(12/03/2001) -- After rollback of the Rotating Service Structure on Launch Pad 39B, Space Shuttle Endeavour is bathed in light. Twin solid rocket boosters flank the orange external tank behind Endeavour. Above the external tank is the Gaseous Oxygen Vent Arm that vents gaseous oxygen vapors away from the Shuttle. The vent hood assembly at the end is often referred to as the 'beanie cap.' Stretching to the crew hatch on the side of Endeavour is the Orbiter Access Arm with its environmentally controlled White Room at the end, through which the crew enters the vehicle. The Shuttle sits on the Mobile Launcher Platform with the two service tail masts on either side of the main engines. The tail masts support the fluid, gas and electrical requirements of the orbiter's liquid oxygen and liquid hydrogen aft T-0 umbilicals. Each tail mast is 31 feet (9.4 meters) high, 15 feet (4.6 meters) long and 9 feet (3.1 meters) wide. Endeavour is scheduled to launch on mission STS-108 Dec. 4 at 5:45 p.m. EST. On this 12th flight to the International Space Station, known as a Utilization Flight, Endeavour will carry a crew of four plus the Expedition 4 crew, who will replace Expedition 3 aboard the ISS. The payload includes the Multi-Purpose Logistics Module Raffaello, filled with supplies, equipment and experiments