The main-gear assembly is used to absorb the impact of landing of the space shuttle on the runway at the end of its mission. The landing gear is lowered in preparation for landing while the space shuttle is approaching the runway at about 265 miles per hour (430 kilometers per hour).

The shuttle has three landing gear assemblies, one in the nose and two main ones—one under each wing. Each assembly has two tires. When the assemblies are extended for landing they descend to the down position with the use of hydraulic power and springs. When fully deployed, they lock into place ready to absorb the weight of the orbiter during its landing.

Engineers attempted to fix the problem without replacing the defective seals, but were unsuccessful. To fix the problem by replacing the seals, engineers will need additional time from what was already allotted, which could possibly delay the launch date by up to a few days.

The replacement of the seals is now scheduled to begin around the middle part of next week. It entails removing the shuttle’s brakes, wheels, and tires in order to access the seals.

NASA officials state that it is undecided at this time if a delay will be needed in the launch of the mission. Obviously more will be known as engineers work on the repair and determine the extent of the job.

Discovery and its STS-120 crew are currently scheduled to lift off on October 23, 2007.


{moscomment}