In this historical photo from the U.S. space agency, inside the cavernous Vehicle Assembly Building, workers carry out the meticulous process of lifting the orbiter Discovery from a horizontal to a vertical position. Once upright, Discovery will be transferred into a high bay for mating with the external tank/solid rocket booster assembly already mounted on the mobile launcher platform.
Completing the assembly process takes about five working days. Discovery's next destination is Launch Pad 39B, and final preparations will be completed for liftoff on Mission STS-70 in early June.
Each weekday, SPACE.com looks back at the history of spaceflight through photos (archive).