What meteorites tell us about their birthplace in space

For years, scientists have puzzled over one big question: where do meteorites come from?

These rocky visitors crash into Earth from space, but tracing their paths back to specific locations in the asteroid belt has been a challenge.

Thanks to years of work tracking fireballs streaking across the sky, scientists are beginning to piece together the answer.

The new research comes from astronomers at Curtin University and the SETI Institute, in collaboration with NASA Ames Research Center.

The findings connect the orbits of 75 meteorites to their likely points of origin in the asteroid belt between Mars and Jupiter.

This long-term effort brings us closer to mapping the geology of our solar system’s asteroid neighborhood.

Catching fireballs on camera

About ten years ago, the team began setting up a network of all-sky cameras across California and Nevada.

These cameras were designed to catch the flash of light created when a meteorite hits Earth’s atmosphere.

“Others built similar networks spread around the globe, which together form the Global Fireball Observatory,” said astronomer Hadrien Devillepoix of Curtin University. “Over the years, we have tracked the path of 17 recovered meteorite falls.”

In addition to professional networks, many fireballs were also captured by doorbell cameras, dashcams, and videos from citizen scientists.

With enough data from these sources, the researchers could begin plotting the meteorites’ paths through space.

“Altogether, this quest has yielded 75 laboratory-classified meteorites with an impact orbit tracked by video and photographic cameras,” said study lead author Peter Jenniskens of the SETI Institute and NASA Ames Research Center.

“That proves to be enough to start seeing some patterns in the direction from which the meteorites approach Earth.”

Tracing meteorites to their source

Most meteorites that land on Earth come from the asteroid belt, home to over a million objects larger than one kilometer.

Many of these meteorites were originally part of larger parent bodies that broke apart in violent collisions. The resulting debris fields, or clusters, continue to spread out over time.

“We now see that 12 of the iron-rich ordinary chondrite meteorites (H chondrites) originated from a debris field called “Koronis,” which is located low in the pristine main belt,” said Jenniskens. “These meteorites arrived from low-inclined orbits with orbital periods consistent with this debris field.”

The researchers used a technique called cosmic-ray exposure dating to determine how long ago a meteorite was exposed to space. This method helps identify when the rock was dislodged from its parent body.

When matched with the dynamical age of the asteroid clusters, a clearer picture emerges.

“By measuring the cosmic ray exposure age of meteorites, we can determine that three of these twelve meteorites originated from the Karin cluster in Koronis, which has a dynamical age of 5.8 million years, and two came from the Koronis2 cluster, with a dynamical age of 10–15 million years,” said Jenniskens.

“One other meteorite may well measure the age of the Koronis3 cluster: about 83 million years.”

More families, more clues

Not all H chondrites came from Koronis. Some meteorites with steep orbits seem to be linked to the Nele asteroid family, located in the central belt.

Others, with an exposure age of about 35 million years, appear to come from the Massalia family in the inner belt.

“In our opinion, these H chondrites originated from the Massalia asteroid family low in the inner main belt because that family has a cluster of about that same dynamical age,” said Jenniskens. “The asteroid that created that cluster, asteroid (20) Massalia, is an H chondrite type parent body.”

The researchers also traced lower iron meteorites – L chondrites and LL chondrites – to their own source regions.

LL chondrites are strongly linked to the Flora family, while L chondrites likely originated from the Hertha family.

“We propose that the L chondrites originated from the Hertha asteroid family, located just above the Massalia family,” said Jenniskens.

“Asteroid Hertha doesn’t look anything like its debris. Hertha is covered by dark rocks that were shock-blackened, indicative of an unusually violent collision.”

“The L chondrites experienced a very violent origin 468 million years ago when these meteorites showered Earth in such numbers that they can be found in the geologic record.”

What this means for planetary defense

Understanding where meteorites come from is more than just a scientific curiosity. It’s also crucial for identifying and preparing for potentially hazardous asteroids that could threaten Earth.

“Near Earth Asteroids do not arrive on the same orbits as meteorites, because it takes longer for these to evolve to Earth,” said Jenniskens. “But they do come from some of the same asteroid families.”

This connection means that by learning which asteroid families are sending meteorites our way, scientists can better assess which larger bodies might pose a risk in the future.

Jenniskens and Devillepoix also examined other meteorite types and their possible source regions. While not every link is confirmed, the expanding map of meteorite origins is already providing key insights.

“We are proud about how far we have come, but there is a long way to go,” said Jenniskens. “Like the first cartographers who traced the outline of Australia, our map reveals a continent of discoveries still ahead when more meteorite falls are recorded.”

Next steps in meteorite tracking

In the future, scientists hope to observe more asteroids in space just before they reach Earth. That was the case in 2008, when a small asteroid named 2008 TC3 was tracked in space and then recovered after it landed.

Thanks to upcoming observatories and new detection technologies, researchers expect to repeat this process more often – and continue filling in the blanks on their asteroid belt map.

As more meteorites are tracked from sky to ground, each one becomes another puzzle piece in understanding our solar system’s past, and preparing for its future.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–