GRAND FORKS — University of North Dakota researchers have been able to trace the origins of about 40% of the meteorites that fall to Earth.
The meteorites likely arose from a “cosmic crime scene” that took place in the distant past, in which an asteroid called “(6) Hebe” collided catastrophically with another asteroid, according to a new paper written by UND's Sherry Fieber-Beyer and Mike Gaffey.
Fieber-Beyer, an associate professor, and Gaffey, a professor, are a part of UND’s space studies department.
The collision shattered part of (6) Hebe, causing fragments of the asteroid to fly off into space. Some of the fragments collected in a cluster that has been orbiting the sun ever since. Some of the fragments occasionally exit the cluster and travel into the inner solar system, sometimes striking the Earth.
In their paper published in the Planetary Science Journal, Fieber-Beyer and Gaffey for the first time identify this asteroid family and link it to both (6) Hebe and the second most common type of meteorites that fall to Earth, UND said in a news release.
“We needed a family of small asteroids that shared the same chemical signature as Hebe, and so we have been on this quest to find them,” Fieber-Beyer said. “We collected data for several years and put together the paper that shows that, yes, there is such a family.”
About 40% of the meteorites that fall to Earth are made up of materials from the (6) Hebe asteroid.
The work isn’t new for Gaffey and Fieber-Beyer and the findings in the paper are more than 10 years in the making.
In 1998, Gaffey proposed that (6) Hebe could be the source of H-type ordinary chondrites. Around 75% of all stony meteorites found on Earth are ordinary chondrites — “ordinary” because they’re the most common group, and “chondrites,” a term that describes stony objects made up of some of the solar system’s oldest known rocks, UND’s release noted.
But since 1998, experts in the field have debated the likelihood of the link because of the lack of an associated family of asteroids, as well as the possibility for more than one source for these meteorites.
Fieber-Beyer began using telescopes in Hawaii to study a subset of small asteroids in 2008. The UND scientists found that the asteroids’ chemical signatures match with those H-type ordinary chondrite meteorites.
Then in 2010, Fieber-Beyer discovered other asteroids in a region near (6) Hebe with similar spectral signatures, but most of them were too far from (6) Hebe to conclusively suggest a link. Over the next decade, her team studied more asteroids that were closer to Hebe and found that they were part of the same asteroid family.
The findings culminated in the recently published paper.