CAPE CANAVERAL, Fla. — A cracked tile and protruding ring on shuttle Endeavour are too small to pose any danger during next week's trip home from the International Space Station, NASA managers said Friday.
In fact, the space shuttle's entire heat shield is solid for re-entry based on five days of intensive photo and data reviews, said LeRoy Cain, chairman of the mission management team.
The good news came as the 11 astronauts prepared to enter the space station's newest room, Tranquility.
Astronauts hooked up the 23-foot chamber early Friday during the first spacewalk of shuttle Endeavour's visit. The room has an observation deck with seven windows, one of them the biggest ever flown in space.
The two crews also planned to open the hatches Friday night between Tranquility and the domed lookout — the $400 million-plus contributions of the European Space Agency.
During a spacewalk tonight, the astronauts will connect Tranquility's plumbing. The hoses for ammonia coolant had to be refashioned from spares, after the originals failed testing last month.
The tile and ring damage to Endeavour's cockpit was discovered Wednesday. The thermal tile was fixed before the flight, but the repair failed and the original 2-inch crack reappeared. As for the 1-inch-diameter ceramic spacer ring, it's sticking out slightly near one of the commander's windows.
The defective pieces are so small that even if they managed to break off during re-entry and strike Endeavour — a big if — no serious damage would result, Cain said.
One end of a long metal seal also is sticking up 2 inches to 3 inches on Endeavour's left wing, but it, too, is of no concern.
As for the fuel-tank foam insulation lost during Monday's liftoff, a fair amount broke off a central area that had experienced trouble on previous flights. Platforms used to inspect this so-called intertank region are positioned in such a way that makes it difficult to properly clean there, and that's causing all the trouble, Cain said. NASA will conduct extra checks of the fuel tank that will be used to launch Discovery next month. The mid-March liftoff could end up being delayed for another reason: Cold weather at Kennedy Space Center is stalling launch preparations.
Foam loss has been a major focus at NASA ever since a large chunk crippled Columbia in 2003 and led to its destruction during re-entry. NASA plans to keep up its foam vigilance, even though just four shuttle launches remain.