In October 2020, a minor spacecraft shortly touched down on an asteroid to grab a piece of it to take it to Earth. Nearly two years later, scientists have realized that if the OSIRIS-REx spacecraft had lengthened its stay for even a tiny bit longer, it would have plummeted right into the asteroid.
That’s because the asteroid Bennu is nothing like the scientists had thought. Instead of being solid, flying rock, Bennu is entirely made up of tiny, pebble-like particles that are not properly bound together, thereby leaving lots of space on its surface. “It’s somewhat similar to a plastic ball pit,” NASA explains in a news release. “Our expectations about the asteroid’s surface were completely wrong,” Dante Lauretta, principal investigator of OSIRIS-REx and lead author of the latest paper listing the findings, announced during the release.
OSIRIS-REx reached the asteroid in December 2018 with the purpose of retrieving a sample from Bennu and bringing it to Earth for research. The spacecraft landed on Bennu in October 2020, expanding its robotic arm to scoop up a chunk of the asteroid. OSIRIS-REx then instantly fired up its thrusters to retreat from Bennu. The spacecraft’s sampling head came in contact with Bennu’s surface for roughly 6 seconds before retreating. By bothering some of the dust and pebbles on the asteroid, OSIRIS-REx successfully grabbed a couple of ounces of material.
The short rendezvous created quite an impression on Bennu, resulting in a violent explosion of pebbles and a hole that was about 26 feet wide.