In October 2020, NASA's OSIRIS-REx spacecraft approached the asteroid Bennu. The probe, which had been orbiting its target for nearly two years, lowered a robotic arm and scooped up about 4.4 pounds (2 kilograms) of dusty, rocky material from the asteroid's surface. This material is the first sample of an asteroid collected by a U.S. mission, and it might help scientists answer some puzzling questions: How old are asteroids like Bennu? And how long do they last?
To understand how long asteroids last, it's crucial to know when and how they formed. The asteroids in our solar system coalesced out of the protoplanetary disk, a thick collection of dust and rocky material that swirled around our sun 4.5 billion years ago.
