Atlantis launched into an almost clear Florida sky this morning for an 11-day mission that marks the return to assembly of the International Space Station. Today marks the first time in almost four years that a major new space station component has been launched. Atlantis’ mission begins a series of complex station expansion missions that will be among the most challenging spaceflights in history. Commander Brent Jett, Pilot Chris Ferguson and Mission Specialists Heidemarie Stefanyshyn-Piper, Joe Tanner, Dan Burbank and Steve MacLean, a Canadian Space Agency astronaut, lifted off at 10:15 a.m. CDT. The launch followed a flawless countdown. During the climb to orbit, Mission Control asked the crew to reconfigure a cooling system that apparently had ice build up. The reconfiguration cleared the system, called the Flash Evaporator System, and it operated normally. Temporary ice in that cooling unit is not uncommon and has occurred on previous missions. Moments after main engine cutoff, 8.5 minutes after liftoff, Tanner and MacLean used handheld video and digital still cameras to document the external tank after it separated from the shuttle. That imagery, as well as imagery gathered by cameras in the shuttle’s umbilical well where the tank was connected, will be transmitted to the ground for review. As Atlantis launched, the space station was 220 miles above the northern Atlantic Ocean, between Greenland and Iceland. Aboard the outpost are Expedition 13 Commander Pavel Vinogradov, a Russian cosmonaut; Flight Engineer and NASA Science Officer Jeff Williams; and Flight Engineer Thomas Reiter of the European Space Agency. They watched the launch via a live television transmission from Houston. Atlantis is set to dock to the complex at about 5:46 a.m. CDT Sept. 11. Atlantis’ crew will install the 17.5-ton, bus-sized P3/P4 integrated truss section to the station that includes a second set of solar arrays, batteries and associated electronics. The addition eventually will double the station’s capability to generate power from sunlight. The girder-like P3/P4 truss is 45 feet long. Three spacewalks are planned to install the truss, deploy the arrays and prepare them for operation. Two teams, Tanner and Piper and Burbank and MacLean, will conduct the spacewalks. During the mission, a thorough inspection will be performed in orbit of Atlantis’ heat shield as has been done on the past two shuttle flights. Atlantis’ time at the station could be extended by one or two days if needed to allow more time to complete those inspections or other operations. A second inspection of the heat shield is planned after Atlantis departs the station near the end of the flight to ensure it remains in good condition for landing. When Atlantis arrives at the station, it will mark only the second time that as many as four of the station’s five international partners have been represented onboard. STS-115 is the 116th space shuttle mission and the 19th to visit the station. Atlantis is making its 27th flight and sixth trip to the station. Atlantis’ crew begins an eight-hour sleep period at 4:15 p.m. CDT. The astronauts will awaken at 12:15 a.m. CDT Sunday to begin their first full day in orbit.