This story was updated at 6:44 a.m. EST.
The International Space Station got a bit bigger Thursday night thanks to two spacewalking astronauts who helped attach NASA's last major room for the orbiting lab and what promises to be the ultimate window on the world.
Endeavour shuttle astronauts Robert Behnken and Nicholas Patrick worked swiftly to help deliver the station's new Tranquility room and a window-lined observation dome.
At times they were nearly an hour ahead of schedule, with Behnken working so hard and fast that Mission Control asked him to slow down and top off his spacesuit's oxygen tank.
They even outpaced their crewmates inside the space station who used the outpost's robotic arm to pluck the more than 16 1/2-ton module and attached observation dome from Endeavour's payload bay, where they were packed for launch.
The spacewalkers filled their free time by taking photos and other tasks while crewmates Kathryn Hire and Terry Virts gingerly attached the new room to the left side of the station's Unity module.
"You guys are really eating it up," Endeavour commander George Zamka told the speedy spacewalkers.
While the work was going on outside the space station, astronauts inside successfully reactivated the outpost's urine recycling system. The finicky device has broken down several times in the past. Endeavour's crew delivered a new centrifuge, pump and special filter that were used to repair it.
Fast work in space
Thursday night's spacewalk began at 9:17 p.m. EST (0217 Friday GMT) and ran just over 6 1/2 hours, pushing it well into early Friday morning.
"It's a great day outdoors, nighttime right over Rio De Janeiro," said astronaut Stephen Robinson, who choreographed the spacewalk from inside Endeavour.
The spacewalking work included routing power and data cables between the Tranquility module and the space station. They also set up some equipment to be needed on a later spacewalk and removed an outdated tool platform on the station's Dextre maintenance robot.
Behnken and Patrick will tackle a plumbing job to hook up the new Tranquility room's liquid ammonia cooling hoses during their next spacewalk on Saturday. The astronauts will perform three spacewalks in all to fully activate the new module and observation dome.
Robinson told Patrick to pause in his work and take a look at Earth. The linked shuttle and space station were flying over his native England at the time.
"We're passing directly overhead," Robinson said.
"Oh wow, thanks," Patrick replied.
The new additions are NASA's last big pieces for the space station. They launched aboard Endeavour on Monday and arrived two days later when the shuttle docked at the orbiting lab.
With Tranquility, formerly known as Node 3, and the observation dome installed, the space station is more than 98 percent complete and weighs nearly 800,000 pounds (362,873 kg). The $100 billion space station is the product of 16 different countries and has been under construction since 1998.
"Let the activation of Node 3 begin," Behnken said.
Space room and windows
About the size of a small bus, Tranquility is a cylindrical module almost 24 feet (7.3 meters) long and nearly 15 feet (4.5 meters) wide.
NASA named the $382 million module after the historic Apollo 11 moon base, despite the results of an online naming contest won by TV comedian Stephen Colbert to christen it after himself.
As a consolation prize, NASA named a new treadmill COLBERT in honor of the TV funnyman. It will be located inside Tranquility along with other exercise gear, life support systems and the outpost's main robotic arm controls.
The observation dome, called the Cupola, is a seven-window observation portal with a central round pane that is 31 inches (80 cm) across, making it the largest space window ever launched into orbit. The six other windows are arranged like transparent petals around the central portal.
The Cupola is nearly 10 feet (3 meters) wide and 5 feet (1.5 meters) deep. It was launched attached to the end of Tranquility, but it will be moved to an Earth-facing port later in the mission to offer panoramic views of Earth and space to station astronauts.
Station astronaut Timothy "T.J." Creamer said Wednesday that looking at the Earth from space is one of his favorite things to do to relax. The new observation deck brought up by Endeavour's crew, he said, has been a longtime coming.
"They're bringing up the window of all windows for the space station," Creamer said late Wednesday. "And I think we all can't wait to take a gander through that."
The $27.2 million Cupola launched on the end the Tranquility module and will be moved to an Earth-facing side of the room later in the mission. Both Tranquility and the Cupola were built in Italy for NASA by the European Space Agency.
Thursday's spacewalk was the first for Patrick and the fourth for Behnken. Both men will venture outside again on Saturday night to continue their orbital construction job.
Endeavour's planned 13-day mission to the space station is one of NASA's final few shuttle flights. The space agency plans to retire its aging three-orbiter fleet in late September, once construction of the space station is complete.
Endeavour's six-astronaut crew is expected to spend eight days visiting the space station and return to Earth on Feb. 20.
SPACE.com is providing complete coverage of Endeavour's STS-130 mission to the International Space Station with Managing Editor Tariq Malik and Staff Writer Clara Moskowitz based in New York. Click here for shuttle mission updates and a link to NASA TV.