Donald Trump says America never wins at anything anymore, and that pessimism seems to fit the public mood even if it isn’t true. Consider the news that got lost over the holidays that a second American company has managed the feat of safely landing a rocket after a space flight.

SpaceX, Elon Musk’s space exploration company, successfully guided its Falcon 9 rocket back to Cape Canaveral late last month after it launched, traveled into space and re-entered the atmosphere. Mr. Musk said in a social media post over the weekend...