and grey appearance, but they actually contain less carbon than other meteorites. There are further classifications based on chemical compositions, isotopes, and mineralogy.Ĭarbonaceous chondrites (CCs) are a type of stony meteorite and are some of the most primitive. There are three top-level categories of meteorites: stony meteorites, iron meteorites, and stony-iron meteorites which are a combination of both types. Over time, scientists have classified meteorites into different families. When they do, people find some of them, and many have found their way to scientists’ labs. There are fewer of them now, though they still fall to Earth. Meteorites flew through space, slamming into things like particles in an accelerator. When Earth formed, the Solar System was a much more chaotic place. The lead author is Yoko Kebukawa, an associate professor in the Department of Chemistry at Yokohama National University. The study is “ Gamma-Ray-Induced Amino Acid Formation in Aqueous Small Bodies in the Early Solar System,” and it was published in ACS Central Science, the journal of the American Chemical Society. They’ve seen it in comets, interstellar dust clouds, and meteorites that fell to Earth, which led to the idea that meteorites contributed to the appearance of life on Earth.Ī new study shows that when meteorites are bathed in gamma rays, they produce more amino acids. Glycine is one of the simplest amino acids in the genetic code, and scientists have found glycine in objects in space. There are hundreds of amino acids, but only 22 appear in the genetic code. A new study fills in part of the picture by showing that meteorites bathed in gamma rays produce more amino acids.
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