CAPE CANAVERAL, Fla. - NASA on Friday discovered a worrisome gouge on Endeavour's belly soon after the shuttle docked with the international space station.
It was possibly caused by ice that broke off the fuel tank a minute after liftoff.
The gouge is about 3 inches square. It was spotted in zoom-in photography taken by the space station crew shortly before Endeavour delivered teacher-astronaut Barbara Morgan and her six crewmates to the orbiting outpost.
The chairman of the mission management team says if the gouge is deep enough, the shuttle astronauts may have to patch it during a spacewalk.
On Sunday, the astronauts will inspect the area, using Endeavour's 100-foot robot arm and extension beam. Lasers on the end of the beam will gauge the exact size and depth of the gouge and then engineering analyses will determine whether the damage is severe enough to warrant repairs.
The gouge is several feet from the starboard main landing gear door. It appears to be the result of ice, although engineers are not positive. The damage could have been caused by a piece of foam insulation that came off the external fuel tank.
Radar images show a white spray or streak coming off Endeavour 58 seconds after liftoff. Engineers theorize that if the debris was ice, it pierced the tile and then broke up, scraping the area downwind.
Even though it was an extremely hot day in Florida, the fuel tank was loaded with super-cold fuel, which could have allowed dangerously big chunks of ice to form on its surface.
It is uncertain how big the debris was. A 1.67-pound chunk of foam led to Columbia's catastrophic re-entry in 2003.