The Saturn V flew for the first time today.

Apollo 4. All three stages, no crew, unmanned test. The Saturn V launched from Pad 39A at Kennedy Space Center, flew its full profile — first stage separation, second stage, third stage translunar injection — and the command module re-entered at near-lunar return velocity to test the heat shield.

It worked. All of it. On the first attempt.

The noise reportedly shook buildings miles away. The acoustic engineers had underestimated the sound intensity at the press site three miles from the pad; reporters and observers who were watching had windows rattle out of buildings and one woman had a ceiling tile fall on her. The shockwave from the exhaust hit the press site and felt, they said, like a punch in the chest. The ground shook. Camera equipment was jarred loose.

I wasn’t there. I was in Ohio, watching coverage on television. But the correspondents who were there described it in terms that make me wish I had been: a sound that was not sound exactly but a physical pressure, a vibration that you felt in your sternum and your fillings, the ground moving. Five F-1 engines, each producing 1.5 million pounds of thrust, all firing at once. 7.5 million pounds of thrust total.

The “all-up” testing philosophy is what makes this remarkable. Previously, complex multi-stage rockets were tested stage by stage, validating each component before integrating the whole. George Mueller, who runs the Office of Manned Space Flight, insisted on testing the whole Saturn V system at once — all stages, live, in one flight. The engineers hated this idea; conventional wisdom said you’d never know what caused a failure if everything was flying at once. Mueller said there was no time for conventional wisdom; the deadline was 1969.

And it worked. First flight. All systems nominal.

The schedule has been saved, or at least has a path back. If Apollo 5 (unmanned lunar module test) goes well, and Apollo 6 (another unmanned Saturn V test), then Apollo 7 can be crewed. We might make 1969 after all.

The Saturn V worked on its first try.

I’ve been waiting for a piece of unambiguous good news for most of this year. Today I got it.