One place to view Orbiters is while they are moving out to or sitting on the launch pad. Roll out to the pad usually occurs during the early morning hours before sunrise when the winds are calmest. They occasionally run late and early bus tours get a good view as they make their rounds. Once on the pad, they spend most of the time covered by the Rotating Service Structure, seen to the left of the vehicle. Typically, the Orbiter is visible one day out of twenty until before launch.