Space Shuttle Endeavour gouge runs deep

CAPE CANAVERAL, Fla. -- A close-up laser inspection by Endeavour's astronauts yesterday revealed that a 9-cm-long gouge penetrates all the way through thermal tiles on the shuttle's belly, and had NASA urgently calculating whether risky spacewalk repairs are needed.

A chunk of insulating foam smacked the shuttle at liftoff last week after it ricocheted off the fuel tank, carving out the gouge.

The unevenly shaped gouge -- which straddles two side-by-side tiles and the corner of a third -- is 9 cm long and 5 cm wide. Yesterday's inspection showed that the damage went all the way through the 2.5-cm-thick tiles, exposing the felt material sandwiched between the tiles and the shuttle's aluminum frame.

Mission managers expect to decide today, or tomorrow at the latest, whether to send astronauts out to patch the gouge. Canadian astronaut Dave Williams and fellow astronaut Rick Mastracchio are likely to be the ones to conduct the necessary patchwork on the shuttle's belly.

Engineers are trying to determine whether the marred area can withstand the searing heat of atmospheric re-entry at flight's end, and actual heating tests will be conducted on similarly damaged samples.

This area is subjected to as much as 1,260C during re-entry. A hole, if large and deep enough, could lead to another Columbia-type disaster.

FOAM BROKE FREE

Teacher-astronaut Barbara Morgan conducted the slow and painstaking survey, along with crewmate Tracy Caldwell. They used the 30-metre robotic arm and extension boom that flew up on Endeavour, steering the instrument to a spot just above the gouge and keeping it hovered there.

Laser sensors and cameras zoomed in on the damage, white and easily visible against the black tiles, from a variety of views.

Four other damaged areas also were scanned. Engineers believe the piece of foam struck the shuttle's underside, creating the big gouge, then skimmed along the bottom and nicked it in at least three spots.

The foam came off a bracket on the external fuel tank 58 seconds after Wednesday's launch, fell down onto a strut on the tank, then bounced up, right into Endeavour's belly.

Ice apparently formed near the bracket, which helps hold the long fuel feed line to the tank, and caused the foam to pop off when subjected to the vibrations of launch, said John Shannon, chairman of the mission management team. The debris that came off is believed to have been grapefruit-sized.

Endeavour has been docked at the space station since Friday. It will remain there until Aug. 20 for a record 10-day stay, three more days than initially planned. Mission managers yesterday approved the prolonged visit based on the successful testing of a new power transfer system flying on Endeavour. The system is drawing power from the station and converting it for use aboard the shuttle.