(11/10/1999) -- Inside the Vehicle Assembly Building, main engine No. 3 (left) is being removed from Space Shuttle Discovery. Last week, Shuttle managers determined that the engine was not acceptable for flight because a half-inch-long broken drill bit is lodged in the engine's coolant cavity. Therefore, the engine is being replaced. The Shuttle is expected to roll out to the pad at 2 a.m. Saturday morning, Nov. 13. The STS-103 launch is now targeted for Dec. 6 at 2:37 a.m. EST. The 10-day mission is expected to conclude at KSC on Dec. 16 with a 12:45 a.m. landing