At NASA's Kennedy Space Center in Florida flags wave briskly on Launch Pad 39A.

At NASA's Kennedy Space Center in Florida, flags wave briskly on Launch Pad 39A. The rotating service structure (RSS) was rolled away from space shuttle Endeavour in preparation for the shuttle's upcoming launch. Retraction of the structure, which provides weather protection and access to the shuttle, began at 11:44 a.m. EDT and was completed at 12:24 p.m.

RSS "rollback" marks a major milestone in Endeavour's STS-134 mission countdown. Liftoff is scheduled for May 16 at 8:56 a.m. EDT. Endeavour and its crew will deliver the Express Logistics Carrier-3, Alpha Magnetic Spectrometer-2 (AMS), a high-pressure gas tank and additional spare parts for the Dextre robotic helper to the station. This will be the final spaceflight for Endeavour. For more information visit, www.nasa.gov/mission_pages/shuttle/shuttlemissions/sts134/index.html. Photo credit: NASA/Kim Shiflett