Chelyabinsk study confirms origin of dinosaur-killing asteroid
Sen—A meteor that broke up over Russia in February last year helped confirm a theory on where the asteroid that killed the dinosaurs 66 million years ago came from, according to a new study.
The 17-meter-wide asteroid broke up over the city of Chelyabinsk on Feb. 15, 2013, causing injuries in hundreds of people as glass shattered and debris flew below. The event caused a resurgence in asteroid-watching campaigns worldwide to track those interluders that could cause a threat to Earth.
Perhaps the most notorious example is the supposed 10-km wide asteroid that smashed into the Earth and killed the dinosaurs millions of years ago. For decades, astronomers believed the asteroid was linked to the breakup of a larger body that created the Baptistina Asteroid Family past the orbit of Mars. The breakup sent some bodies close to Earth, including the one that hit the planet, the theory went.
Artist's conception of a broken-up asteroid. Image credit: NASA/JPL-Caltech
The Chelyabinsk meteorite shows examples of "shock darkening" that happens when a larger asteroid catastrophically breaks up, a phenomenon first reported in the 1990s. Some of its material is also unshocked.
"Shock and impact melt can make bright asteroids dark," said Vishnu Reddy, a Planetary Science Institute Research Scientist who led the research. 'In other words, not all dark asteroids are rich in carbon as once thought."
Looking at Chelyabinsk, its spectrum appears to match those in the Baptistina Asteroid Family. But comparing that spectrum to a fossil meteorite that was presumably from the dinosaur impactor, a different picture emerges of the dinosaur impactor's origins.
The researchers concluded that Chelyabinsk may have come from the family, while the dinosaur impactor did not. This agrees with conclusions raised by a 2011 study by NASA's Wide-field Infrared Survey Explorer (WISE) mission, which studied the asteroid family from space.
The trail left by the Chelyabinsk super-bolide that exploded in the atmosphere over Russia a year ago. Image credit: Alex Alishevskikh. CC BY-SA 3.0
"The new finding has implications for hazards from Near-Earth Objects and for mining asteroids for space-based resources," Reddy added. "A potential target identified as primitive and rich in volatiles/organics and carbon based on its spectral colors could in fact be just shocked material with entirely different composition."
The research is available in the journal Icarus. Meanwhile, a recent separate study on Chelyabinsk tried to pinpoint the orbit of the "parent body" of the asteroid. While the planetary community is united in believing the Chelybainsk impactor was a smaller fragment from a larger Apollo-type asteroid, the paper states, the orbit of the meteor before it struck Earth is still being pinned down.
The statistical analysis, by brothers Carlos and Raúl de la Fuente Marcos, both professors studying orbital dynamics at the Complutense University of Madrid, concludes that the parent body was likely a part of the main asteroid belt.
Another meteorite of similar composition, called Paragould, appeared to have an orbit that was similar to that of asteroids 2007 BD7 and 2011 EO40, which are locked in orbital resonances in jupiter. But more testing will be needed, the researchers said.
"The dynamical relationship is certainly encouraging, but the current orbits of these asteroids are not reliable enough to claim a conclusive connection," read the paper, which is available on preprint publishing site Arxiv and subsequently published in the Monthly Notices of the Royal Astronomical Society.
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