Live in Orbit: Astronauts Cap Truss Construction

Discovery's astronauts mounted a 15.5-ton girder to the starboard end of the International Space Station's central truss, capping a decade-long effort to assemble the metallic backbone of the outpost.

Japanese astronaut Koichi Wakata deftly maneuvered the 31,060-pound truss segment to a point 4.9 feet from the starboard end of the truss.

Then, with spacewalkers Steve Swanson and Ricky Arnold watching on, mission specialist John Phillips gently eased the $300 million segment into a claw that clamped down on a mating attachment, mechanically connecting the new girder to the rest of the central truss.

Wielding a high-tech ratchet wrench, Arnold then engaged a capture latch that linked the new segment with the starboard end of the truss.

"Ricky that was a fantastic job," mission specialist Joe Acaba said from inside the joined shuttle-station complex. "Excellent work everyone."

The spacewalkers now are tightening bolts that secure the segment to the central truss and attaching grounding straps between the S5 and S6 segments.

That work will enable them to begin hooking up the four connections that allow power and data to pass through the central truss to station systems.