^^^Strictly speaking, the explosion that started the cascade would have imparted delta vee to the fragments, thereby changing the orbits. The whole idea of the cascade is SF construed in the narrowest sense, a speculative idea in science or technology used as a narrative device.
I still insist that the worst science is the ghost. And even if you try to interpret that as an hallucination caused by anoxia, I still insist that anoxia does not give you life-saving ideas! Everything being conveniently close is trivial by comparison.