Like a winged sentinel gleaming in white, the orbiter Atlantis made one last trek to the launch pad on Tuesday night to prepare for its July 8 blastoff — a final voyage for NASA after 30 years of space shuttle flights.
Atlantis began the slow crawl to Launch Pad 39A here at Kennedy Space Center at 8:42 p.m. ET, emerging from the massive 52-story Vehicle Assembly Building bathed in bright xenon spotlights.
The 3.4-mile (5.2-kilometer) journey to the seaside pad atop NASA's Apollo-era crawler transporter typically takes about six hours. Tuesday night's move, which was delayed slightly due to a hydraulic leak on the massive carrier, is the last trip any shuttle will take to the launch pad, since NASA will retire its space shuttle after Atlantis' flight. [Most Memorable Shuttle Missions]
Thousands of spectators turned out to watch Atlantis move to the pad for the very last time, and the four astronauts who will fly the shuttle's mission, which NASA calls STS-135, were on hand to mark the historic event.
"We're trying appropriately to recognize and mark these milestones, but at the same time, we're heads down, forward and very busy," Atlantis commander Chris Ferguson told reporters at a media event last week at NASA's Johnson Space Center in Houston.
Atlantis, the second oldest of NASA's space shuttles still flying, is scheduled to launch on the shuttle program's final mission no earlier than July 8. An official launch date will be announced by mission managers following a Flight Readiness Review on June 28.
The historic flight will be the 135th and final mission of NASA's space shuttle program, which began flying in 1981.
End of an era
With the shuttle program winding down, NASA employees have been able to invite family and friends to watch the shuttles roll to the launch pad for their final missions. The unique opportunity helps to boost morale as the program comes to a close, but also allows the shuttle workers to share the fruits of their labor with loved ones, NASA officials have said.
For the astronauts who will fly Atlantis on its final mission, paying tribute to these architects of the agency's 30-year shuttle program is important. [NASA's Space Shuttle – From Top to Bottom]
"We really want to recognize the folks in Houston who have provided decades of support for the space shuttle," Ferguson said. "Of course, the folks at KSC — several of whom have already received their layoff notices — who are, I think, bearing the lion's share of this drawdown into the post-shuttle era. We'll try to find a way to appropriately recognize and thank them."
During Atlantis' 12-day flight, the shuttle will deliver an experiment "to demonstrate and test the tools, technologies and techniques needed to robotically refuel satellites in space — even satellites not designed to be serviced," NASA officials said in a statement.
Ferguson, pilot Doug Hurley and mission specialists Rex Walheim and Sandy Magnus will also retrieve an ammonia pump that failed on the space station in July 2010. The failed pump module will return to Earth aboard Atlantis so that engineers can understand why the component failed.
STS-135 will be Atlantis' 33rd and final mission before it is retired, along with the rest of the agency's orbiter fleet.
Another shuttle set to land
Before Atlantis moved an inch toward its launch pad, the grounds at Kennedy Space Center were teeming with activity since another shuttle, Endeavour, is slated to land early Wednesday at the Florida spaceport.
Endeavour and its six-astronaut crew are scheduled to touch down on Runway 15 at the Shuttle Landing Facility at 2:35 a.m. ET Wednesday. [Photos: Shuttle Endeavour's Final Mission]
Endeavour is wrapping up its own 16-day mission, called STS-134, to the International Space Station — its final flight before being retired. The shuttle delivered a nearly $2 billion astrophysics experiment to the International Space Station, plus other supplies. The mission included four spacewalks, the last spacewalks ever for a shuttle crew.
NASA is retiring its 30-year shuttle program to focus on building spacecraft and launchers for future exploration missions beyond low-Earth orbit, such as to an asteroid and Mars.
Once Atlantis returns from its final flight, all three space-flown orbiters — Discovery, Atlantis and Endeavour — will be retired to museums for public display.
Atlantis, for its part, will stay in its Florida homeport. NASA is sending the shuttle to the Kennedy Space Center Visitor's Complex, next door to the agency's launch site.