Dressed in their launch and entry suits, STS-118 Pilot Charlie Hobaugh and Commander Scott Kelly (waving) are headed for the runway for landing practice in the shuttle training aircraft, known as an STA. The practice is part of Terminal Countdown Demonstration Test, or TCDT, activities that include a simulated launch countdown. The STA is a Grumman American Aviation-built Gulf Stream II jet that was modified to simulate an orbiter's cockpit, motion and visual cues, and handling qualities. In flight, the STA duplicates the orbiter's atmospheric descent trajectory from approximately 35,000 feet altitude to landing on a runway. The STS-118 mission is the 22nd flight to the International Space Station and is targeted for launch on Aug. 7. The mission payload aboard Space Shuttle Endeavour includes the S5 truss, a SPACEHAB module and external stowage platform 3. NASA/George Shelton