Mission Specialist Dave Williams is eager to start the simulated launch countdown that concludes the terminal countdown demonstration test.

STS-118 Mission Specialist Dave Williams, who represents the Canadian Space Agency, is eager to start the simulated launch countdown that concludes the terminal countdown demonstration test, or TCDT. The STS-118 crew has been at Kennedy for the TCDT activities that also include M-113 training, payload familiarization and emergency egress training at the pad. The mission is the 22nd flight to the International Space Station and Space Shuttle Endeavour will carry a payload including the S5 truss, a SPACEHAB module and external stowage platform 3. STS-118 is targeted for launch on Aug. 7. Photo credit: NASA/George Shelton