(05/30/2002) - On Launch Pad 39A at 2:48 a.m. EDT, the Rotating Service Structure (left) begins rolling back from Space Shuttle Endeavour to allow launch preparations. At the lower left corner is seen the driver of one of the motor-driven trucks that move along circular twin rails installed flush with the pad surface. Endeavour rests on the Mobile Launcher Platform that straddles the flame trench below. The trench is 490 feet long, 58 feet wide and 40 feet high. STS-111 is the second Utilization Flight to the International Space Station, carrying the Multi-Purpose Logistics Module Leonardo, the Mobile Base System (MBS), and a replacement wrist/roll joint for the Canadarm 2. Also onboard Space Shuttle Endeavour is the Expedition 5 crew who will replace Expedition 4 on board the Station. The MBS will be installed on the Mobile Transporter to complete the Canadian Mobile Servicing System, or MSS. The mechanical arm will then have the capability to 'inchworm' from the U.S. Lab Destiny to the MSS and travel along the truss to work sites. Expedition 4 crew members will return to Earth with the STS-111 crew on Endeavour. Launch is scheduled at 7:44 p.m. EDT, May 30, 2002