HOUSTON, July 30: Two shuttle Discovery astronauts completed a seven-hour spacewalk on Saturday to restore a critical steering device on the International Space Station and test shuttle heat shield repairs that Nasa hopes will prevent another Columbia disaster.

“What a view,” Japan’s Soichi Noguchi said as he drifted out of Discovery’s airlock into the open payload bay and looked down on Southeast Asia 224 miles (358 km) below. The spacewalk was Nasa’s first at the International Space Station since Nov 2002.

After taking a few minutes to acclimatize to the vastness of open space, Noguchi and Robinson, both first time spacewalkers, used a specially designed caulking gun and putty knives to try to repair sample shuttle heat shield tiles and wing panels that had been purposefully damaged.

The astronauts worked only on the sample materials in the payload bay and did not touch any of the minor damage caused during liftoff to Discovery’s heat shield, which is believed to be in good shape for landing.

Nasa lost shuttle Columbia and its seven astronauts during the last landing attempt on Feb. 1, 2003. The ship’s wing had been damaged during launch by falling debris and as the shuttle sailed through the atmosphere for landing, hot gases blasted inside the hole, tearing the ship apart as it flew over Texas.—Reuters