Researchers have developed a general framework to understand how granular asteroids resist breaking apart, revealing that the surface of asteroid Bennu is much softer than freshly ground coffee. The study shows that the strength of such asteroids depends on the cohesion between their grains, as well as the size and shape of the particles. By applying this model to data from Bennu samples, scientists estimate that the asteroid's surface tensile strength is less than 1 pascal—extremely weak compared to common materials. This finding is significant because it challenges the traditional view of asteroids as solid bodies, instead showing them as loosely bound collections of dust, rocks, and boulders held together mainly by gravity, with some help from cohesion and adhesion forces. The research focuses on asteroids like Bennu, Ryugu, Itokawa, Didymos, and Dimorphos, all of which are less than one kilometer in diameter. These small bodies are more likely to be held together by cohesive forces rather than gravity alone, especially as they spin. If an asteroid spins too fast, it could break apart, but smaller asteroids are less prone to this because their cohesion doesn't decrease as rapidly as their gravity. This means that cohesion can be the dominant force keeping them intact. To better understand the mechanical properties of these asteroids, an international team of researchers developed a model that uses the size and shape of the grains to predict their resistance. This model was tested using samples collected from Bennu by NASA’s OSIRIS-REx mission. In their simulations, researchers created a small fragment of Bennu by placing cohesive small grains—similar to the fine material that binds larger pieces together—between two large blocks. By pulling the blocks until the bridge of grains broke, they measured the tensile strength of the structure. They tested 78 different scenarios, varying the grains' size, shape, and distribution. The results showed that the strength of the bridge depended on both the size and shape of the grains. Smaller grains created stronger bridges, but spherical grains were less effective than angular ones due to fewer contact points. Interestingly, a bridge made of larger, angular grains could be just as strong as one made of smaller, rounded grains. Using this model, researchers estimated that Bennu’s surface is about 50 times weaker than ground coffee. This insight could help improve planetary defense strategies by providing better data on how to simulate and predict the behavior of asteroids during potential deflection missions. Future work aims to expand the model to study a broader range of grain sizes and internal structures within asteroids.