Seventy years ago, Earth had only one satellite: the moon. Now it has more than 15,000—about 10,000 of which are owned by Elon Musk’s SpaceX. The world’s first trillionaire plans to launch 1 million more satellites, each roughly 70 meters (230 feet) long and 20 meters (66 feet) wide, that would form a data center megaconstellation.