WASHINGTON, Aug 11: The National Aeronautics and Space Administration (Nasa) on Saturday attempted to gauge the extent of ice damage on the space shuttle Endeavour’s heat shield as two astronauts installed a new beam to the international space station.

Mission specialists Rick Mastracchio of the United States and Canadian Dave Williams headed outside the International Space Station to install and activate a new truss, the first of three planned spacewalks of the mission, to which a fourth could be added to repair the damage.

Meanwhile, Nasa experts on Earth were analysing pictures taken of the shuttle during a routine inspection on Friday after it docked with the station, that showed the apparent three square-inch gouge on the shuttle’s heat shield.—AFP/AP