NASA details defect in shuttle's fatal foam
Agency says the process was at fault, not the workers
NEW ORLEANS - The foam that struck the space shuttle Columbia after liftoff and led to the deaths of all seven astronauts on board was defective, NASA said Friday.The space agency said that testing confirmed the Columbia Accident Investigation Board's conclusion that the foam figured in the tragedy on Feb. 1, 2003, and determined that the foam broke off the shuttle’s external fuel tank because NASA did not know its procedures for applying foam insulation were flawed.
A suitcase-sized chunk of foam from an area of the tank known as the left bipod, one of three areas where struts secure the orbiter to the fuel tank during liftoff, broke off 61 seconds into the flight on Jan. 16, 2003. Investigators say it gouged a large hole in Columbia’s left wing.
The damage went undetected during the shuttle’s 16-day mission, but caused the nation’s oldest spacecraft to break apart under the stress of re-entering the Earth’s atmosphere on Feb. 1, killing the astronauts.
“We now believe, with the testing that we’ve done, that defects certainly played a major part in the loss. We are convinced of that,” said Neil Otte, chief engineer for the external tanks project. He spoke at the Michoud Assembly Facility in New Orleans, where the half-million pieces of every shuttle fuel tank come together.
The fault apparently was not with the chemical makeup of the foam, which insulates the tanks and prevents ice from forming on the outside when 500,000 gallons (1.9 million liters) of supercold liquid hydrogen and liquid oxygen are pumped aboard hours before liftoff.
Instead, Otte said NASA concluded after extensive testing that the process of applying some sections of foam by hand with spray guns was at fault.
Gaps, or voids, were often left, and tests done since the Columbia accident have shown liquid hydrogen could seep into those voids. After launch, the gas inside the voids starts to heat up and expand, causing large pieces of insulation to pop off.
NASA said this happens on about 60 percent of its shuttle launches.
For the bipod foam, the entire ramp was apparently torn away. It weighed only 1.67 pounds (750 grams), but at the speed involved, it hit the orbiter with enough
force to shatter the reinforced carbon-carbon panels of the wing’s leading edge.
NASA has made extensive changes in the foam-application process, but still has tests and perhaps more procedural changes before the tanks can be certified for flight.
“It was not the fault of the guys on the floor; they were just doing the process we gave them,” Otte said. “I agree with the (accident investigation board) that we did not have a real understanding of the process. Our process for putting foam on was giving us a product different than what we certified.”
Recertification is now the biggest obstacle for the tank program. New standards require that no foam pieces heavier than about half an ounce can come off the tank during the first 135 seconds of flight. That is much smaller than the pieces that have routinely popped off.
NASA also hopes to recertify
the 11 fuel tanks that were ready for flight prior to
Columbia once modifications are made. Each tank
represents about a $40 million investment.
By Marcia Dunn
The Associated Press
Updated: 5:55 p.m. ET July 22, 2004
CAPE CANAVERAL, Fla. - NASA has met two more recommendations that are required for the space agency to return to flight, but remains stymied on inspection and repair methods for shuttles in orbit.
Despite the lingering hurdles, there is no reason to believe shuttle flights won’t resume next March or April, said Richard Covey, a former shuttle commander who is chairman of the task force overseeing NASA’s progress following the Columbia disaster.
The task force gave conditional approval Thursday to NASA’s response to two return-to-flight recommendations, one requiring digital photography for critical shuttle systems to augment engineering drawings and create a robust database. The other requires a standard definition for debris discovered during shuttle flight preparations.
Five down, 10 to go
For instance, the development of a boom for inspecting the underside of an orbiting shuttle is lagging, and NASA is not sure whether the device can be ready by next spring. NASA already has given up on trying to create a repair wrap for any sizable holes in the shuttle wings.
As for NASA’s inability to fix a hole as large as the one that doomed Columbia last year, Covey said the task force has yet to assess the issue. And the group is still studying NASA’s proposed use of the international space station as an emergency shelter for visiting shuttle astronauts, in case their ship is damaged beyond repair during launch.