Astronauts David Wolf and Piers Sellers spent seven hours in the vacuum of space hooking up cables, setting up a video camera and opening latches on a truss radiator panel. Problems with stuck bolts and the station's robot arm added some tense moments during the spacewalk, which ran about a half-hour longer than expected.
"It didn't quite go as planned, but the whole team really came together to pull it off," Wolf radioed to ground controllers as he and Sellers returned to the station's airlock. "It was fun working with you," he added.
"We got everything done," flight director Milt Heflin said during a news conference after the spacewalk. "We had to do it a little bit differently than we planned ... but we're in pretty good shape."
The day began early with shuttle flight engineer Sandra Magnus and space station science officer Peggy Whitson using the station's crane delicately to pluck the 14-ton truss from Atlantis' cargo bay and deftly position it to the end of the cornerstone beam located on top of the Destiny science laboratory.
As soon as the new segment, called S1 -- for starboard or right-side -- was automatically bolted into place, Wolf and Sellers left the airlock with a long to-do list to prepare the new beam for service. They attached two sets of electrical cables between the S1 and the first segment, called S0, then hooked up fiber optic and data cables for video and communications.
Other tasks included unlatching a rail cart that will be used during future spacewalks to haul equipment to various work sites and setting up an S-band communications antenna.
The spacewalk was the second for Wolf, who served aboard the Russian Mir space station, and the first for Sellers, who was stunned by his initial view of Earth from outside a spaceship.
"David, I don't know how to tell you this, but they've made the pool bigger," joked Sellers, referring to the pool the men used for training. "I'm looking straight down. It's a beautiful view of the shuttle and the ground. This is unbelievable."
The crews plan to take some time off Friday to prepare for a second spacewalk on Saturday. Atlantis reached the space station on Wednesday for a week-long mission.