A darkening cloud overhead keeps vigil as Space Shuttle Atlantis moves away on its rollback to the Vehicle Assembly Building.

A darkening cloud overhead keeps vigil as Space Shuttle Atlantis moves away from Launch Pad 39B on its rollback to the Vehicle Assembly Building. At right are the rotating and fixed service structures. First motion off the pad was at 10:04 a.m. EDT. The crawler is 131 feet long, 113 feet wide and 20 feet high. It weights 5.5 million pounds unloaded. The combined weight of crawler, mobile launcher platform and a space shuttle is 12 million pounds. Unloaded, the crawler moves at 2 mph. Loaded, the snail's pace slows to 1 mph. The rollback is a safety precaution as the area waits for the arrival of Tropical Storm Ernesto. The storm is forecast to be bringing 58-mph to 70-mph winds in the next 24 hours. The shuttle will be moved into high bay 2, on the southwest side of the VAB, for protection from the storm. Photo credit: NASA/Ken Thornsley