(04/08/2002) -- During suitup for launch, STS-110 Mission Specialist Rex J. Walheim smiles in anticipation of his first Shuttle flight. STS-110 is the 13th assembly flight to the International Space Station, carrying the S0 Integrated Truss Structure and Mobile Transporter (MT). On the 11-day mission, the mission features four spacewalks to attach the S0 truss, which will become the backbone of the Space Station, to the U.S. Lab, 'Destiny.' The MT, a space 'railcar,' is attached to the truss segment and will make its debut run during the flight. Launch is scheduled for 4:40 p.m. EDT (20:40 GMT)