WASHINGTON, June 11 (Xinhua) -- NASA will extend the Atlantis mission for two days and add a fourth spacewalk to the mission so astronauts can repair a rip in the space shuttle's heat shield, NASA TV reported on Monday.

    The extra days will allow time to fix the inches-long tear in an insulating blanket at the back of the shuttle, said John Shannon, chair of the Mission Management Team.

    "It was 100 percent consensus that the unknowns in the engineering analysis and the potential damage ... was not acceptable and we wanted to go and fix it," he said in a briefing at Johnson Space Center.

    Late Monday, two mission specialists from the Atlantis crew completed their first spacewalk, successfully activating the new truss segment delivered to the International Space Station, the TV report said.

    James Reilly and John Olivas began their spacewalk at 4:02 p.m. EDT (2002 GMT). Their orbital stroll lasted for 6 hours and 15 minutes.

    The duo activated the new component, which was attached to the station earlier Monday.

    They made power, data and cooling connections between the station and the new segment, which contains a new set of solar arrays. They also released locks and restraints on the solar arrays and prepare its radiator and rotary joint for operation.

    The start of the spacewalk and the attachment of the segment were delayed due to the saturation of the control moment gyros that control the altitude of the station. Flight controllers performed standard procedures to bring the gyros back to normal operations.

    The truss segment activation activities will continue during the second spacewalk, slated for Wednesday afternoon.

    2 astronauts sleep in airlock, prepare for spacewalk

    BEIJING, June 11 (Xinhuanet) -- Two space shuttle Atlantis astronauts prepared for a seven-hour spacewalk Monday to install a 45-foot(14-meter) long, 35,678-pound (16,183-kg) aluminum structure that will become part of the station's exterior backbone and includes solar panels to generate more electricity.

    Crewmembers Jim Reilly and Danny Olivas were preparing for low pressure during their spacewalk by sleeping overnight in an airlock with reduced air pressure. Full story>>>

    Shuttle Atlantis docks with Space Station

    WASHINGTON, June 10 (Xinhua) -- The U.S. space shuttle Atlantis docked with the International Space Station at 3:36 p.m. EDT (1936GMT) on Sunday, ending a nearly two-day chase, according to NASA TV.

    The hatches between the two spacecraft will open at about 5 p.m., and then the two crews will greet each other and quickly begin joint operations. Full story>>>

    Atlantis crew inspect shuttle heat shield

    WASHINGTON, June 9 (Xinhua) -- The Atlantis crew spent the first full day in space inspecting the shuttle's heat shield, and they reported a 4-inch (10-centimeter) gap, according to NASA's ground control center on Saturday.

    However, NASA's shuttle managers said the gap appears not to bean urgent problem. "I don't think concern is the right word; there's no urgency with the situation," NASA's spokesman Kyle Herring was quoted as saying by AP. Full story>>>