ISS Construction: Spacewalkers Add New Piece to Space Station
One of two STS-116 spacewalkers can be seen here during a Dec. 12, 2006 outing to install a new Port 5 truss to the International Space Station (ISS).
Credit: NASA TV.

HOUSTON -- The International Space Station (ISS) grew a bit larger Tuesday after two spacewalking astronauts helped install a new piece of the orbital laboratory's metallic backbone.

Discovery astronauts Robert Curbeam and Christer Fuglesang, aided by their robotic arm wielding crewmates, successfully attached the two-ton Port 5 (P5) spacer segment to the portside end of the outpost's main truss during a six-hour, 36-minute spacewalk.

"That is beautiful," Curbeam said as the P5 spacer moved into place.

Tuesday's spacewalk began at 3:31 p.m. EST (2031 GMT) with Beamer and Fuglesang stepping out of the space station's Quest airlock as the outpost and their docked shuttle Discovery passed 220 miles (354 kilometers) over central Europe.

"It feels good, let me tell you," Curbeam said just after stepping into space to start the fourth spacewalk of his astronaut career.

Fuglesang, a European Space Agency astronaut and Sweden's first spaceflyer, made his first spacewalk during the extravehicular activity (EVA). To mark the event, flight controllers awoke Discovery's crew Tuesday morning with the Swedish band Abba's song 'Waterloo' chosen for Fuglesang.

Inside the space station, Curbeam's fellow STS-116 mission specialists Joan Higginbotham and Sunita Williams, now an ISS crewmember, wielded the ISS robotic arm to maneuver the $11 million P5 truss into position. Discovery pilot William Oefelein choreographed the spacewalk from the shuttle's flight deck.

About the only hitch was a lost extension for Fuglesang's pistol grip tool, which apparently slipped free of its mooring on his spacesuit work bench.

"I was looking around, I didn't see it," Fuglesang told flight controllers. "But, of course, it's dark here."

STS-116 commander Mark Polansky replayed video from Fuglesang's spacesuit helmet camera after the spacewalk to help flight controllers try to track the lost tool.

During the spacewalk, mission controllers told Polansky that a focused inspection of Discovery's heat shield will not be required Wednesday to help engineers determine the spacecraft's health.

"Well, that's outstanding," Polansky said.

Space station grows

The P5 truss adds another 4,110-pound (1,864-kilogram) to the more than 200-ton space station and sets the stage for the future relocation of the Port 6 truss.

Maneuvering P5 into position at the end of the Port 3/Port 4 (P3/P4) truss segment appeared to be tricky but flawless, with Curbeam and Fugelsang giving verbal updates of where Higginbotham and Williams should move the new space station piece. At times the truss segment was within inches of a sensitive electronics box.

"You're eyes are calibrated like nobody else's, Beamer," Higginbotham told Curbeam.

The P5 segment will serve as a structural bridge between two massive trusses whose solar arrays make up part of the space station's power plant. Without the new P5 element, the older array-laden Port 6 truss atop the ISS would be unable to move to its permanent berth on the station's port side near two newer solar wings on the P3/P4 segment.

P5's successful installation prompted some celebration aboard the ISS.

"We didn't want to scream on the loop," Higginbotham said, referring to the communications channel used in today's spacewalk. "But we're very happy."

Curbeam and Fuglesang even managed to perform a series of extra P5-related jobs, included wiring up several utility connections and releasing launch locks on the truss' empty end to prepare for the future arrival of the P6 solar arrays.

Other tasks

Among the other chores on Curbeam and Fuglesang's orbital to-do list were the relocation of a robotic arm grapple fixture, as well as the repair of a video camera at the opposite end of the space station's main truss.

The grapple fixture's move required a bit of extra elbow grease so that Fuglesang could remove some hard-to reach-bolts.

Curbeam also had some trouble removing the faulty camera, which had to be pointing straight upward to unlatch its locks.

"Wiggling it is not working," Curbeam told flight controllers.

"Ok, no go on the wiggle," they replied.

 After some troubleshooting, Curbeam and Fuglesang successfully installed the camera, completing their primary spacewalk goals.

Tuesday's spacewalk marked the 46th spacewalk based from the ISS and the 84th dedicated to station assembly and maintenance, NASA officials said. It is the first of three planned EVAs for the STS-116 mission.

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