Navigating space is hard. It's expensive, complex, time-consuming and dangerous. And yet you have to hand it to Elon Musk: His SpaceX firm makes it look easy.

Space Exploration Technologies Corp.'s reusable Falcon 9 is today the world's rocket, a milestone in bringing down the cost of space transportation. It gives SpaceX a "de facto" monopoly on launch missions slinging payload like satellites into orbit. And that dominance extends to its own Starlink satellites, 6,000 of which orbit the Earth, offering high-speed internet almost anywhere. You don't need to believe in Musk's visions of humanity on Mars or (not-very-autonomous) to see the power of vertical integration at work; especially after ...