Mission Specialists Joe Tanner and Heidemarie Stefanyshyn-Piper wrapped up STS-115's first spacewalk at 11:43 a.m. EDT. Their efforts centered on preparing the P3/P4 truss for operation. The new truss was installed this morning before the start of the spacewalk. Today's construction efforts marked the resumption of the on-orbit construction of the space station.

The spacewalking duo began the excursion at 6:17 a.m., and cruised through the timeline. They installed power and data cables between the P1 and P3/P4 structures in preparation for solar array deployment. They also released launch restraints on the Solar Array Blanket Box and performed other tasks to configure the structure for upcoming activities. They moved through the spacewalk so quickly flight controllers in the Mission Control Center in Houston gave them permission to complete tasks scheduled for future spacewalks.

The new truss element, which includes a set of new solar arrays, was attached to the station at 3:48 a.m. EDT. Tanner and Piper began their excursion after bolts connecting the P3/P4 to the P1 truss were tightly secured. The third of four bolts was tightened at 4:35 a.m., officially making the P3/P4 a part of the station.

The new 17.5-ton, 45-foot truss will provide power, data and communication services for the station. The arrays will be unfurled to a full length of 240 feet Thursday and will eventually double the station's power capabilities.

During the early stages of the spacewalk, the Mission Control Center in Houston told the STS-115 crew that no focused inspections of Space Shuttle Atlantis' heat shield were needed. The good news allows the crew to press ahead as planned with the mission's second spacewalk Wednesday.

Mission Specialist Dan Burbank coordinated the spacewalk activities. Mission Specialist Steve MacLean and Expedition 13 Flight Engineer Jeff Williams operated the station's robotic arm, which was used to install the P3/P4.

The astronauts will quickly begin preparations for the mission's second spacewalk, scheduled for 5:15 a.m. EDT Wednesday. Burbank and MacLean will conduct the spacewalk and will begin preparations with "camp out" in the Quest Airlock at 2:40 p.m. today.