NASA said the mission of the space shuttle Atlantis will be extended by two days so astronauts can repair a damaged cloth heat shield over one of the spacecraft's engine pods.
The space agency decided Monday to lengthen Atlantis' stay in orbit at the International Space Station to 13 days. The extra time will allow the crew to perform an additional spacewalk to fix the damage near the shuttle's tail that peeled back during Friday's launch.
Engineers didn't think the intense heat generated by re-entry could burn through the graphite structure underneath the blanket and jeopardize the spacecraft or the lives of astronauts. But they worried 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 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.
John Shannon, chairman of the mission management team said an engineering analysis had produced "a 100 percent consensus" that the damage "was unacceptable and we should go in and fix it if we could."
The 4-by-6 inch damaged area over an engine pod would be repaired during a previously planned third spacewalk or a fourth one if necessary, NASA officials said. The area where the repair will be made reaches 1,000 degrees during re-entry.
"We think that if ... we can secure it somehow, we don't have to worry about that blanket anymore," Shannon said.
Mission Control on Tuesday planned to begin remotely unfolding a pair of solar arrays, which two astronauts helped install on the international space station during a spacewalk Monday.
Astronauts James Reilly and Danny Olivas removed locks and restraints on the new truss segment, which was attached earlier Monday to the station's girder-like backbone.
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.
Starting overnight, the 300-foot pair of arrays was to be deployed from its storage box on the new segment slowly, in stages, to get the panels warmed by the sun and prevent them from sticking together.
From NPR reports and The Associated Press