The Space Shuttle Discovery moved from the Orbiter Processing Facility to the Vehicle Assembly Building at Kennedy Space Center, Fla., to prepare for launch July 1, or in a window of July 1 through July 19, according to NASA.

This 12-day STS-121 mission to the International Space Station will involve a Discovery crew of seven who will test new hardware and techniques to improve shuttle safety, and deliver supplies to the station.

Work crews now are attaching a redesigned external fuel tank and twin solid rocket boosters to Discovery.

The redesign work was performed after an earlier mission, involving Space Shuttle Columbia, ended in disaster Feb. 1, 2003, when the shuttle burned up on re-entry, in which all seven crew members died. The crisis was caused by a large piece of foam breaking off and striking the leading edge of a wing on Columbia, which permitted the hot gases of re-entry to heat the inside of the wing until it failed structurally.