CAPE CANAVERAL, Florida—NASA managers on Wednesday cleared the shuttle Atlantis for launch on February 7 to deliver Europe's first permanent space laboratory to the International Space Station.
The only issue pending is a bent coolant hose discovered in the shuttle on Tuesday. But program manager Wayne Hale said Atlantis should be OK to fly as is.
Engineers are studying a similarly bent pipe removed from the shuttle Discovery to determine if there are any safety concerns. The pipe is part of the cooling system used by the shuttle in orbit.
"If it's not safe to fly, we won't fly," Hale told reporters at a news conference.
Earlier on Wednesday, two U.S. astronauts aboard the space station replaced a broken motor on one of its solar wings during a seven-hour spacewalk, clearing the way for more modules to be added to the outpost.
"Thanks for making it look so easy," astronaut Tom Marshburn from NASA's Mission Control Center in Houston radioed to the crew as they returned to the station's airlock after the outing.
It was the fifth spacewalk that station commander Peggy Whitson, a 47-year-old biochemist, has made since arriving at the outpost in October, and the fourth for flight engineer Dan Tani, 46, who arrived two weeks after Whitson during the last shuttle mission.
Bus-sized Module
Tani had been due to go home in December aboard Atlantis, but the flight was postponed because of problems with a fuel sensor system. The faulty equipment was replaced, clearing the way for the February 7 liftoff.
The shuttle will carry Europe's first permanent space station laboratory, a bus-sized module named Columbus, which is to be connected to the seven-room complex. NASA plans to follow Columbus' launch with one carrying the first part of Japan's Kibo laboratory complex in March.
Before the Japanese components can be installed, NASA needed to recover at least part of the station's troubled solar power system. One side of the station's two solar power wings has been locked in place since December, producing a fraction of the power needed to support expanded station operations.
Whitson and Tani replaced a 200-pound (90-kg) motor that allowed the wing to pivot its panels to catch the sun's rays.
A more complicated repair that will allow the wing to freely rotate like a Ferris wheel is in the planning stages, said Kirk Shireman, NASA's deputy space station program manager.
Whitson and Tani left the station's airlock shortly before 5 a.m. EST (1000 GMT). While installing the motor, they worked only during night-time passes around Earth, when the solar energy-collecting cells are passive, to avoid electrical shock.
The station circles Earth about every 90 minutes, half the time in darkness and half in daylight.
NASA has completed about 60 percent of the work on the $100 billion station. It has until September 30, 2010, to finish 12 remaining construction and resupply flights before the shuttle fleet is retired.
The agency also plans to make a final servicing call to the Hubble Space Telescope.
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