Washington - Two astronauts successfully completed a nearly seven-hour spacewalk Wednesday after removing an empty ammonia tank from the International Space Station, the US space agency said. Danny Olivas and Nicole Stott completed the first of three planned spacewalks of their mission, the National Aeronautics and Space Administration (NASA) said.
The 816-kilogramme empty ammonia tank was the largest item ever moved by astronauts during a spacewalk. It is used to remove heat from the station. A new ammonia tank is to be installed by Olivas and Swedish astronaut Christer Fuglesang in the second spacewalk on Thursday.
Shuttle commander Rick Sturckow and Pat Forrester guided the spacewalkers through the procedures while pilot Kevin Ford and flight engineer Bob Thirsk operated the station's robotic arm, NASA said.
The astronauts also retrieved experiments that had been stored outside the station.
The spacewalk took place after the space shuttle Discovery docked Sunday at the space station. On Tuesday, the crews of the shuttle and space station transferred new cargo to make the station more comfortable for the expanded crew.
The Colbert treadmill, named for US comedian Stephen Colbert, was among the items brought on board, along with a new crew sleeping quarters and an air-filtration system.
Colbert, who plays a pompous news commentator on his cable television programme, had organized fans to vote for him in a NASA competition to name a module on the International Space Station. Their dedication paid off when the comedian's name came first in the US space agency's online poll, besting all of NASA's suggested names.
NASA was caught off guard with the naming campaign and dragged its feet, saying it did not typically name space station hardware after living people. Instead, it chose the name Tranquility, after the moon's Sea of Tranquility, where the Apollo 11 mission touched down.
As a compensatory gesture, and in the spirit of the comedian, NASA named a new treadmill in Colbert's honour, even concocting an acronym for the exercise device - the Combined Operational Load Bearing External Resistance Treadmill.
The planned 13-day mission is designed to transport new equipment and experiments to the space station to boost its capacity as an orbiting laboratory.
Stott is also replaced astronaut Timothy Kopra aboard the station.
