The crawler-transporter with the shuttle stack on board will require about six hours to make the 3.4-mile journey from the Vehicle Assembly Building to the pad. The mission payload, consisting of the S6 truss segment and U.S. solar arrays which was delivered to the pad earlier in the week, was transferred to the pad's changeout room. The changeout room is the enclosed, environmentally controlled area of the rotating service structure that supports cargo delivery to the pad and installation into the shuttle's payload bay. At NASA's Johnson Space Center in Houston, the STS-119 mission astronauts are in the Neutral Buoyancy Laboratory practicing techniques they'll be performing on the mission's fourth spacewalk.
(Image: At Kennedy's Launch Pad 39A the open doors of the payload canister reveal the S6 integrated truss structure and U.S. solar arrays for the STS-119 mission. Photo credit: NASA/Chris Rhodes)