RENEE MONTAGNE, host:
NASA has finished fueling the space shuttle Discovery in preparation for launch later this morning. Overnight tests of a problem fuel sensor found it is functioning normally and the seven-member crew is getting suited up. NASA says the chance of weather cooperating is now 80 percent. NPR's David Kestenbaum is at the Kennedy Space Center in Florida.
Good morning, David.
DAVID KESTENBAUM reporting:
Good morning, Renee.
MONTAGNE: What can you see from where you are?
KESTENBAUM: Well, we're set up on a grass field about three miles from the space shuttle. There's a huge digital countdown clock on the grass here. And this is actually, I'm told, a very good seat, even at this great distance. When it takes off, the ground shakes and the sound is so loud that you can't hear yourself.
MONTAGNE: Now the last launch attempt--and that was nearly two weeks ago--was scrubbed because of problems with a fuel sensor. Obviously, they're doing OK now, but what are the details on that?
KESTENBAUM: So this was a fuel gauge sensor that was measuring the amount of hydrogen in the tanks, and it failed when they ran a test the last time they tried to launch it, but they have not really been able to recreate it since, even though they've pulled everything apart and wiggled all the wires. So it now seems to be working OK. It may mean they will never know exactly what the problem was, but NASA managers said even if that particular problem reappeared, they would probably go ahead and launch because there are three other sensors and a lot more would have to go wrong before they would have, as they call it, a bad day.
MONTAGNE: Now it looks like the weather is cooperating, but there's still a 20 percent chance that things won't work out. When will they know for sure?
KESTENBAUM: That's true, and they always phrase it that way. They always say there's a 20 percent chance of it not going instead of the optimistic 80 percent. They--you know, it may take right up until launch. Although if it's clear, then obviously things will be fine. But if things are iffy, they will literally wait until the last second, I'm told, until making a decision whether to scrub or go. As you know, they have a very short launch window, 10 minutes or so.
MONTAGNE: And this is, I think, as people know, the first shuttle launch since the Columbia accident two and a half years ago. Kind of a big question for you, David. What's happened at NASA since then?
KESTENBAUM: Well, technically, they've done a lot to really try and make sure the sort of thing that happened with the Columbia doesn't happen again. And the problem there was a piece of foam that came off during launch and punched a hole or cracked one of the shuttle's wings. So they've really don't everything they can to reduce the amount of falling debris. They've taken away some of the insulating foam in some places that have sort of weird shapes where it might break off, and they've put in heaters. They've redesigned the foam in some of the joints. There are cameras all over the place now watching the launch. And they have a 100-foot boom that they'll use in orbit to inspect all the tiles and all the heat-resistant surfaces to make sure there are no cracks before they try and come back down to Earth.
MONTAGNE: You know, I read--and I would guess you know--that NASA's saying there's something like a one in a hundred chance of a problem, something like twice what they predicted...
KESTENBAUM: The number for Columbia.
MONTAGNE: ...for Columbia, yeah.
KESTENBAUM: Yeah, that's an interesting number. They used to say before Columbia that the odds were one in 254 or something catastrophic happening on the launch pad. And now they say the number's sort of one in a hundred, and they say that reflects that they know a lot more since Columbia about what can hurt the shuttle. It's one of the numbers they look at before they launch, and they try and drive it down by making things as safe as possible. But if you look at the history, the risk of failure on the launch pad with Challenger, the one failure is about one in 113. So that's about 1 percent. That's--so their estimate would be about right.
MONTAGNE: Well, David, you'll be there all morning and we'll be talking to you later.
KESTENBAUM: OK. Thanks, Renee.
MONTAGNE: NPR's David Kestenbaum at the Kennedy Space Center. Full shuttle coverage is at npr.org.
This is NPR News. Transcript provided by NPR, Copyright NPR.
