Mission STS-115 training exercises culminated Thursday in Florida with a launch dress rehearsal and simulated countdown with the look and feel of a real launch day. The astronauts suited up in their familiar bright-orange launch and entry suits before leaving for the launch pad aboard the "Astrovan," just as they will on launch day. At the pad, they were strapped in their seats aboard the Space Shuttle Atlantis as the launch team took them through the mock countdown.

After the countdown rehearsal, the crew members had a chance to check the mission payload, already stowed in Atlantis' cargo bay, before departing in T-38 jets from the Shuttle Landing Facility for their trip back to Houston.

Earlier in the week, the astronauts practiced emergency escape methods involving the baskets and slidewires and the M-113 armored personnel carriers that could rapidly take them away from the launch pad area in the event of an emergency. Commander Brent Jett and Pilot Chris Ferguson practiced landings at the Shuttle Landing Facility using the training aircraft. The crew paused during the week's activities to hold a question-and-answer session for representatives from the news media.

The STS-115 crew consists of Commander Brent W. Jett Jr., Pilot Christopher J. Ferguson and Mission Specialists Heidemarie M. Stefanyshyn-Piper, Joseph R. Tanner, Daniel C. Burbank and Steven G. MacLean, who represents the Canadian Space Agency.

During their 11 days in space, the astronauts will install the integrated P3/P4 truss segment with its two large solar arrays that will provide one-fourth of the total power generation capability of the completed station.