On Launch Pad 39A the payload canister approaches the waiting payload changeout room in the rotating service structure.

On Launch Pad 39A at NASA's Kennedy Space Center, the payload canister approaches the waiting payload changeout room in the rotating service structure. The canister will be lifted up to the changeout room and the payload transferred inside. The changeout room is the enclosed, environmentally controlled portion of the service structure that supports cargo delivery to the pad and subsequent vertical installation into an orbiter's payload bay. From the payload changeout room, the pressurized module and RMS then will be transferred into space shuttle Discovery’s payload bay. Launch is targeted for May 31. Photo credit: NASA/Kim Shiflett