NASA OKs Endeavour to Return to Earth
With the last bit of shuttle imagery analyzed, NASA cleared Endeavour on Monday for its return to Earth, bringing the spaceship home a day early because of hurricane worries that later evaporated. Endeavour is aiming for a touchdown early Tuesday afternoo
Mission managers gave Kelly the go-ahead after engineers finished evaluating the latest laser images of the shuttle's wings and nose and concluded there were no holes or cracks from micrometeorites or space junk. The astronauts inspected the especially vulnerable areas Sunday, after undocking from the international space station.
NASA reiterated Monday that the unrepaired gouge in Endeavour's belly will pose no danger to the shuttle or its seven astronauts during the hourlong descent. A week of thermal analyses and tests also indicated that no lengthy postflight repairs should be required either, said flight director Steve Stich.
Stich noted, however, that re-entering the Earth's atmosphere is always risky, just like a launch, and he will not relax until the shuttle is on the runway and the astronauts are safely out.
A piece of foam insulation or ice from a bracket on the external fuel tank broke off at liftoff Aug. 8, fell onto a strut lower on the tank, then bounced into Endeavour and gashed it. The same brackets have shed debris in previous launches, but it wasn't until Endeavour's flight that it caused noticeable damage.
NASA does not plan to launch another space shuttle until the problem is solved. Engineers met Monday to discuss possible remedies. A permanent solution, replacing the aluminum alloy brackets with titanium ones requiring less insulating foam, won't be ready until spring. That leaves three missions at risk, including the next one, currently set for October.
Shuttle program manager Wayne Hale said at the least, the amount of foam probably will be reduced on the tank brackets before the next flight. NASA didn't modify the brackets sooner because engineers thought the risk was "rather low" that a piece of foam or ice from that area might break off and do serious harm to the shuttle.
NASA thought any debris from the bracket would shatter when striking the lower strut on the tank; they didn't anticipate it might remain intact and slam into the shuttle as it did during Endeavour's launch. Hale called it an "unlucky bounce."
"We didn't think that could happen before," Hale said. "Clearly, we're smarter now."
Endeavour's two-week mission wasn't supposed to end until Wednesday, but over the weekend mission managers decided to cut its space station visit short. At the time, it was uncertain whether Hurricane Dean might threaten Houston, home to Mission Control.
The forecast Monday afternoon had Houston out of harm's way. But with the shuttle astronauts already packed up, NASA held to a Tuesday landing.
During a question-and-answer session with Canadian children, Kelly explained that the hurricane wasn't affecting landing preparations in orbit. "Even though we undocked a day early," he said, "we might not have to get home on Tuesday as urgently as we did before."
Teacher-astronaut Barbara Morgan took part in the education session, along with Canadian astronaut Dave Williams, who performed three spacewalks to install new space station parts.
Morgan—who was the backup for Christa McAuliffe, who died in the 1986 Challenger disaster—left two mini-greenhouses at the space station. Station resident Clay Anderson will grow basil seeds in them; youngsters will do the same on Earth using the 10 million basil seeds that Morgan carried into space.
"I'm hoping to keep these bad boys (the seeds) going for quite a while if I can," Anderson told Mission Control.
He jokingly added: "Tell Miss Morgan that I'm going to write 100 times on the side of the water delivery system, 'I will not pull the plugs too quickly, I will not pull the plugs too quickly.' "
AP Last Mod: 21 Ağustos 2007, 12:29