Two shuttle Discovery astronauts completed a seven-hour spacewalk on Saturday to restore a steering device on the International Space Station and test 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 South East Asia 358 km below.‘‘Yeah, it’s been a long road,’’ said spacewalking partner and US astronaut Steve Robinson.The spacewalk was NASA’s first since November 2002.After taking a few minutes to acclimatise 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, purposefully damaged heat shield tiles and wing panels.The astronauts worked only on the sample materials and not on the minor damage caused during liftoff to Discovery’s heat shield, which is believed to be in good shape for landing.Robinson got to work first, squeezing out thick black beads of a heat-resistant product called Noax, then working the material into cracks in the sample wing panel. ‘‘It’s about like pizza dough,’’ he said.Noguchi then used another device similar to a shoe polish applicator to dab a material, known as an emittance wash, on damaged heat-shield tile samples.Engineers will study the repaired sample tiles and wing panels after the shuttle’s return.Noguchi replaced a broken Global Positioning System antenna on the space station, and the spacewalkers also swapped a power cable to fix a backup gyroscope which had failed in March. The gyroscope is one of four that keep the station properly positioned without using the station’s limited supply of fuel for rocket thrusters.After sailing through all their tasks, the astronauts photographed some areas of damage on the shuttle that engineers want more information about while crew members in the shuttle carried out an additional unscheduled scan of Discovery’s left wing with a special boom.—Reuters‘Planet’ found beyond Pluto Los Angeles: California Institute of Technology astronomers have discovered what they believe is the tenth and most distant planet in our solar system, a ball of rock that is about twice as big as Pluto and about three times as far away. The new object, temporarily called 2003 UB313, is currently at its farthest distance from the sun, about 97 times the distance between the sun and Earth. The surface of the new object is very similar to that of Pluto, a mixture of about 70 per cent rock and 30 per cent water ice. It is very cold, probably about minus 400 degrees Fahrenheit. —LAT/WP
