STS-115 Mission Specialist Joseph Tanner (center) works a piece of equipment during Crew Equipment Interface Test activities in the Space Station Processing Facility. On the right is Mission Specialist Heidemarie Stefanyshyn-Piper. The mission will deliver the second port truss segment, the P3/P4 Truss, to attach to the first port truss segment, the P1 Truss, as well as deploy solar array set 2A and 4A. Launch on Space Shuttle Endeavour is scheduled for May 23, 2003.