Over four and a half billion years ago, our solar system consisted of a disk of debris, which slowly coalesced into the sun, planets, moons, and asteroids that comprise our solar system.
Asteroids sometimes travel along a path that put them on a collision course with Earth. More often than not, they burn up when entering our atmosphere, but occasionally they’re large enough that a portion, or meteoroid, makes it through Earth’s atmosphere. Whatever survives the intensity of Earth’s atmosphere and makes it to the surface is called a meteorite.
Despite the infrequency and relatively benign impact of meteorites, planetary defense specialists believe we should be better at predicting when and where an impact might happen.
And that's where a new study comes in.
Mikael Granvik of Lulea University of Technology in Finland is lead author of a study aimed at better pinpointing the origins of asteroids.
"Laboratory studies of meteorites provide a wealth of information of small bits of the [asteroid belt] disk, but the knowledge is of limited use unless we understand the context, which is provided if we can link the meteorites to their source regions," Granvik said in an email to Seeker.
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The new study, published in the journal Icarus, plotted the orbits for space rocks that survived Earth's atmosphere and made it to the surface. Scientists compared the orbits to a model that told them where in the solar system that meteorite likely came from.
The research identified a few different origin stories. For example, a carbonaceous meteorite found in Tagish Lake in British Columbia likely came from the inner part of the asteroid belt, instead of the outer part.
Gravnik warned that his initial sample of about 24 events is too small to draw definitive conclusions, but the data suggests that so far, H chondrites (meteorites with a high iron abundance) come from the middle parts of the asteroid belt, while L chondrites (meteorites with lower iron abundance) come from the inner part. "For the other types of meteorites, we don't have enough data to say anything remotely certain," he said.
He added the scientists hope to refine their model with several new fireball events that happened while the paper was being written. "I want to see whether adding them will affect the big picture," he said.
Meanwhile, asteroid studies continue both in space and on Earth. Japan's Hayabusa2 spacecraft arrived at its destination asteroid, Ryugu, in late June. It is expected to touchdown on the asteroid and collect samples to return to Earth.