These men's suits were built to last. They were pristine-white and composed of 20-plus layers of cutting-edge materials handcrafted into a 180-pound frame of armor. They protected the wearers from temperatures that fluctuated between −300 and 300 degrees Fahrenheit and from low atmospheric pressure that could boil away someone's blood. On a July day in 1969, the world watched intently as astronaut Neil Armstrong, wearing one of these garments, stepped off a ladder and onto a dusty, alien terrain, forever changing the landscape both of the moon and of human history. Few symbols of vision and achievement are more powerful than the Apollo mission spacesuits.

Back on Earth, the iconic garments found new lives as museum pieces, drawing millions to see them at the National Air and Space Museum in Washington, D.C. And staff members there have found, to their surprise, that the suits need their own life support. They are falling apart.

Last year Lisa Young, a conservator at the museum, noticed that a white, foggy bloom was beginning to creep across the transparent fishbowl helmets and that their smooth, curved surface was beginning to crack. “It is really frustrating,” Young says. “We had thought they were relatively stable.” There had been warning signs of suit trouble, though. The neoprene pressure bladders that kept astronauts' bodies from exploding in the vacuum of space began crumbling years ago, releasing acidic gases. “Anybody who has worked with the spacesuits knows their smell,” Young says. “I'd describe it as slightly pungent sweet chlorine.” And an orange-brown sticky stain began appearing on the exterior white fabric. ...