To say "美国这颗卫星,虽然失控,但并不是无规则在做运动" means you have absolutely no clue about satellite. During de-orbit phase, the trajectory of satellite isn't that predictable. Basically the satellites will go through a serious orbit transfer, and its apogee and perigee interchanges. The drag force will also make the satellite tumbling around. It won't be just spiral down. The trajectory is an approximation, and it is no way to be accurate enough to intercept. That's why it requires optical tracker to track US 193 like it is a icbm.