The solar arrays on the newly delivered 17.5 ton truss segment were fully unfolded at 7:44 a.m. CDT.
The power generated by the arrays will not be used by the station until another shuttle flight in December. During that mission, STS-116, astronauts will rewire the complex and activate a cooling system. The arrays currently are powering their own system, including batteries and other electronics equipment.
The solar panels have a wingspan of 240 feet attached on the port side of the station. They can generate 66 kilowatts of power.
Flight controllers commanded the arrays to begin unfolding at 4 a.m. CDT. They were originally to begin unfolding Wednesday night. A software glitch during checkout of the Solar Alpha Rotary Joint (SARJ), which will rotate the wings, delayed the deployment.
Unfurled one at a time, the wings were deployed halfway before being fully unfolded. During the unfurling, Atlantis' astronauts noted that some of the panels stuck. The phenomenon, called "stiction," also occurred when the station's first set of solar panels was deployed during a shuttle mission in late 2000.
The crew also maneuvered the Canadarm2 robotic arm in a "double walk off,” moving it from the Mobile Base System to the Destiny Lab in an inchworm-like procedure.
Tomorrow, mission specialists Joe Tanner and Heide Stefanyshyn-Piper will conduct the third and final spacewalk of the mission to release restraints on the cooling radiator of the new truss section. The radiator will be unfolded later. They also will install an external wireless TV transmission antenna to improve TV transmission from cameras mounted on spacesuit helmets. Tanner and Piper expect to have time to remove a materials science experiment from the hull of the Quest airlock to return to Earth.