Scientists have suggested that the residence time of asteroid Bennu in the inner solar system is 1.75 million years. The research results are published by the journal Nature.
Last year, NASA took a sample from the surface of the asteroid Bennu. It is a relatively small near-Earth asteroid (500 meters in diameter), part of the Apollo group, which was discovered as part of the LINEAR asteroid search project at the Socorro Observatory. On April 25, 2013, it was named after the Bennu bird, the symbol of the resurrection of Osiris.
Using orbital data from the OSIRIS-REx spacecraft, the researchers measured tiny craters (ranging from a few centimeters to a meter) on boulders scattered across its uneven surface. The goal is to shed light on the age of the asteroid.
While the collected sample will have tremendous scientific value when it is returned to Earth in 2023, a key challenge for scientists during Bennu’s orbit was to understand the entire asteroid’s geology (to provide an important context for the sample itself). This gives an idea of all the processes that could affect the nature of the sample.
The data collected by OSIRIS-REx on Bennu allowed scientists to locate impact craters on its surface, as well as on the surface of their boulders. The study showed that the lifetime of an asteroid around Earth is 1.75 million years.
Bennu is a dark pile of debris held by gravity and believed to be the remnant of an asteroid from a collision with a larger main-belt object. Boulders are scattered across its heavily cracked surface, indicating that it has led a tumultuous life since liberation from its much larger parent asteroid millions or even billions of years ago. Scientists are using impact crater studies to determine the age of planetary surfaces.