BEIJING, June 12 (Xinhuanet) -- NASA managers decided Monday to extend space shuttle Atlantis' mission from 11 to 13 days to attempt to fix a thermal blanked that peeled back during launch.

    A decision has not been made whether to repair the 4-by-6-inch area over a pod for the engines during a previously planned spacewalk or to add an extra one, managers said.

    Although 11 previous shuttle flights have had blanket or tile damage in that area of the spacecraft without any problems, managers were told by engineers, "'We think we're going to have some damage ... if you don't go off and fix this,'" said John Shannon, chairman of the mission management team.

    Engineers think the blanket came loose because of aerodynamic forces during launch, not by being hit by a piece of debris during liftoff. The rest of the vehicle appeared to be in fine shape, NASA said.

    Engineers didn't think the intense heat when the shuttle re-enters Earth's atmosphere could burn through the graphite structure underneath the blanket and jeopardize the spacecraft or the lives of astronauts, but they are concerned it might cause some damage that would require repairs on the ground.

    With three additional shuttle flights to the space station planned this year, NASA can't afford any delays. During the repair, an astronaut will probably reach the blanket, located near Atlantis' tail, by attaching himself to the end of the shuttle's robotic arm and boom.

    While mission managers debated fixing the thermal blanket, two astronauts floated outside the international space station Monday to begin connecting the orbiting outpost's newest addition: a 35,000-pound segment that will increase its power capability.

    The start of the spacewalk was delayed by more than an hour because the four spinning gyroscopes that keep the space station properly positioned became overloaded. Space shuttle Atlantis was used to help control the station's orientation until the gyroscopes were able to take over again.

    (Agencies)