When American astronauts landed on the moon in 1969, one of their first tasks — after grabbing a handful of moon rocks in case they needed to make a sudden departure — was to raise “Old Glory” above the lunar plain.

It wasn’t a standard American flagpole, which would have let the fabric droop and sag in the airless, breezeless vacuum of space. So the design included not just an upright pole but a perpendicular extension like a shower curtain rod, so the flag could hang fully unfurled, all its stars and stripes showing.