Watch the movement of the RSS Live above.
The Rotating Service Structure began moving at 11:58 p.m. EDT.
The rotating service structure is 102 feet long, 50 feet wide, and 130 feet high. It is supported by a rotating bridge that pivots about a vertical axis on the west side of the pad’s flame trench. The structure rotates through 120 degrees — one third of a circle — on a radius of 160 feet. Its hinged column rests on the pad surface and is braced against the fixed service structure.
The rotating service structure provides protected access to the orbiter for installation and servicing of payloads at the pad, as well as servicing access to certain systems on the orbiter. The majority of payloads are installed in the vertical position at the pad, partly because of their design and partly because payload processing can thus take place further along in the launch processing schedule.