Discovery Shuttle Prepares to Roll Towards Launch Pad

Suspended from an overhead crane in the Vehicle Assembly Building at NASA’s Kennedy Space Center, the orbiter Discovery is lowered toward the Solid Rocket Booster and External Tank (seen below) already stacked on the top of the Mobile Launcher Platform (MLP). CREDIT: NASA/KSC.

NASA's space shuttle Discovery is poised to make an ever-so-slow trek Tuesday morning to the launch pad where it will rocket into orbit later this year.

Sitting inside the Vehicle Assembly Building (VAB) at NASA's Kennedy Space Center in Florida, Discovery is currently set to roll out to its launch pad at 6:00 a.m. EDT (1000 GMT).

The ever-so-slow trek is a major milestone in NASA's bid to return its shuttle fleet to flight since the loss of Columbia and its crew in 2003. The Discovery orbiter will launch STS-114, a test flight commanded by veteran astronaut Eileen Collins, which shuttle officials hope will prove the effectiveness of new tools and techniques aimed at improving shuttle safety.

Discovery is set to make the 4.2-mile journey from the VAB to Launch Pad 39B in about eight hours. Shuttle engineers and technicians have spent the last week attaching the orbiter to its external tank and boosters, as well as installing new cameras to observe the tank during launch.

Discovery's STS-114 spaceflight is currently set to launch no earlier than May 15, though the mission has a launch window that is open through June 3. A second launch opportunity - currently allotted to the STS-121 mission aboard Atlantis - opens on July 12.  

Both launch windows take into account flight restraints that call for daylight liftoffs for NASA's first two return-to-flight shuttle launches. The launch restraint is designed to provide the best observation opportunities to study the orbiter and its external tank during ascent.