Shuttle Discovery Begins Slow Crawl Off Launch Pad

– On Launch Pad 39B, Space Shuttle Discovery is revealed after rollback of the Rotating Service Structure. The Orbiter Access Arm can be seen extended to the cockpit. Discovery will be rolled back to the Vehicle Assembly Building. Once inside the VAB, Discovery will be demated from its External Tank and lifted into the transfer aisle. CREDIT: NASA/KSC.

CAPE CANAVERAL - Shuttle Discovery is headed back to the Vehicle Assembly Building, where a new set of booster rockets and external fuel tank are waiting.

The crawler-transporter moved its first few inches on the pad at 6:44 a.m., beginning a journey that will last at least six-and-a-half hours.

Rollback was to start around 2 a.m., but delays finalizing engineering paperwork held up those plans.

In the VAB over the next couple of weeks, Discovery will be mated with a new fuel tank outfitted with a heater designed to prevent ice from forming.

Ice and insulating foam, like the piece that caused a deadly breach in Columbia's wing, are the most common sources of dangerous debris that can come off the tank and boosters during launch.

Tests reveal that, without the new heater, ice buildup on a pipeline outside the tank could be a problem as it is filled with supercold rocket propellants.

On Wednesday, workers tested Discovery's auxiliary power units, which run the hydraulic system that helps steer the orbiter. The test showed no signs of problems, KSC officials said.

Inspections of the ship's landing-gear also found no problems. A small crack on sister ship Atlantis prompted the checkup.

Unlike Atlantis, "inspections at this point show there are no indications of any cracks in that area," NASA spokeswoman Jessica Rye said.

Discovery rolled out to pad 39B on April 6. If all goes as planned, the shuttle will roll out to the pad again in mid-June. NASA officials hope it will fly during a launch window that opens July 13.

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