Asteroid Bennu surface found to be extremely fragile

Researchers led by Paul Sánchez from the University of Colorado Boulder have determined the structural fragility of the asteroid Bennu, providing critical data for future planetary defense strategies. The study, published in Nature Communications, reveals that Bennu’s surface is exceptionally weak—weaker than freshly ground coffee—with a strength of less than one pascal.

By analyzing samples returned by NASA’s OSIRIS-REx mission, the team developed a new method to predict the strength of granular asteroids. Unlike previous simulations that treated particles as perfect spheres, this new model accounts for irregular, angular shapes. The researchers used a “granular bridge” computer model, simulating layers of particles between large boulders to measure tensile strength.

The findings indicate that an asteroid’s strength is dictated by particle size and shape. Smaller particles create stronger structures due to a higher number of contact points. This understanding is vital for calculating the force required to deflect similar asteroids should they pose a threat to Earth.