SUSAN STAMBERG, host:
The space shuttle Discovery is on its launch pad poised for liftoff tomorrow. Important changes have been made since the Columbia shuttle broke up in the atmosphere more than two years ago. The cause of that failure is clear.
Mr. SCOTT HUBBARD (Scientist): In four simple words: The foam did it.
STAMBERG: Scientist Scott Hubbard was on the board that investigated the Columbia accident. They found that foam insulation falling from the shuttle's external fuel tank struck the shuttle's left wing during liftoff. It created a breach that doomed the vehicle and its crew. Accident Board Chairman Harold Gehman said NASA should try to prevent foam from shedding from the external tank.
Mr. HAROLD GEHMAN (Chairman, Accident Board): But we didn't think that saying that you've got to stop all shedding before you can launch again is reasonable, because that's not how the machine operates.
STAMBERG: The board said NASA should try to minimize the threat from falling debris, but last month an independent review found NASA had not fulfilled that requirement. NASA officials decided to go ahead with this launch anyway. `The remaining risk is acceptable,' they say. NPR's Richard Harris traveled to New Orleans, where the tanks are built, to see what NASA and its contractors have done to minimize the risk.
RICHARD HARRIS reporting:
It's not altogether an accident that the space shuttle's external fuel tanks are built on the Louisiana coast. They're as tall as a 15-story building, so big they must be shipped by barge to the Florida launch pad.
(Soundbite of machinery operating)
HARRIS: Marion Lanasa leads the way into a building so big, even these huge tanks are dwarfed.
Mr. MARION LANASA (Michoud): We're entering what is a 43-acre building under one roof. It's the main production facility for the external tank.
HARRIS: And the facility is so big, people are allowed to ride bicycles to get from point A up to point B, it looks like.
Mr. LANASA: Absolutely. It was the world's largest building under one roof when it was constructed in the '40s.
(Soundbite of vehicle reverse alarm)
HARRIS: Tanks in various stages of completion are arrayed around the Michoud Assembly Facility. As we hike across the building, Lanasa explains that once the aluminum tanks are shaped and sealed, they are covered with a vital coating of insulation.
(Soundbite of background shouting)
Mr. LANASA: Now each external tanks has two-thirds of an acre surface area that needs to be sprayed with a spray-on foam insulation. The insulation is required because of the super-cold fuels that are carried within. Liquid oxygen is 297 degrees below zero Fahrenheit; liquid hydrogen, 423 degrees below zero Fahrenheit, so cold that, if they were sitting on the launch pad in this aluminum tank, that they would form sheets of ice on the outside.
HARRIS: So the insulation is essential, but it's also a problem. A chunk of this material fell off of Columbia during its launch and breached the orbiter's wing. Hot gasses rushed into the wing as the shuttle re-entered the atmosphere and sliced its support structure like a blow torch. That caused the wing to disintegrate while the shuttle was high over Texas. Obviously, job one for returning to flight was to fix the problem of falling foam.
(Soundbite of an unidentified beeping noise)
Unidentified Man #1: Thank you.
(Soundbite of banging metal)
HARRIS: We head into another building and pass through a security turnstile.
(Soundbite of background public address system)
HARRIS: External tank 119 is lying on its side like a beached whale. It's coated with yellow foam insulation which will gradually turn orange once this tank is exposed to sunlight. This tank is also covered in places with protective paper. A dozen workers are carefully crawling over it.
(Soundbite of machinery)
Unidentified Man #2: Want duct tape?
Unidentified Man #3: Hmm?
Unidentified Man #2: Want duct tape?
HARRIS: Mike McGee explains that NASA and his employer, Lockheed Martin, focused on finding ways to get the foam to stick better in critical areas.
Unidentified Man #3: Yeah.
HARRIS: But the most obvious task was simply to get rid of any place where there was a big chunk of insulation in the first place. That was true in an area of the tank called the bipod. A wedge of foam there the size of a suitcase was what ripped free from the tank during Columbia's liftoff.
Mr. MIKE McGEE (Lockheed Martin): It went from a large block of foam that was on the bipod to now a very low-profile foam with a heater element that keeps the ice from forming on the bipod.
HARRIS: Heaters to melt ice are being installed elsewhere on the tank, too. A falling icicle could easily do more damage than falling foam, and on this day workers are preparing to install heaters on a part of the tank called the bellow.
Mr. McGEE: They're not worried about the drip lift. They're worried about the flushes on the convoluted side.
HARRIS: There are more than a dozen other major changes to the shuttle and the shuttle program. For example, in order to look for signs of falling debris during launch, NASA intends to take high-resolution videos of the liftoff from many different camera angles: from the ground, from the air and from the shuttle's under belly and, as McGee points out, even from the tank itself.
Mr. McGEE: And if you look to where the big feed-line pipe enters into the tank, and you see the small red cap...
HARRIS: Yeah.
Mr. McGEE: ...that's actually a cap to the camera. And so during launch, as the orbiter sits on top, we'll get a view from the camera down the external tank. You'll be able to see the bipods, how they're performing.
HARRIS: Those images will be beamed back to Earth, real time, to look for signs of damage during liftoff. And if all goes well, after eight and a half minutes of flight, the fuel is exhausted and the external tank is jettisoned over the Indian Ocean. It burns up in the atmosphere. McGee says at that moment, the tank people know they've done their job.
Mr. McGEE: It's an overwhelming sense of achievement when you watch this vehicle launch and you know that you've played a significant part in producing it.
HARRIS: Does it bother you even a little bit that it ultimately burns up in the atmosphere and that's it?
Mr. McGEE: Oh, no. That's what keeps us in business here. It's the only non-reuseable part, and we're more than happy to just go ahead and build the next one.
HARRIS: In fact, on this day, the next one, tank 120, is in an adjacent building.
(Soundbite of metal door)
HARRIS: You need to ride a freight elevator to get to the work platform for this tank since it's standing upright.
Unidentified Man #4: All right. Take us to the top.
HARRIS: Here workers are replacing some of the foam using a new technique that's supposed to reduce the risk that it will come off during flight.
Mr. ANDREW WILLIAMS (Michoud): ...right in the groove.
(Soundbite of brushing)
HARRIS: Andrew Williams is using a mirror and a dental tool to remove nearly invisible flakes of old insulation from behind a bolt.
Mr. WILLIAMS: Once we get that last piece of residue from back there, and then they'll spray it again. Yup.
HARRIS: Around the other side of the tank, Alan Arthur is admiring all the handiwork. He's a lead mechanical assembler, and he's been working here for 29 years. Arthur says the hardware isn't the only thing that's changed since the Columbia accident. So have the daily routines.
Mr. ALAN ARTHUR (Lead Mechanical Assembler): Actually, the--we're a lot tighter now. You know, the routine had kind of sunk in and--we can build a better tank now, I think. I think we needed some housekeeping.
HARRIS: A change in attitude is just as important as a change in hardware.
(Soundbite of man whistling)
HARRIS: The Columbia Accident Investigation Board said the cause of the accident was as much a human failing as it was a hardware failure. NASA has addressed that with a number of bureaucratic reshufflings and procedural changes. But for all this work, the truth is that it is not possible to eliminate all hazards of falling foam from the external tank. The people here at Michoud say they have done their best and NASA agrees. Richard Harris, NPR News.
STAMBERG: A time line of America's manned space program is at npr.org.
This is NPR News. Transcript provided by NPR, Copyright NPR.
