On March 17, space shuttle Atlantis was moved into Kennedy Space Center's 52-story Vehicle Assembly Building from its processing hangar. Workers in the VAB attached Atlantis to its external fuel tank and solid rocket boosters atop a mobile launching platform. In addition, one of the main engines was replaced due to concerns about internal seals. Images: NASA/KSC.

Attaching the crane Inside the Vehicle Assembly Building, Atlantis rests atop a transporter in the transfer aisle while an overhead crane is placed around the space vehicle.
Going vertical The overhead crane begins to lift Atlantis into a vertical position so it can be mated with its external tank and solid rocket boosters before being transported to launch pad 39A.
Shuttle belly The belly of Atlantis is seen after the shuttle is raised vertically. The landing gear doors are clearly noted and the two external tank umbilical doors are opened for the upcoming mating.
Hoisting high Suspended by a crane over the transfer aisle of the VAB, Atlantis is lifted higher in order to move it toward the stack of external tank and solid rocket boosters at left. The 122-foot high orbiter is easily accommodated inside the 525-foot-tall, 518-foot-wide VAB.
The High Bay The crane maneuvers Atlantis into High Bay 3. The awaiting external fuel tank and solid rocket boosters are seen atop the mobile launcher platform.
Sliding down Technicians slowly lower Atlantis in front of the external fuel tank. The shuttle mating process takes several hours from start to finish.
Almost there Atlantis is nearly in place next to the attach points on the external tank. Workers would then physically bolt the shuttle the to tank and connect fuel and electrical lines.
Engine out Equipment is positioned to remove main engine No. 1 from Atlantis in the VAB. An inventory review revealed the engine probably had defective engine fuel pump tip seals accidently installed.
New engine installed Underneath the 26-foot vertical tail structure of Atlantis, workers prepare to install the replacement main engine No. 1. The main engine nozzles, visible in the photo, are 7.8 feet across and 9.4 feet high.