(Smithsonian Channel)

The American flag that Neil Armstrong and “Buzz” Aldrin planted on the moon in 1969 appeared to be blowing in the wind. Conspiracy theorists claim this is proof that the whole thing was staged — because there’s no wind on the moon.

The real story? A horizontal rod had been inserted through a hem at the top of the flag, but the astronauts had trouble pulling the telescoping rod all the way out, leading to that rippling effect. In other words, it was an engineering blunder.

And remarkably, it was one of only a handful connected to the first full deployment of the lunar module, which is the subject of the second episode of the new Smithsonian Channel six-part series “America’s Secret Space Heroes.”

Instead of focusing on astronauts, the show is about the behind-the-scenes folks, the ones who calculated on blackboards, toyed with cutting-edge technologies and cleaned up after experiments went awry.

Through archival footage, reenactments and interviews, viewers are transported back to the 1960s space race. The series’ premiere episode, which first aired May 14, explores the creation of the Saturn V rocket, a gigantic project that required a three-stage design and crazy-powerful engines. Residents in Huntsville, Ala., where testing was done, complained about their windows breaking and chandeliers coming apart.

The job of this rocket was to carry the lunar module, a comparatively dinky, bug-looking thing. But as the men who made the module explain in Episode 2, which airs May 21, there was no room for error in the vehicle, which had to perform under unknown conditions. (What is the lunar surface like? Um, not totally sure.)

And they had to seriously watch their weight. So plans calling for wide, helicopter-like windows were scrapped when that much glass was deemed too heavy. But the pilots needed to be able to see, so they were positioned standing up rather than seated and given small panels to look through.

The workarounds the design team created are now part of engineering — and American — history.