For the first time, scientists are creating a geologic map of the asteroid belt—the region between Mars and Jupiter filled with rocky space objects.
By tracking the paths of falling meteorites, astronomers can now trace where many of these space rocks originally came from.
“This has been like solving a decade-long mystery,” said Peter Jenniskens, a meteor expert from the SETI Institute and NASA Ames Research Center.
“Every meteorite fall gave us a new clue, and now we’re starting to see the bigger picture.”
About ten years ago, Jenniskens and his team set up all-sky cameras in California and Nevada to capture the bright flashes of meteorites entering Earth’s atmosphere.
Other scientists and citizen observers around the world joined in, forming what is now called the Global Fireball Observatory.
Over time, they tracked 17 meteorite falls and gathered even more data from doorbell and dashboard cameras.
So far, 75 meteorites have had their paths recorded well enough to trace their origins. Most of these meteorites came from the asteroid belt, where over a million asteroids orbit the sun.
These smaller rocks are pieces of larger asteroids that broke apart in ancient collisions, forming debris fields or “families.”
One major finding is that a group of iron-rich meteorites, called H chondrites, likely came from the Koronis family in the main part of the asteroid belt.
These meteorites have orbits and exposure ages—how long they’ve been in space—that match different clusters within the Koronis family, such as the Karin, Koronis2, and Koronis3 clusters.
Another group of H chondrites seems to come from the Nele family, while a third group may be linked to the Massalia family in the inner asteroid belt.
Interestingly, asteroid (20) Massalia, the parent of this family, is also an H chondrite type.
Meteorites with less iron—called L and LL chondrites—mostly come from the inner asteroid belt. LL chondrites are connected to the Flora family, and scientists now believe L chondrites come from the Hertha family.
Asteroid Hertha itself looks dark and damaged, showing signs of a massive collision 468 million years ago that sent many L chondrites to Earth.
This research helps with planetary defense. If an asteroid is heading toward Earth, its orbit can tell us where it came from and what it’s made of—important information for protecting our planet.
There’s more to discover. As more meteorite falls are tracked and recovered, scientists hope to fill in the map even further.
“We’re just starting,” said Jenniskens. “It’s like we’ve drawn the first outlines of a new world.”
