He walks through the evidence of asteroid Itokawa, a rubble pile discovered in 1998. It's 1,100 feet along its long axis, and the key detail is this: it's not a single coherent object. What holds it together is gravity, possibly supplemented by some kind of cementitious material binding the fragments. You can see smooth areas that suggest fine-grained material, almost like a natural glue. The structure itself is a conglomerate, a collection of debris that accumulated and stuck together over time. This changes how we think about asteroid composition and collision dynamics. If many near-Earth objects share this rubble pile structure, their behavior under stress or impact becomes far more unpredictable than a solid rock would be.