Ancient Meteorites That Crashed to Earth Carried Ingredients for Life, Including Water and Organic Compounds

A halite crystal found in a meteorite, which measures less than a millimeter across. Queenie Chan/The Open University, UK

Updated | Tiny salt crystals encased in rock that fell to Earth from ancient alien worlds contain organic compounds and water vital to life, finds a new analysis that suggests how space rocks plummeting to Earth could have seeded life.

"Everything leads to the conclusion that the origin of life is really possible elsewhere," co-author Queenie Chan, a planetary scientist at Open University in the U.K., said in a press release. "There is a great range of organic compounds within these meteorites, including a very primitive type of organics that likely represent the early solar system's organic composition."

The paper, published in the journal Science Advances, scrutinized the "early solar system fluids" trapped within two space rocks' salt crystals. "It's like a fly in amber," David Kilcoyne, a scientist at Berkeley Lab's Advanced Light Source, a Department of Energy facility that took part in the research, said in a press release.

The two meteorites the scientists analyzed, which were both discovered in 1998, are called Zag and Monahans. They date from 4.5 billion years ago, around the earliest days of our solar system. The scientists think the meteorites originated from asteroids like Ceres, the largest object in the asteroid belt and considered potentially habitable, and Hebe, another relatively large asteroid, which might be close enough to exchange materials the way subway riders exchange germs.

And in fact, the team behind the new paper saw signs that Zag and Monahans or the asteroids they sprang from had crossed paths somehow long before they fell to Earth. "Things are not as simple as we thought they were," Chan said.

The scientists got their hands on a pristine piece of the Zag meteorite, then went about destroying it—exceptionally carefully, of course. First, they took the samples to a high-powered clean room to make sure they didn't contaminate it. Then, they carefully cracked them open using tools that had been roasted at over 900 degrees Fahrenheit for a full 24 hours, to further reduce contamination risk. Finally, they analyzed the amino acids—building blocks of proteins—they found inside.

Read more: Mysterious Ancient Egyptian Rock Made of Tiny Diamonds Formed Before the Solar System Existed

Similarly, they took a tiny crystal from within the Monahans meteorite and dissolved it away, like dropping salt in a pot of super-clean boiling water. Analyzing what remained told them the pocket had contained carbon, nitrogen and oxygen—three critically important elements to life as we know it.

Piecing together all the clues they gathered, the scientists think that the salt crystals themselves formed as crusts on the surface of an asteroid like Ceres. Then a large eruption shot the crystals in a stream of water or ice out into space, where they picked up their striking blue color. Eventually, they landed on a second asteroid, where they were buried by other rock—until that asteroid too shed them in the form of the meteorites that carried them to Earth.

Confirming that these compounds that are so important to life as we know it can fall to Earth in this way isn't proof that they triggered the beginnings of life, but it does mean that scenario is a real possibility.

This story has been updated to include a second comment from Queenie Chan.