Tony Antonelli checks a mirror as he prepares for a simulated launch countdown as part of the prelaunch preparation known as Terminal Countdown Demonstration Test.

Seated in space shuttle Discovery on Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-119 Pilot Tony Antonelli checks a mirror as he prepares for a simulated launch countdown as part of the prelaunch preparation known as Terminal Countdown Demonstration Test. The TCDT also includes equipment familiarization. Discovery is targeted to launch on the STS-119 mission Feb. 12. During the 14-day mission, the crew will install the S6 truss segment and solar arrays to the starboard side of the International Space Station, completing the station's truss, or backbone. Photo credit: NASA/Kim Shiflett