SpaceX engines, Merlin & Raptor

SpaceX's dominance rests first on its engines: the reusable Merlin of the Falcon 9, produced on a line, and the methane Raptor of Starship, designed for industrial cadence. This vertical integration, design, foundry, testing at McGregor, is the barrier to entry its competitors struggle to clear. The flip side is an extreme concentration of Western propulsion know-how in a single company.