Original URL: http://www.theregister.co.uk/2007/08/16/shuttle_repair/
NASA delays decision over Shuttle repair
Weighing up risks
NASA has put off making a decision about repairing a hole in the insulation under the space shuttle's wing until tomorrow, according to reports.
If the repair is needed, the fix will take place on the next spacewalk, slated for Saturday.
The Houston Chronicle reports that the team aboard Endeavour asked mission control whether another spacewalk was likely. Commander Scott Kelly was told: "We have no idea which way the wind is blowing at the moment."
The gash in the thermal tiles is roughly three and half inches long, by two inches wide. In one area, a one inch wide strip, the tile has been cut right through, exposing a part of the thermal fabric that covers the shuttle's frame.
The aluminium frame cannot get hotter than 350 degrees, NASA says. Simulations suggest it will heat to around 325 degrees, with the worst of the heat of re-entry skipping over the "wound".
Initial tests suggest a repair will not be needed, but this is clearly not an decision NASA can afford to get wrong. Although engineers are not worried about another catastrophic failure, as with Columbia, they are worried that over heating the area could mean long and expensive repairs once the shuttle is back on the ground.
NASA would prefer to avoid the risk of another spacewalk if it is not absolutely necessary. Leaving a spacecraft in orbit is not a safe thing to do, after all. But concerns are probably heightened, especially after the latest spacewalk was cut short when one of the astronauts noticed a two inch gash in his glove.
NASA said Rick Mastacchio was never in any danger, since only the glove's top two layers (of five) had been torn. But the reason for the tear is not clear: it could be sharp edges on the space station, but because it is the second torn glove in the last three missions, and managers are worried the suits might be showing signs of age.
Those in charge of planning the spacewalks said they would prefer not to have the team take another jaunt outside until they know why the glove tore. But the big boss, John Shannon, said he'd have no hesitation in ordering astronauts out the airlock if a repair is needed. ®