In the Operations and Checkout Building Commander Mark Polansky checks the communication system in his helmet.

In the Operations and Checkout Building at NASA's Kennedy Space Center in Florida, STS-127 Commander Mark Polansky checks the communication system in his helmet. He and other crew members will be heading for Launch Pad 39A for a simulated launch countdown. The crew is at Kennedy for a launch dress rehearsal called the terminal countdown demonstration test, or TCDT, which includes emergency exit training and equipment familiarization. Endeavour's STS-127 mission is the final of three flights dedicated to the assembly of the Japanese Kibo laboratory complex on the International Space Station. Endeavour's launch is scheduled for June 13 at 7:17 a.m. EDT. Photo credit: NASA/Kim Shiflett