Asteroid Bennu Has Been in Earth's Vicinity for 1.75 Million Years, Reveals New Study
In this image taken from video released by NASA, regolith is dispersed as the Osiris-Rex spacecraft attempts to take a sample of the surface of asteroid Bennu on Tuesday, Oct. 20, 2020. (NASA via AP)
Asteroid Bennu has been in the news for the past few weeks for NASA’s historic sample collection mission on the space rock. Now, scientists have found that Bennu’s relation with Earth is a lot older than the space agency’s haul.
Research has revealed that the asteroid has been in an orbit that brings it astronomically close to our home planet for 1.75 million years. The OSIRIS-REx spacecraft sent by NASA to collect samples from the asteroid has proved to be a boon as images and data from Bennu are continuously surprising scientists. The latest study is also based upon the images sent out by OSIRIS-REx’s camera setup.
Bennu was once part of a larger asteroid body located in the main asteroid belt in between the orbits of Mars and Jupiter. An impact resulted in the breaking of the parent body and resulted in the formation of Bennu as an independent asteroid. The incident provided Bennu with the momentum to enter an orbit closer to Earth. But scientists were not sure as to when this happened.
By studying the pictures of the craters on the surface of Bennu, experts calculated whether the impacts that had caused the craters happened in the solar system or not. “An asteroid's history is determined in large part by its strength against collisions with other objects,” said the authors.
If the craters were large (about 16 feet across), they were most likely caused in the asteroid belt. So scientists went for the craters that were less than 19.6 inches to determine Bennu’s timeline of entry into near-Earth space.
This calculation revealed that Bennu entered a near-Earth orbit some 1.75 million years ago. This has led to the rock coming really close to our world which makes scientific studies on Bennu so much easier. At present, it's about 200 million miles away from Earth.
The study has been published in the journal Nature on 26 October.