A United Space Alliance technician examines one of shuttle Atlantis' thermal protection tiles in Orbiter Processing Facility 1 at NASA's Kennedy Space Center.

A United Space Alliance technician examines one of shuttle Atlantis' thermal protection tiles in Orbiter Processing Facility-1 at NASA's Kennedy Space Center in Florida. The tile went through a pull test, which measured the force it took to pull it off of the shuttle in order to make sure the bond between the two is strong enough to withstand the force of launch and landing. Atlantis is being prepared for the STS-135 mission, which will deliver the Raffaello multipurpose logistics module packed with supplies, logistics and spare parts to the International Space Station. STS-135 is targeted to launch June 28, and will be the last spaceflight for the Space Shuttle Program. Photo credit: NASA/Jack Pfaller