The asteroid credited with the extinction of the dinosaurs 66 million years ago is likely to have originated from the outer half of the solar system’s main asteroid belt, according to new research by Southwest Research Institute (SwRI). Space.com reports: Known as the Chicxulub impactor, this large object has an estimated width of 6 miles (9.6 kilometers) and produced a crater in Mexico’s Yucatan peninsula that spans 90 miles (145 kilometers). After its sudden contact with Earth, the asteroid wiped out not only the dinosaurs, but around 75 percent of the planet’s animal species. It is widely accepted that this explosive force created was responsible for the mass extinction that ended the Mesozoic era. Researchers used computer models to analyse how asteroids are pulled from their orbit in different areas of the asteroid belt and drawn towards planets. The observations of 130,000 model asteroids, along with data and behaviour seen in other known impactors, found that objects are 10 times more likely to reach Earth from the outer asteroid belt than previously thought.
Prior to crashing into Earth, the extinction-causing asteroid orbited the sun with others, in the main asteroid belt. This concentrated band lies between planets Mars and Jupiter, with its contents usually kept in place by the forces of gravity. Before this study was released, scientists thought that very few of Earth’s impactors escaped from the belt’s outer half. But, researchers at SwRI discovered that “escape hatches” could be created by thermal forces, which pull more distant asteroids out of orbit and in the direction of Earth. The objects found in these outermost parts of the asteroid belt include many carbonaceous chondrite impactors. These are dark, porous and carbon-containing rocks which can also be found on Earth. Leading up to this research, other scientists have attempted to learn more about the object that doomed the dinosaurs. This included examinations of 66-million-year-old rocks. By doing this, geologists discovered that the Chicxulub asteroid had a similar composition to today’s carbonaceous chondrites. By looking at wide timescales of the Chicxulub asteroid, the scientists could predict that a 6-mile asteroid is likely to come into contact with Earth once every 250 million years. Their model showed almost 50 percent of these significant impactors to be of the same carbonaceous chondrite composition. Details of the new study will be published in the November 2021 issue of the journal Icarus.
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