Facility 3 a technician makes a fit check of boundary layer transition tile underneath space shuttle Discovery.

In Orbiter Processing Facility 3 at NASA's Kennedy Space Center, a technician makes a fit check of boundary layer transition tile underneath space shuttle Discovery. Scheduled to launch on the STS-119 mission, Discovery will carry the S6 truss segment to complete the 361-foot-long backbone of the International Space Station. The truss includes the fourth pair of solar array wings and electronics that convert sunlight to power for the orbiting laboratory. Discovery is targeted to launch Feb. 12, 2009. Photo credit: NASA/Jim Grossmann