Atlantis stay extended to fix insulation blanket

The extended mission is likely to involve adding a fourth spacewalk to reseat the insulating blanket. Blankets are used on the top of the shuttle instead of the more heat-resistant tiles that cover the bottom because the heat during re-entry is much higher on the bottom of the shuttle than on the top.

Analysts said the blanket pulled up because of wind forces and not because of any impact with launch debris. It exposed a 4-inch-by-6-inch area of the graphite epoxy honeycomb underneath.

Initially, NASA experts all but dismissed the pulled-up blanket as a minor problem best addressed by leaving the blanket alone. But John Shannon, the chairman of the mission management team, said on Monday night that analysis led his team to take a cautious approach. The honeycomb, Shannon said, degrades at a lower temperature than the 1,000 degrees that can be expected during the 15-minute period of peak heating during entry. “How long it would take to completely erode is very questionable; no one could give me that answer,” he said.

“So the right answer here, the better part of valour, was to go and …secure it,” Shannon said. Analysts are still trying to determine the best way to fix the problem, he said, but it might come down to something as simple as folding the blanket back in place.