Shuttle dilemma has NASA scrambling

SPACE CENTER, Houston -- A couple of short strips of filler material dangling from Discovery's belly had NASA scrambling Sunday to determine whether the protrusions might endanger the space shuttle during re-entry and whether the astronauts might need to attempt a repair.\nThe potential trouble has nothing to do with launch debris -- for a change -- but rather material used to fill the spaces between thermal tiles, a common problem in the past although not necessarily to this extent.\nFlight director Paul Hill said engineers will spend the next day analyzing the situation and decide Monday whether to have the crew's two spacewalkers cut, pull out or shove back in the hanging material.\nIt could be that it's perfectly safe for Discovery and its crew of seven to fly back with the two drooping pieces, Hill stressed, as shuttles have done on many previous flights.\nOne is sticking out an inch between thermal tiles, the other six-tenths of an inch. The longest protruding gap filler seen on a returning shuttle before was a quarter-inch, but Hill cautioned that measurement was taken following re-entry, and the intense heat could have burned some of it off. The extremely thin gap fillers are made of a felt-like material and ceramic, and are held in place with glue and by the tight fit.\nAny repair, if deemed necessary, could be performed during the third spacewalk of the mission, now set for Wednesday or a fourth unplanned spacewalk might be required, Hill said. The astronaut would have to stand on a long robotic arm in order to reach the two areas, located on the shuttle's belly near the nose.\nOne extreme option under consideration is to put an astronaut on the end of the brand new 100-foot inspection crane, but it could be a bouncy ride and that makes lots of experts "understandably nervous," Hill said.\nHe said there are strong arguments for and against most of the options.\nAnything dangling from the bottom of the shuttle during re-entry will overheat the area, as well as downstream locations. The ongoing analysis is to decide whether that overheating will be within safety limits.\nA hole in Columbia's left wing, left there by a large chunk of flyaway fuel-tank foam, led to the spacecraft's destruction during re-entry on Feb. 1, 2003. All seven astronauts were killed.\nNASA has cleared all of Discovery's thermal tiles for landing on Aug. 8. The only remaining issues, before the final go-ahead can be given for descent, are the reinforced carbon panels that line the wings and nose cap, and the two hanging gap fillers.