Sixty years ago this week, the Soviet Union launched the world’s first satellite into orbit, changing the course of history. The race for space was on, and the Soviets had taken an early lead. But the sight of Sputnik blinking across the October sky spurred Americans to action. Twelve years later, with “one giant leap for mankind,” the U.S. claimed its rightful place as the undisputed leader in the exploration of the heavens.

That pre-eminence in outer space is now under threat—and once again, America must act. President Trump...