Washington: Indian-American astronaut Sunita  Williams took over as resident flight engineer at the International Space Station and helped two fellow astronauts add a piece of metal backbone to her new home in the sky.

 
She and Joan Higginbotham, the other woman astronaut who came up on space shuttle Discovery, operated a giant robot arm to help space-walkers Bob Curbeam and Christer Fuglesang install the P5 integrated truss segment.

The two mission specialists used the robotic arm to move the new segment with only inches of clearance into its installation position. Then the space-walkers guided Higginbotham with visual cues as the exacting operation was carried out.
 

With pilot Bill Oefelein coordinating the space-walk, the job was done at 4:15 a.m. IST Wednesday, clearing the way for a critical power rewiring later this week.

The two space-walkers then started finalising the installation with power, data and heater cable connections. The excursion ended at 8.11 a.m. IST Wednesday.

Curbeam, who was on his fourth space-walk, and partner Fuglesang, a rookie flier and Sweden's first astronaut, slipped outside the station's airlock at 1.01 a.m. IST to begin six hours of work.

The two-tonne P5 spacer is the fifth truss segment added to the port side of the station. The addition of the P5 sets the stage for the relocation of the P6 truss and its set of solar arrays. The P6 will be moved from its current location on top of the Destiny laboratory to the P5 during a future mission.

 
Two more space-walks are scheduled during the six visiting astronauts' stay to reconfigure and redistribute power generated by the station's newest solar arrays. The spacewalks are set for Thursday and Saturday.

Earlier, Williams replaced European Space Agency astronaut Thomas Reiter, who will return to earth Dec 18 on Discovery along with the other six astronauts wrapping up a five-month stay on the station.

Williams will remain a member of Expedition 14 until commander Michael Lopez-Alegria and flight engineer Mikhail Tyurin are relieved by Expedition 15 in March 2007. Williams will finish the remaining time of her six-month tour of duty on the station as a member of Expedition 15 crew.

German astronaut Reiter arrived at the station in July with the STS-121 mission to give the station its first three-member crew since May 2003. He was a member of Expedition 13 until Expedition 14 began its tour of duty in September.

 
The National Aeronautics and Space Administration (NASA) and the Russian Federal Space Agency have named two astronauts and two cosmonauts for the next International Space Station crew  Expedition 15.

 
Astronauts Clayton Anderson and Daniel Tani will travel to the station next year and work as flight engineers. Cosmonauts Fyodor Yurchikhin and Oleg Kotov will spend six months aboard the orbiting laboratory.

Meanwhile, the Mission Control Centre in Houston informed Discovery commander Mark Polansky that the crew will not need to perform a focused inspection of the shuttle's heat shield Wednesday.

 
The Discovery crew will press ahead with its activities Wednesday that include retraction of a port solar array on the P6 truss segment.

NASA has been meticulous about scouting the shuttle for damage since losing Columbia and seven astronauts, including India-born Kalpana Chawla, in 2003 because of a debris strike.

"That's outstanding news," said Polansky. "We're happy to hear that we can go on with normal (station) assembly tomorrow."

If the array fails to fold up automatically, NASA might dispatch Discovery's space-walkers on an extra outing to manually retract the panel. It must be retracted at least 40 percent to leave room for the new arrays to rotate as they track the sun for power.

 
"Hopefully, that will work according to plan," Polansky said.