The orbiter access arm is positioned against Space Shuttle Endeavour after rollback of the rotating service structure.

The orbiter access arm is positioned against Space Shuttle Endeavour after rollback of the rotating service structure, or RSS, on Launch Pad 39A. At the end of the arm is a clean room from which the astronauts enter the crew compartment of the orbiter for launch. Rollback started at 9 p.m. EDT Aug. 7 and was complete at 10:40 p.m. The RSS provides protected access to the orbiter for changeout and servicing of payloads at the pad. Rollback of the pad's RSS is one of the milestones in preparation for the launch of mission STS-118 at 6:36 p.m. EDT on Aug. 8. Space Shuttle Endeavour's STS-118 mission is the 22nd shuttle flight to the International Space Station. It will continue space station construction by delivering a third starboard truss segment, S5, and other payloads such as the SPACEHAB module and the external stowage platform 3. Photo credit: NASA/Kim Shiflett