Astronauts Steven Smith and Rex Walheim began repressurizing the space station's Quest airlock module at 4:15 p.m. to officially end a six-hour 27-minute spacewalk, the third of four planned for the shuttle Atlantis' crew.

During today's excursion, the astronauts rewired the station's robot arm, enabling it to draw power from the new S0 truss, and removed launch locks from a mobile transporter on the front face of the truss. The $190 million transporter, which eventually will be used to move the robot arm to different work sites on the truss, will be tested Monday when ground controllers command it to creep back and forth along S0.

A few minutes before 2 p.m., the astronauts took a moment to marvel at the view from 240 miles up.

"Is that the blue tongue of the Bahamas and Florida?," Smith asked.

"That would be it," someone replied.

"Look at that!" Smith exclaimed.

"Cuba down there below us."

"Yep. See that dark blue part, Rex, that kind of invades the rest of that green area?"

"Oh that's beautiful!" Walheim exclaimed. "Look at that! That's incredible." "Yep. Boy, what a pass."

The spacewalk was relatively trouble free and the astronauts managed to stay on schedule most of the day. But work on the ground to check out the re-wired robot arm took a bit longer than expected. As a result, Smith and Walheim were told to skip a final planned task to install a so-called airlock "spur" to help future assembly crews make their way up to the truss. The spur will be installed during the current mission's final spacewalk Tuesday.

In the meantime, ground engineers report the arm is operating flawlessly, drawing power from the truss and utilizing a new video distribution system allowing operators inside the station to see three TV views from the arm at the same time.

This was the 37th spacewalk devoted to space station assembly. With its conclusion, 30 NASA astronauts, one Canadian and five Russian cosmonauts have logged 229 hours and 50 minutes building the international outpost. Of that total, 12 spacewalks totaling 62 hours and 35 minutes were staged from the international space station, including 36 hours and 48 minutes by on-board expedition crews.