(04/08/2002) -- Making his fourth Shuttle flight, STS-110 Mission Specialist Steven L. Smith gives a thumbs up for the launch scheduled for 4:40 p.m. EDT. 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