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About 66 million years ago, a massive object crashed into Earth just off the Yucatán Peninsula, cataclysmically ending the 150 million year reign of the dinosaurs. Today, scientists believe they have finally found its source.
The object was about six miles wide (just under 10 km), which has sparked much debate about the nature of the impactor, as 10 km is considered very large for an asteroid impactor but relatively small. for a comet. New research published in the journal Icarus suggests that an appropriately named dark primitive giant asteroid (GDP) was the culprit in the murder of the T-rex and his relatives.
Since the discovery of the Chicxulub impact crater in the Gulf of Mexico dispelled almost all doubts about what killed the non-avian dinosaurs, questions about the nature of the impactor have been hotly contested.
“Two critical questions still unanswered are: ‘What was the source of the impactor? And “How often have such impact events occurred on Earth in the past? Said Dr William Bottke, a research fellow at the Southwest Research Institute (SwRI) and co-author of the new research.
To answer this question, SwRI researchers looked at extant rock samples dating back 66 million years from the Chicxulub crater, both from rock layers on the ground and from drill core samples, which have identified the impactor as belonging to the class of carbonaceous asteroid chondrites. This only complicates matters, as very few carbonaceous chondrites over a mile wide have struck Earth, according to geological records.
Thus, the SwRI team set out to find a possible source of carbonaceous chondrites of sufficient size. “We decided to look for where the Chicxulub impactor siblings might be hiding,” said Dr David Nesvorný, lead author of the article.
Using computer modeling, the team now believe the asteroid originated in the outer half of the asteroid belt between Mars and Jupiter, a region long believed to produce few impactors. This region is filled with larger carbonaceous chondrite asteroids left over from the formation of the solar system billions of years ago.
Their model showed that the processes that can send these GDP asteroids back to Earth are 10 times more frequent than previously believed. And while not all of the displaced PIB asteroids end up hitting Earth, it does mean the inner solar system might have more heavy hitters flying around than we originally thought.
The modeling also puts the probability of such an impact every 250 million years, which is consistent with what scientists have found in the geological records.
“This result is intriguing not only because the outer half of the asteroid belt is home to a large number of carbonaceous chondrite impactors, but also because the team’s simulations can, for the first time, replicate the orbits of large asteroids about to approach Earth. Said Dr. Simone Marchi, co-author of the study. “Our explanation of the source of the Chicxulub impactor fits perfectly with what we already know about the evolution of asteroids.”
“This work will help us better understand the nature of Chicxulub’s impact,” Nesvorný said, “while also telling us where other large impactors of Earth’s deep past might come from.”
Fortunately, this also means that we might have some breathing space before a similar planet killer emerges from the darkest corners of the asteroid belt and also gives us an idea where to keep an eye out for the future.
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