...And Let Slip the Dogs of War
Already knowing that the remaining satellites were currently unreliable due to all the jamming and other electronic warfare happening in orbit, the missiles had been programmed with strict courses. Thus, the accuracy should be decent enough to saturate such a large target; the total area they were aiming at was the size of Australia, after all. So the missiles were using initial position determination. The blanket of shrapnel orbiting the planet prevented most forms of celestial navigation from working, so the missiles had to rely on IPD, which was made possible by accelerometers and gyroscopes working together along with knowing the initial launch coordinates to determine where the missile isn’t, thus telling it where it is.