NASA solves a strange mystery hidden inside asteroid Bennu’s boulders
NASA's OSIRIS-REx mission discovered that the asteroid Bennu is covered in porous, crack-filled boulders rather than solid rock. This porosity explains why the asteroid cools down rapidly despite its rugged, boulder-strewn surface.
Why it matters
Understanding the physical properties of asteroids is essential for planetary defense and future sample return missions.
NASA's OSIRIS-REx mission encountered an unexpected mystery when it arrived at asteroid Bennu in 2018. Instead of the relatively smooth terrain that earlier observations had suggested, the spacecraft found a rugged landscape dominated by enormous boulders, with very few areas suitable for collecting samples.
"When OSIRIS-REx got to Bennu in 2018, we were surprised by what we saw," said Andrew Ryan, a scientist at the University of Arizona's Lunar and Planetary Laboratory, who led the mission's working group responsible for analyzing the physical and thermal properties of its samples. "We expected some boulders, but we anticipated at least some large regions with smoother, finer regolith that would be easy to collect. Instead, it looked like it was all boulders, and we were scratching our heads for a while."
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