The U.S. space agency NASA says it has discovered no serious defects in the shuttle Discovery's surface as the result of debris impacts during Tuesday's launch. Mission managers have also extended Discovery's visit to the International Space Station for extra supply transfers. They made the decision because they had earlier suspended future shuttle missions until NASA learns how to prevent further debris strikes like the kind that doomed the shuttle Columbia mission in 2003.
NASA says an assessment of the images from Discovery shows that damage to its thermal coverings is unlikely to make the orbiter vulnerable to the searing re-entry heat that caused Columbia's disintegration.
Columbia's wing was punctured by a piece of hard insulation foam that fell from its external fuel tank during liftoff. When several large pieces of foam shed during Discovery's takeoff, NASA grounded flights again until it can prevent a recurrence.
Deputy shuttle program manager Wayne Hale says the foam presumably caused the damage seen in the fragile ceramic tiles that protect Discovery's underside, but the damage is minor. Furthermore, he says loose thermal farbric on the top of the orbiter is no threat, either.
"The tile and the blankets [farbric] have been formally cleared by the engineering team, a few pock-marked tiles, a little gouge at the base of the nose landing gear door, a thermal blanket that had billowed out on the side below the commander's window," he said. "All of those item have been formally assessed through rigorous engineering models in great detail and found to be acceptable to fly home as is."
Mr. Hale says he also expects technicians to clear the reinforced carbon panels that protect the shuttle wings' front edges.
The new shuttle flight moratorium has led NASA to extend Discovery's mission to the space station for an extra day, until next Saturday, so the combined crews can transfer more supplies than originally planned for this mission. The extra material includes water, laptop computers, and office equipment, all from the shuttle's own stores.
Station official Bill Gerstenmeier says NASA will continue to rely on Russian rockets to meet the outpost's supply needs, as it has since the Columbia disaster.
"We're in very good shape," he said. "We had been planning a contingency that if we didn't get any shuttle flights this year, we were fine through the end of the year essentially doing what we have been doing for the past two years. So we're going to be in great shape for the remainder of the year."
A spacewalk by two shuttle astronauts Saturday further bolstered the station by restoring power to a dysfunctional gyroscope, one of four used to stabilze the space laboratory's position. On another spacewalk Monday, they will replace a second failed gyroscope with a new one brought up on the Discovery, ensuring adequate backup.
The two spacewalkers also successfully tested new methods to repair damaged shuttle tiles with thick, gummy, caulk-like material on deliberately damaged tile samples. NASA wants to determine if astronauts can make emergency surface patches in orbit to prevent another disaster like that which befell Columbia.
