New Clues from Chondrites Reveal the History of the Solar System

Scientists have found evidence in meteorites that may hint at the discovery of a previously unknown region within the protoplanetary disk, a swirling disk of dust and gas that gave rise to the planets in our solar system.

The researchers studied meteorites called chondrites, which are thought to be the most primitive leftovers from the birth and infancy of the solar system about 4.6 billion years ago. Their names comes from their main component, called chondrules, which formed as molten droplets floating in space. Chondrites actually represent the earliest building blocks of rocky planets, such as Mars, Earth or Venus.

"Generally, chondrules are made up of minerals rich in silicon, but the chondrules we found in this meteorite are completely different in that they are composed of sulfide minerals," said Kelly Miller, one of the researchers, in a news release. "This suggests that they formed in a region that was rich in sulfur, and provides evidence for a previously unknown type of environment in the early solar system. Our discovery of the sulfide chondrules will help us put a quantifiable number on how much sulfide was enhanced in that region of the protoplanetary disk."

In this case, the researchers studied sections of R chondrites, a rare type of meteorite. One specimen was found in Antarctica, which is where they discovered a new type of building block, called sulfide chondrules.

The new sample has not been heated to high temperatures; this means that it hasn't been altered in its composition. It's a fragment of a larger asteroid, and some of that asteroid heated to higher temperatures, erasing the signature of the original building blocks of the asteroid. However, the new piece retains the original building blocks.

"These sulfide chondrules help us pin down when and where that sulfur enhancement occurred and help us better understand the process," said Miller.

The findings were presented at the 46^th Lunar and Planetary Science Conference.

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