Since the Earth had never before been bombarded by a vast barrage of lunar fragments, there was no way to predict what it was going to be like. Statistical models had been occupying much of Doob’s time because they had a big influence on which scenarios might be most worth preparing for. To take a simplistic example, if the moon could be relied on to disassemble itself into pea-sized rocks, then the best strategy was to remain in place and not worry too much about maneuvering. It was hard to detect a pea-sized bolide until it was pretty close, by which time it was probably too late to take evasive action. A strike from a rock that size would perforate an arklet or a module of Izzy, but not destroy it; people might get hurt and stuff might get broken, but the worst case was that a whole module or arklet would be destroyed with the loss of a few lives. On the other hand, in the more likely scenario where the Hard Rain included rocks the size of cars, houses, and mountains, detection from a distance would be easier. Evasive action would be not only feasible, but obligatory.