Porch installed on station

Spacewalking astronauts secured a 'front porch' on Saturday to the International Space Station that will expose scientific experiments to the cold vacuum of outer space. -- PHOTO: REUTERS

HOUSTON - SPACEWALKING astronauts secured a 'front porch' on Saturday to the International Space Station that will expose scientific experiments to the cold vacuum of outer space.

Lead spacewalker David Wolf and rookie astronaut Timothy Kopra spent about 5 1/2 hours outside the station preparing the Japanese-built platform to be attached to the front of the station's US$2.4 billion ( S$3.5 billion) Kibo laboratory, Japanese for 'hope.' Then, using the station's robotic arm, astronauts gingerly drove the four-tonne platform to 'hard dock' with the Kibo lab at 7.29pm EDT (2329 GMT).

'It really worked like a champ,' said Mr Mark Polansky, commander of the shuttle Endeavour, which arrived at the station on Friday for an 11-day mission.

The platform is designed to hold 10 experimental payloads that need to be exposed to the open environment of space.

In four additional spacewalks scheduled for the mission, astronauts will work on an equipment cart and prepare a docking port for Japan's new cargo ship, which is scheduled to make its debut flight later this year. The next spacewalk is scheduled on Monday.

Nasa also completed its initial analysis of Endeavour's heat shield on Saturday and determined no additional inspections would be needed by the shuttle crew.

The agency is trying to figure out why Endeavour lost so much insulating foam from its external fuel tank during the climb to orbit on Wednesday.

Nasa has been concerned about flyaway foam since losing shuttle Columbia in 2003. Columbia was hit by a piece of falling foam during launch. The impact broke a panel on one of its wings, allowing hot gases to blast inside the structure as the shuttle flew through the atmosphere for landing 16 days later. All seven astronauts aboard died in the accident.

Any debris impacts on Endeavour were minor, but Nasa has said it will not clear any more shuttles for launch until it is sure future tanks will not shed foam like Endeavour's. Nasa said on Saturday it expected the work would delay launch of its next flight from Aug 18 to later in the month.

The US space agency has seven missions remaining after Endeavour's to complete construction of the US$100 billion space station, a project of 16 nations, and then retire the shuttle fleet. -- REUTERS