Tony Antonelli and Mission Specialist Richard Arnold are getting ready to enter the open hatch into space shuttle Discovery.

In the White Room on Launch Pad 39A at NASA's Kennedy Space Center in Florida, STS-119 Pilot Tony Antonelli (center) and Mission Specialist Richard Arnold are getting ready to enter the open hatch into space shuttle Discovery. The White Room is at the end of the orbiter access arm on the fixed service structure and provides access into the shuttle. The STS-119 mission is the 28th to the International Space Station and the 125th space shuttle flight. Discovery will deliver the final pair of power-generating solar array wings and the S6 truss segment. Installation of S6 will signal the station's readiness to house a six-member crew for conducting increased science. Liftoff is scheduled for 7:43 p.m. EDT. Photo credit: NASA/Tony Gray, Tom Farrar