NASA's space shuttle discovery rolls off launch pad tuesday

Space shuttle Discovery is scheduled to roll back from Launch Pad 39A to the Vehicle Assembly Building (VAB) at NASA's Kennedy Space Center in Florida for additional work related to its final scheduled mission. The first motion of the shuttle is targeted for 12:30 a.m. EST on Tuesday, Dec. 21.

In the VAB, technicians will scan below the foam insulation surrounding the intertank section of Discovery's external tank to look for any issues, such as cracks. They also will reapply foam after removing 89 sensors from the tank's aluminum skin following an instrumented tanking test on Dec. 17.

The sensors were used to measure changes in the tank as super-cold propellants were pumped in and drained out during the test. Data and analysis from the test will be used to determine what caused the tops of two, 21-foot-long support beams, called stringers, on the outside of the intertank to crack during fueling on Nov. 5.

Discovery's next launch attempt is no earlier than 1:37 a.m. on Feb. 3.

The fully assembled space shuttle, consisting of orbiter Discovery, the external fuel tank and twin solid rocket boosters, is mounted on a mobile launcher platform and will be returned to the VAB atop a crawler transporter. The crawler will travel slower than 1 mph during the 3.4-mile journey, which is expected to take about six hours.

Video highlights of the rollback will air on the NASA Television Video File segment Tuesday.