In this historical photo from the U.S. space agency, two men standing on the lily pad in 1959, guiding a crane to remove the third of the three large, white twenty-ton shrapnel shields that nest over the pressure tank. The shields were then stacked off to the side until it was time to reposition them on top of the pressure tank.
Since the support beams could rotate 365 degrees, the overhead crane could reach any location in the containment vessel. The pressure tank hatch is open.
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Each weekday, SPACE.com looks back at the history of spaceflight through photos (archive).