Meteorite discovered in Antarctica offers scientists peek at solar system, mystery of life

Researchers at NASA’s Goddard Space Flight Center found that an abundance of amino acids was locked up inside an ancient meteorite discovered in Antarctica in 2012 that may give scientists a sneak peek into the secrets of the solar system and life.

The golf ball-sized meteorite named Asuka 12236 was discovered by a team of Japanese and Belgian researchers after they picked up a small rock that appeared coal-black against snow-white Antarctica during a 2012 expedition there. 

As it turns out, Asuka 12236 is one of the best-preserved meteorites of its kind ever discovered. And now, NASA scientists have shown that it contains microscopic clues that could help them solve a universal mystery: How did the building blocks of life flourish on Earth?

These primordial molecules included aspartic and glutamic acids, which are among the 20 amino acids that form themselves into countless arrangements, making up millions of proteins. Proteins then go on to power the chemical gears of life on Earth, including essential bodily functions in animals.

Led by Goddard astrobiologist Daniel P. Glavin, the team also found that Asuka 12236 had more left-handed versions of some amino acids. There’s a right-handed and left-handed mirror-image version of each amino acid, like your hands are mirror images of each other. All known life uses only left-handed amino acids to build proteins. Increasingly, Glavin and his colleagues are finding that meteorites are chock-full of these left-handed chemical precursors to life.

“The meteorites are telling us that there was an inherent bias toward left-handed amino acids before life even started,” Glavin said. “The big mystery is why?”

Differences in the types and amounts of amino acids preserved in such rocks allow scientists to build a record of how these molecules evolved through time and circumstances, including exposure to water and heat inside their parent asteroids.

^{NASA Goddard astrobiologist Daniel Glavin poses in 2002 next to a meteorite he had just found during an expedition in Antarctica. Credits: Antarctic Search for Meteorites/Daniel Glavin}

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Discover mysteries of the universe

On the timeline of the solar system, Asuka 12236 fits in toward the very beginning – in fact, some scientists think that tiny pieces of the meteorite predate the solar system. These are among the most interesting rocks to study for scientists who focus on the origin of life since many contain a highly complex mixture of organic compounds associated with living things.

“It's fun to think about how these things fall to Earth and happen to be full of all this different information about how the solar system formed, what it formed from, and how the elements built up in the galaxy,” said Conel M. O'D. Alexander, a scientist at the Carnegie Institution for Science in Washington, D.C., who collaborated on the Asuka 12236 analysis.

Meteorites like Asuka 12236 are pieces of much larger asteroids. These fragments were flung into the solar system during asteroid collisions more than 4.5 billion years ago and ultimately made their way to Earth’s surface after surviving a fiery descent through our atmosphere. For Alexander and Glavin, these rocks are like history books that fall from the sky and deliver chemical information about the early solar system. Space rocks are the only source of this information because erosion and plate tectonics on Earth have wiped away the chemical history of our planet.

With Asuka 12236, scientists are getting a peek at the very first amino acids produced in the solar system and the conditions that led to the variety and complexity of these molecules.

“Understanding the kinds of molecules, and their handedness, that were present in the earliest days of the solar system puts us closer to knowing how the planets and life formed,” said Jason P. Dworkin, a Goddard astrobiologist.

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