Space shuttle Discovery rolled out from its hangar for the last time early Thursday at NASA's Kennedy Space Center in Florida, beginning the first leg of its final mission into space.

The winged orbiter, the oldest of NASA's space shuttle fleet, emerged from its maintenance hangar at 6:30 a.m. EDT (1030 GMT) on its way to the nearby Vehicle Assembly Building. A water main break at the Florida spaceport on Wednesday forced NASA to delay the shuttle move by one day.

Once inside the cavernous 52-story building, Discovery will be attached to the twin solid rocket boosters and external fuel tank that will help launch it to the International Space Station on Nov. 1.

Discovery's final flight ahead

Discovery's upcoming STS-133 mission will mark the shuttle's 39th flight to space and NASA's 133rd shuttle flight since the fleet began space launches in 1981. It is NASA's second-to-last space shuttle mission before the fleet retires next year.

The shuttle Endeavour's STS-134 mission in late February 2011 is scheduled to be the final flight, though an extra mission on the orbiter Atlantis is under consideration. NASA is retiring its shuttle fleet to make way for a new plan to send astronauts to visit an asteroid by 2025.

Discovery's final spaceflight will deliver a storage room for the International Space Station and a humanoid robot assistant for the outpost's astronaut crew. But first, the shuttle had to leave its hangar to meet its fuel tank and rocket boosters.

Shuttle rollover history

Thursday's quarter-mile trip between its maintenance hangar and Vehicle Assembly Building was the 41st rollover in 26 years for Discovery, also known by its orbiter designation OV-103.

Discovery has more rollovers than actual space missions because the shuttle had to repeat the trip on two occasions: once for its maiden flight, STS-41D, in 1984 and again in 1991 before the STS-39 mission. In both cases, the re-rollover was due to Discovery needing repair before it could fly.

Thursday's journey was made atop the same 36-wheeled transport trailer that has moved Discovery -- and all of NASA's orbiters -- before each mission.

This latest rollover was originally planned for Wednesday morning but was delayed a day due to a water main break that forced NASA to close the space center to all but essential personnel. The burst 24-inch pipe, which was located nearby in  the VAB, was promptly addressed, allowing center operations to resume and the rollover to proceed this morning.

The trip between a shuttle hangar and the Vehicle Assembly Building typically takes about a half-hour to complete, but NASA parked Discovery outside its hangar for several hours to allow its employees – those who worked on the shuttle -- to pose with spacecraft for one last set of photos.

Once mated to its boosters and fuel tank -- an hours-long procedure assisted by a crane that is expected to be completed Friday morning -- Discovery will embark on a different type of roll.

The completely assembled shuttle stack will ride a massive Apollo-era crawler transporter to the 3.4-mile (5.4-km) trip to Launch Pad 39A. At the pad, Discovery will be readied for its November launch and loaded with its payload.

The launch pad rollout for Discovery is scheduled to begin late Monday, Sept. 20.

Click here for a photo gallery of Discovery's final rollover.

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