ROBERT SIEGEL, host:
From NPR News, this is ALL THINGS CONSIDERED. I'm Robert Siegel.
After days of discussions, NASA is about to announce whether it will send astronauts on a spacewalk to repair a small gash on the belly of space shuttle Endeavour. If NASA decides to go forward, it would be the first time the agency has tried to patch a shuttle's heat shield while in space.
And here to fill us in is NPR's Nell Greenfieldboyce who covers NASA for us. Welcome.
NELL GREENFIELDBOYCE: Thank you.
SIEGEL: And remind us again, what exactly is NASA worried about here?
GREENFIELDBOYCE: Well, if you'll recall, space shuttle Endeavour has a gash on the heat shield on its belly. It's not a very big gash. It's about the size of the palm of your hand. But in part of that gash, it goes all the way through the heat-resistant tiles that protects the shuttle as it's reentering the Earth's atmosphere.
If you look through the little sliver that's open, you can see this felt-like material that's covering the shuttle's aluminum frame. Now, NASA says this gash is no danger to the crews' safety. They think the shuttle can come home safely. It won't be a disaster like Columbia. But they are worried that during reentry, this area could experience more damage that would require repairs on the ground that could delay future missions.
SIEGEL: Well, then why don't they just decide to fix it up there?
GREENFIELDBOYCE: Some people have been saying that. They say, well, why don't you just go ahead and fix it? What's the problem? The thing is, that's not how NASA works. NASA is very deliberate. They like to study things very carefully. And you have to think about the facts that to fix it, you have to send astronauts out on a spacewalk. And spacewalks can be risky business, especially in this case because to get to the injured area, you would have to put two astronauts out on 100-foot robotic arm. You'd have to send them up and over and around the shuttle.
They could knock the shuttle and create more damage. And then once they're there, they would repair the spot with this kind of goo. It's a kind of caulking material. It hasn't been tested in space before. And if you've ever tried to caulk something, you know it can be sort of hard to control where that goes. So there is some concern that in trying to fix it, they could make things worse.
SIEGEL: Do the astronauts themselves admit to any concerns about this?
GREENFIELDBOYCE: They say not. They say they're very comfortable. The commander says he'd be happy to fly the shuttle home as is. They also say if they're told to go fix it, they'd be happy to do that on Saturday. And they've spent most of the day sort of practicing and going over exactly what they would do.
SIEGEL: Now, the very mention of a gash caused by a piece of foam reminds us of the accident that involved foam, the accident that doomed the space shuttle Columbia. Why is foam such a problem?
GREENFIELDBOYCE: Well, NASA has said that although it would like to, it can never prevent foam from falling off the tank entirely. What they're trying to do is just minimize the foam loss as much as possible. And since Columbia, they've made a whole slough of changes to the tank. And they have succeeded to a certain extent. But obviously, in this case, a fairly good-sized piece fell off and it did cause some damage. So over the next couple of days, they're going to be looking at this to see if any additional changes need to be made to the tank before they're going to fly the next shuttle mission.
SIEGEL: And when is the next shuttle mission?
GREENFIELDBOYCE: That's currently scheduled for October.
SIEGEL: For October. Thank you. That's NPR's Nell Greenfieldboyce.