Two errant strips of heavy insulating cloth, each protruding by about 3cm, have set off debate within NASA over whether they may cause hazardous overheating as the shuttle Discovery returns to Earth. If so, the agency may order the first spacewalk to the underside of the orbiter to correct the problem, officials said on Sunday.
Analysts are still studying whether these strips of material, called gap filler, poking out of the shuttle's underbelly by about 3cm, could lead to unusual patterns of heating during re-entry. If they are poking out at the forward end of the shuttle, as both of these are, the heating could affect parts of the craft's belly downstream, with some areas becoming as much as 25 percent hotter and beginning the most severe heating earlier than usual. That could potentially be a threat to its structure.
The evaluation of the problem has provoked "strong disagreement" among NASA analysts about whether it poses a safety hazard, said Paul Hill, the mission's lead flight director. Some engineers are very concerned about the situation, he said, while others believe "this is not a big deal."
Mission managers expected to have enough data and aerodynamic analysis about the gap fillers to reach a conclusion by yesterday, Hill said. If a spacewalk is ordered, astronauts will try to pluck the tough material the rest of the way out, push it back into place or cut it off with a hacksaw.
Removing the protruding material, called gap filler, could be as simple as grabbing it between the thumb and forefinger and pulling it free, said N. Wayne Hale, the shuttle program's deputy manager.
If the job can be done with such relative ease, Hale said, the astronauts will probably go ahead. "Why should I lose sleep over these gap fillers if we can take care of them that easy?" he said.
Any activity close to the shuttle could cause damage, and the repairer would have to stand on a robot arm to reach the spot.
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