In the Vehicle Assembly Building at NASA's Kennedy Space Center, the top of external tank No. 120 is seen as the tank is lowered between the solid rocket boosters for mating on the mobile launcher platform. The external tank-SRB stack is being prepared for the orbiter Discovery, which will be mated to the stack in the VAB in two weeks. Space Shuttle Discovery is targeted to launch Oct. 23 on mission STS-120 to the International Space Station. Photo credit: NASA/George Shelton