Shuttle on alert

CAPE CANAVERAL, FLA. -- NASA discovered a worrisome gouge on Endeavour's belly soon after the shuttle docked with the International Space Station yesterday, possibly caused by ice that broke off the fuel tank a minute after liftoff.

The gouge -- about 19 cm square -- was spotted in zoom-in photography taken by the space station crew shortly before Endeavour delivered its seven crew members to the orbiting outpost.

"What does this mean? I don't know at this point," said John Shannon, chairman of the mission management team. If the gouge is deep enough, the shuttle astronauts may have to patch it during a spacewalk, he said.

Tomorrow, the astronauts will inspect the area, using Endeavour's 30-metre robot arm and extension beam. Lasers on the end of the beam will gauge the exact size and depth of the gouge, Shannon said, and then engineering analyses will determine whether the damage is severe enough to warrant repairs.

DOWNWIND SCRAPES

The gouge, which appears white against the black tiles on the underside of Endeavour, is several metres 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.

Shannon said it is uncertain how big the debris was. A 750-gram chunk of foam led to Columbia's catastrophic re-entry in 2003.

Ice is heavier than foam, however, and would cause more damage.

In all, nine pieces of debris, mostly foam, came off the fuel tank during Wednesday evening's liftoff, and three were believed to have struck the shuttle.

Mission Control quickly notified the seven shuttle astronauts, including Canadian Dave Williams, of the damage.

Cmdr. Scott Kelly was at the controls when Endeavour performed the orbital backflip earlier in the day so the space station crew could photograph the belly and check for any damage.

Shortly afterward, Endeavour pulled up to the space station and neatly parked as the two spacecraft soared above the South Pacific.

After checking for leaks, hatches between the shuttle and station were pushed aside and one by one the Endeavour astronauts floated aboard.

Once on board the station, the shuttle crew began preparing for the mission's first spacewalk today when the new piece of the station's truss will be locked into place.