The orbiter, SRBs, and ET are mated in the Vehicle Assembly Building;
the fourth largest building (by volume) in the world. It encloses
130 million cubic feet. Each star on the US flag painted on the outside
of the building is six feet across; the blue field of stars is the size of
a basketball court. Without the building's moisture reduction systems,
clouds and rain would form inside it. During mating, the orbiter, SRBs,
and ET are moved across the building and flipped about
by cranes at the ceilings. The VAB was built for the vertical assembly
of the Saturn V rocket, adapted for the Shuttle Program, and will
soon be used for the Constellation Program's Ares rockets.