NASA Study Explains Bennu's Rapid Heating via Surface Cracks

NASA scientists have uncovered a key explanation for the unexpected thermal behavior of asteroid Bennu, revealing that networks of cracks within its boulder-like surface materials allow the rocky body to heat and cool more rapidly than previously thought. A new study, based on samples returned by NASA's OSIRIS-REx spacecraft, shows that these fractures, combined with porosity, reconcile discrepancies between remote observations and direct measurements. The findings, published on March 17, 2026, in Nature Communications, enhance understanding of asteroid structures and their evolution in the early solar system.

The OSIRIS-REx mission, launched in 2016, reached Bennu in December 2018 after a journey of billions of miles. Scientists anticipated finding large areas of fine, sandy regolith suitable for easy sample collection, based on Earth-based telescopic observations. Instead, the spacecraft's images revealed a rugged landscape dominated by large boulders, spanning a surface about a half-kilometer wide. This "rubble pile" asteroid, formed from fragments of a larger parent body shattered by ancient collisions, posed an immediate challenge for the mission team.