STS-110 Mission Specialist Steven Smith gives a thumbs up for launch as he has a final check of his launch and entry suit. This flight will be his fourth. The STS-110 payload includes the S0 Integrated Truss Structure (ITS), the Canadian Mobile Transporter, power distribution system modules, a heat pipe radiator for cooling, computers and a pair of rate gyroscopes. The 11-day mission is the 13th assembly flight to the ISS and includes four spacewalks to attach the S0 truss to the U.S. Lab Destiny. Launch is scheduled for April 4