U.S. astronauts from the space shuttle Endeavour are examining damage to the shuttle's heat shield.
The crew is using a camera and laser on a robotic arm to check out the heat shield, which NASA officials say was likely hit by a piece of ice during launch Wednesday.
Engineers back on Earth have been analyzing photographs of a gouge or scratch on the underside of the shuttle, measuring about seven and one-half centimeters square (7.5cm x 7.5cm).
Results of Sunday examination by the astronauts could help determine the extent of the damage, and whether it poses any risk when the shuttle returns to Earth later this month.
Based on the crew's findings, engineers will decide whether the heat-shield damage is significant enough to warrant repairs in orbit.
The shield is made up of more than 20 thousand small heat-resistant tiles covering the shuttle's hull. The tiles protect the spacecraft from searing heat when it re-enters the atmosphere.
In February of 2003, a damaged heat shield caused the fiery breakup of the shuttle Columbia. All seven astronauts aboard the craft died as it disintegrated in the upper reaches of Earth's atmosphere.
Some information for this report provided by AP.