This photo reveals the area of a seal on space shuttle Discovery's right strut that was determined to be leaking.

This photo reveals the area of a seal on space shuttle Discovery's right main-gear strut that was determined to be leaking. United Space Alliance and B.F. Goodrich technicians are replacing the seal. The struts act as shock absorbers during the shuttle's landing. Engineers determined the observed leak of hydraulic fluid in the main landing gear strut exceeded specification and could not be reduced to an acceptable rate. Removing the strut and replacing seals require disconnecting and replacing the brakes and tires, disconnecting and reconnecting instruments and other requirements to allow access to the strut. Discovery had been scheduled to roll over Sept. 19 from its processing hangar to the Vehicle Assembly Building. A new rollover date will be set after technicians determine how long replacing the seal will take. Photo credit: NASA/George Shelton