Highly Porous Rocks Responsible for Bennu’s Surprisingly Craggy Surface

During fall 2019, NASA’s OSIRIS-REx spacecraft captured this image, which shows one of asteroid Bennu’s boulders with a bright vein that appears to be made of carbonate. The image within the circle (lower right) shows a focused view of the vein. (Credits: NASA/Goddard/University of Arizona)

TUCSON, Ariz. (University of Arizona PR) — Scientists thought asteroid Bennu’s surface would be like a sandy beach, abundant in fine sand and pebbles, which would have been perfect for collecting samples. Past telescope observations from Earth’s orbit had suggested the presence of ­­large swaths of fine-grain material called fine regolith that’s smaller than a few centimeters.