So Neal had started to pursue another avenue. Using his new role as part of the White House Science Advisory Team, he had parlayed access to several super-telescopes in Hawaii, the Philippines, Chile, and Australia. Using the combined imagery from all of them he began to set up a triangulated image of anything that was nothing. Armed with the knowledge that the satellites were cloaked beyond any capability we had to actively track them, he had instead used that fact against them and tracked pieces of near space that were blank, seeking moving patches where stars momentarily vanished, or, disconcertingly, seemed to shimmer, even if only for a fraction of a second. Taken in isolation these instances would provide little or no solid information, but taken as a whole they began to show paths in the sky. They were certainly very slippery, but once consecutive hits on each satellite started to come, he was able to plot an initial track using this passive method.

Eventually he had mapped the exact orbits of each of the four craft, and all without using any active radar. But the complexity of the process had only improved his respect for the advanced team’s abilities. They had not made it easy.

As Earth’s rotation gives the equator a relative speed of about one thousand miles per hour west to east, it is far easier for us when launching a satellite to use that latent speed as a catapult, so that we only have to gain roughly five to ten thousand miles per hour more to reach the relative speeds needed to enter low to mid-earth orbit. To go the other way would be like paddling upstream: you would have to work that much harder just to lose the momentum you already had from launching from Earth’s moving surface.

But an object arriving from somewhere other than Earth did not have to worry about accelerating into orbit, only decelerating. Unaffected by the earth’s natural spin, they had used this freedom and designed their satellites’ approach vectors to make the orbits retrograde: going against the earth’s spin.

It meant that no spot was ever far from their view, Earth revolving beneath them as they circled it in the other direction. Orbiting just above the Hubble telescope and Iridium satellites in low-earth orbit, the AI satellites moved at just over fifteen thousand miles per hour, using the additional rotational speed of Earth below them to allow a rapid, virtually constant vigil over the bulk of humanity. Each satellite passed the same point on the planet below every three hours, and that same point was also passed over three other times by the three other satellites during that time.