The space suit above was built as a demonstration suit for testing in a vacuum chamber at NASA's Ames Research Center.

The chamber was designed to simulate the environment in outer space. Astronauts would get into their suits, hook themselves up to oxygen, and then go into the vacuum chamber, which simulated the environment at an altitude of 400,000 feet (121 kilometers).

"They were then asked to do repetitive and somewhat mind-numbing tasks, like walking up and down on a crate, so that technicians could check their suits," said Lewis.

Though the space program was relatively young in the late 1960s when this suit was developed, it was building off of almost 20 years of experience with hardened suit designs. They were originally made for the U.S. Air Force in the early 1950s, back when the Air Force used vacuum tubes in aircraft. (See pictures of early U.S. spaceflight.)

"But many of the vacuum tubes were failing," said Lewis. "And they needed to figure out why."

Enter Litton Industries. The large defense contractor, which was bought by Northrop Grumman Corporation in 2001, designed a vacuum chamber to test why the vacuum tubes were failing. But to do that, they needed to design a suit for a technician to wear while inside the vacuum chamber.

"The Air Force was intrigued," said Lewis. "Even after they discontinued the use of vacuum tubes in aircraft, they continued to fund Litton's suits. And when NASA formed [in 1958], they took over much of the research in suit development from the Air Force."

In the years that followed, hundreds of people worked on space suits: Engineers designed the suits, technicians tested them, manufacturers created the parts, and then other folks assembled the final product.

"You can't tell by the x-ray, but some of the components are hand-sewn," said Lewis.

Pictures: What's Inside a Space Suit? X-Rays Reveal All

New x-rays of space suits show the inner workings that helped astronauts safely explore the cosmos.