The asteroid that wiped out the dinosaurs came from an unexpected place | technology

The asteroid that killed him dinosaurs It likely came from the outer half of the main asteroid belt, a region believed to produce few collisions.

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Researchers from the Southwest Research Institute (SwRI) have shown that processes that send large asteroids to Earth from that region occur at least 10 times more often than previously thought and that The composition of these bodies matches what we know about the probe that killed the dinosaurs. They publish the results in Icarus.

The team combined computer models of asteroid evolution with known asteroid observations to investigate the frequency of so-called Chicxulub events. More than 66 million years ago, an object estimated to be 9 kilometers in diameter collided in what is now Mexico’s Yucatan Peninsula and formed the Chicxulub crater, which is more than 130 kilometers in diameter. This massive explosion caused a mass extinction Which ended the era of the dinosaurs. Over the past few decades, much has been learned about the Chicxulub event, but each progress has raised new questions.

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Two important questions remain unanswered: “What is the source of the collider?” and “How many times have these impact events occurred on Earth in the past?”Co-author William Bottke explains in a statement.

To explore the Chicxulub effect, geologists previously examined 66 million-year-old rock samples found on Earth and within the drill core. The results indicate that the probe was similar to the carbonaceous chondrite class of meteorites.Some of the most pristine materials in the solar system. Interestingly, while carbonaceous chondrites are common among many mile-wide objects approaching Earth, today there are nowhere near the sizes needed to produce a Chicxulub effect with any reasonable probability.

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“We decided to find where the Chicxulub brothers might be hiding.”said David Nesvorny, lead author of a paper describing the research.

To explain its absence, several previous groups have simulated large ruptures of asteroids and comets in the inner solar system, observing waves of collisions on Earth and the largest of which produce the Chicxulub crater.Potky said. “While many of these models have interesting properties, none have provided a satisfactory match with what we know about asteroids and comets. Looks like we’re still missing something important.”.

To solve this problem, the team used computer models that track how objects escape from the main asteroid belt, a region of small objects located between the orbits of Mars and Jupiter. Over eons, thermal forces allow these bodies to drift toward dynamics “escape hatches” Gravitational “kicks” can push the planets into orbits close to Earth.

Using NASA’s Pleaides supercomputer, the team followed 130,000 models of asteroids that evolved in this slow and steady way over hundreds of millions of years. Particular attention has been paid to asteroids located in the outer half of the asteroid beltIt is the farthest part of the sun. To their surprise, they found that asteroids 9 km wide from this region hit Earth at least 10 times more often than previously expected.

every 250 million years

“This finding is interesting not only because the outer half of the asteroid belt is home to a large number of carbonaceous chondrites, but also because the team’s simulations can, for the first time, reproduce the orbits of large asteroids about to approach Earth,” co-author Simon Marchi said. “Our explanation of a shocking source Chicxulub fits perfectly with what We already know how asteroids evolve.”

Overall, the team found that 9 km-wide asteroids strike Earth once every 250 million years on average, a timescale that gives reasonable odds that the Chicxulub crater occurred 66 million years ago. In addition, nearly half of the impacts were carbonaceous chondrites, which is a good match with what is known about the Chicxulub Collider.

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