Facing what could be the final voyage in its quarter-century of spaceflight, the shuttle Atlantis emerged from Kennedy Space Center's assembly building bathed in spotlights and traveled to the launch pad overnight.

Check out Spaceflight Now's two photo galleries of Atlantis' rollout:

• Atlantis embarks on rollout
• Inside the Vehicle Assembly Building
• Shuttle perched atop pad 39A
• Crew chats with news media

The trip covering 3.5 miles along the rock-covered road began at 11:31 p.m. and concluded at 6:03 a.m. EDT when the mobile launching platform was securely anchored to pad 39A. The rollout was delayed twice by lightning concerns on Monday and Tuesday nights, then by soggy conditions on the crawlerway early Wednesday.

Atlantis entered service with a classified Defense Department mission in October 1985 that deployed a pair of military communications satellites. Since then, the orbiter has flow 30 more times on a variety of flights that launched the Magellan radar mapper to Venus, the Galileo orbiter to Jupiter and the Gamma Ray Observatory to survey the cosmos, built U.S.-Russian relations with multiple dockings to the space station Mir, completed critical sorties to construct the International Space Station and extended the life of NASA's Hubble Space Telescope.

Credit: Justin Ray/Spaceflight Now

What's currently the last scheduled flight of the venerable spaceplane, Atlantis will blast off May 14 at 2:19 p.m. EDT carrying a Russian docking module to the International Space Station on mission STS-132.

But whether it's truly the final time Atlantis will circle the planet depends if NASA approves the addition of one more mission to the the space shuttle manifest. That flight, known as STS-135, would use the extra external fuel tank and solid rocket boosters available to the shuttle program.

No decisions have been made to authorize the bonus flight, leaving the Atlantis team well aware that Thursday's rollout might have been the historic last before the orbiter is retired.

"The manifest hasn't changed. STS-132 is still the last flight of Atlantis," said Mikes Moses, the shuttle launch integration manager.

After Atlantis lands in late May, KSC workers will put the orbiter into normal post-flight turnaround activities and ready it for duty as a rescue vehicle.

NASA has prepared "launch-on-need" shuttles throughout the post-Columbia era in case an orbiting astronaut crew needs rescued. Since the space agency will have the hardware available to stage a rescue of what's presently the final shuttle mission this fall, some have urged the program to launch that standby vehicle later on a standard mission, albeit with a smaller crew, and deliver more supplies to the International Space Station.

If NASA opts to add the STS-135 mission, then Atlantis would see one more journey after all.

"It will be readied as a rescue vehicle, if needed. There has been a lot of talk from the administration, politically, whether you go ahead and fly that rescue vehicle since you have the hardware here and stacked. But there has been no decision made there," Moses.

In any event, Atlantis' upcoming trek will help expand the Russian segment of the International Space Station with delivery of the Mini Research Module 1 that gets attached to the Earth-facing port of Zarya. Once fully activated, the module becomes a new docking compartment for visiting Russian spacecraft.

Credit: Justin Ray/Spaceflight Now See crew at the pad photo gallery

Atlantis' 12-day voyage includes three spacewalks to replace a half-dozen aging batteries on the station's Port 6 power truss, install a new space-to-ground communications antenna dish and boom on the Z1 truss and add a small platform onto the Canadian Dextre robot.

Astronaut Ken Ham commands this 32nd flight of Atlantis. He'll be joined by pilot Tony Antonelli and mission specialists Garrett Reisman, Mike Good, Steve Bowen and Piers Sellers.

The six men were among the spectators on hand Thursday to watch Atlantis' journey to the launch pad.

"We ended up staying for hours because it is absolutely incredible," Ham said. "It was one of those moments we shared with each other to remind us of the reality of what we're going to go do."

Following a launch May 14, the shuttle is scheduled to dock with the space station around 10 a.m. EDT on May 16. The first spacewalk starts around 8 a.m. May 17 to handle the new antenna and Dextre equipment installation tasks. Mini Research Module gets attached the morning of May 18 and the crew will ingress it on May 20.

The second and third EVAs begins just after 7 a.m. May 19 and May 21, respectively, to perform the P6 battery replacement effort.

Atlantis undocks around 11 a.m. May 23 and returns to Earth with a landing at Kennedy Space Center on May 26 at approximately 8:30 a.m. EDT.