There is something about the speed of consensus on China’s rocket failures that should give us pause. Within hours of Long March-7A rocket’s disintegration over the South China Sea on August 10, trade reports were pointing to an engine as the likely culprit. The China Aerospace Science and Technology Corporation (CASC) had said nothing of the kind. An official Xinhua report about three hours after the launch described only “a flight anomaly” and an investigation under way. The cause is unknown,...