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Shuttle Launch Scrubbed Due to Sensor


From NPR, this is ALL THINGS CONSIDERED. I'm Robert Siegel.

And for seven space shuttle astronauts, it was a case of all suited up and nowhere to go. NASA called off today's launch of the space shuttle Discovery less than two and a half hours before launch. The problem involved one of the external fuel tank's four fuel sensors. A similar problem cropped up during tests in April. NPR's Richard Harris is at the Kennedy Space Center, and he joins us.

Richard, what exactly went wrong that caused them to scrub the launch?


Well, Robert, there are fuel tank sensors that are inside these fuel tanks in case they run dry. That would be very bad for the space shuttle engines. And there are four of them 'cause they need a redundancy to make sure that--this really is important that it not happen. And one of the four was stuck. It was not operating correctly. And even though the other three were working, the rules of flight say if you don't have all four, you can't fly. So the astronauts were mostly strapped in. They were excited. You could see the enthusiasm on their faces. And they said, `Sorry, guys.'

SIEGEL: `Not so fast.'

HARRIS: And they unstrapped them. `Not so fast.' They unstrapped them. They got back in their little silver van and were taken back to their crew quarters here. And they started to unload all the fuel that they've got on the fuel tank, and they're--in order to figure out what exactly is going wrong here.

SIEGEL: Well, what do they do now? How do they plan to locate the fault?

HARRIS: Well, it's a very tricky business. They first thing they do after the fuel is out is they'll put a big structure back against the shuttle, a sort of a work frame. And they'll see if they can figure it out without doing anything drastic, like moving the space shuttle back to its hangar, which would be a huge delay. So they're going to see if they get lucky and find it easily by checking the easiest things to check. But they're going to be working overnight, and they'll hope they'll at least have an idea of where to go next and what to do. There'll be meetings tomorrow where they'll really put together a really formal plan about how they're going to attack this problem and, they hope, solve it.

SIEGEL: But it sounds like they don't expect the problem to be solved by, say, tomorrow at this time.

HARRIS: No. In fact, the most optimistic scenario is that launch could be Saturday, but that's if they get very lucky. The other scenarios are--who knows? If they have to bring the shuttle back off the launch pad, it very likely means that it--won't be able to bring it back out to the launch pad by the end of July, which is the end of this launch window, so that means the launch would slip till September. So that's the worst case, I guess. And the best case is--Who knows?--maybe this weekend.

SIEGEL: Now this wasn't a new problem. They had experienced a problem with a fuel tank sensor before.

HARRIS: They had, yeah.

SIEGEL: Why didn't they catch it?

HARRIS: Well, it was a very vexing problem. They were just doing a fuel test in April. It was not right before a launch, the way this one was. But they filled up the tanks to make sure everything was working right, and lo and behold, this was not working right. They worked very hard to troubleshoot it. They thought of everything they could, and they could not find the source of the problem. And they are--these are the worst kinds of problems to have, where you say, `I know it's not right, and what's going on?' And you can't do it. What they did was they replaced a bunch of parts, and they looked at everything, and they tested everything. And sort of taken apart, everything seemed to work fine. And they said, `Well, we'll put it back together. We hope it works.'

And they would know because they knew that this test was coming up before launch. There was no possibility it would launch with this flaw undetected. So they were taking a chance essentially that when they put it all back together and had it on the launch pad and ready to go, whatever they did by tinkering with it would fix it. And they lost that gamble, unfortunately.

SIEGEL: Does this launch seem jinxed to you, or is this normal for a shuttle launch?

HARRIS: Well, jinxed? Not jinxed, no.

SIEGEL: Not a scientific term, I understand.

HARRIS: No, absolutely not. But many, many launches have a lot of glitches, and it's probably the exception more than the rule that they get off on the first try. So things happen. And astronauts get excited and anxious and ready to go, and they're told, `Sorry, guys, not today.' And that's tough. I guess maybe the expectation was, `We've been waiting for almost two and a half years for this launch. They've had plenty of time to think about it and get rid of all the problems leading up to it.' And evidently that was not the case today. So there are some long faces here at the Kennedy Space Center today. That's for sure.

SIEGEL: Well, NPR's Richard Harris at the Kennedy Space Center, thanks for talking with us.

HARRIS: My pleasure. Transcript provided by NPR, Copyright NPR.

Award-winning journalist Richard Harris has reported on a wide range of topics in science, medicine and the environment since he joined NPR in 1986. In early 2014, his focus shifted from an emphasis on climate change and the environment to biomedical research.