(11/10/1999) -- Inside the Vehicle Assembly Building, main engine No. 3 (bottom right) is being removed from Space Shuttle Discovery. Above it are (left) the Orbital Maneuvering System (OMS) engine, the reaction control thrusters (right), and the OMS pod (top). 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