July 29, 2005
Behind Chunks of Foam, a Failure to Confront Hazard
NASA was never forced to attack shuttle debris peril, and apparently rejected wider solutions.
By Ralph Vartabedian, Times Staff Writer
In a history that includes technical setbacks and failures, NASA has always bounced back with a solution over the four decades of human spaceflight.But its finding that large pieces of foam fell off the shuttle Discovery's external fuel tank during Tuesday's launch shows that the space agency has failed to solve the cause of the Columbia accident that killed seven astronauts on their return voyage in February 2003.
In the months after the Columbia disaster, NASA learned that foam debris falling off the external tank damaged the sensitive thermal protection system on the orbiter. Columbia burned up over Texas when superheated gases penetrated its wing. NASA then spent more than two years and $1.4 billion trying to improve safety.
However, the recommendations made by Columbia's accident investigators did not force NASA to confront the problem head-on. The board told the space agency to "initiate" a program to eliminate foam debris and "initiate" a program to strengthen the orbiter's thermal protection system, but it did not make NASA adopt a 100% fix to either system.
It also appears that in 2003, NASA rejected efforts by outside experts who proposed comprehensive fixes to the foam problem, because the proposals required aggressive redesigns or advanced foam technology that might have required significant investments.The path NASA took instead was to fix, at limited cost, an old launch system that it planned to get rid of by the end of the decade.
Retired Navy Adm. Harold W. Gehman Jr., chairman of the Columbia Accident Investigation Board, acknowledged Thursday that the recommendations to NASA left open a window that would have allowed the same scenario of foam debris falling off and damaging the orbiter's thermal protection system."
We had precious little faith that they could stop this stuff from coming off," Gehman said in an interview. "And lo and behold, they couldn't."Nonetheless, Gehman defends the decision, saying any binding requirement to fix the system "wasn't reasonable."Gehman said neither his accident investigators nor NASA had any definitive explanation for why foam even fell off the tank, let alone a proposal for how to stop it."At the time, we got mixed and inconsistent explanations why foam fell off," Gehman said. "When we went into the body of research, it was inconsistent and unpersuasive."
John Logsdon, director of the Space Policy Institute at George Washington University and another member of the Columbia board, acknowledged that he thought the board should have issued a tougher recommendation on fixing the foam."Could we have been tougher? Hindsight is wonderful," Logsdon said. "We put together a set of recommendations that provided a context in which the shuttle program could move forward. They had budget and schedule constraints."
Even NASA officials acknowledged that they erred. "We decided it was safe to fly as is. Obviously, we were wrong," Bill Parsons, manager of the shuttle program, said Wednesday.
Instead of fixing the debris problem, the board focused many recommendations on allowing astronauts to survive such a foam strike. It required advanced photography of the launches to determine whether debris damaged the orbiter, a capability to repair wings in space and a rescue plan in case astronauts were marooned in orbit.
While such measures might save the lives of astronauts, they would not save the space program from a debilitating loss of another shuttle or a delay in launches, as it is now facing. NASA officials say they do not know how long it will take to fix the new foam problems or how it could affect the future of the space program. Until those solutions are in hand, the shuttles are not supposed to fly.
Outside experts tried to get NASA's attention in 2003 on advanced research they thought might help the space agency keep the foam stuck to the massive external tank. On Thursday, they said they were largely rebuffed by NASA insiders who said they did not have the resources to consider new technology.
Steve Nutt, senior associate dean for research at USC and head of the engineering department's foam research center, submitted a proposal in 2003 to NASA for a fiber-reinforced foam that his team had developed.Nutt's lab at USC pioneered a system of mixing chopped glass or aramid fibers into the foam, creating dramatic improvements in strength and the ability to resist cracking.
"They said the technology had merit, but the interest kind of dried up," Nutt said. "They said they didn't have the research-and-development budget to assess this technology."Nutt said NASA never had the information necessary to decide whether his technology would work on the shuttle. He added, "I don't want to bad-mouth NASA. I feel really sorry for those guys. I would still love to talk to someone at NASA."
A second outside proposal submitted by Oscar Weingart, a materials science expert who had spent a career in composites, suggested winding tiny lightweight filaments around the external tank. The concept would have used 800 pounds of carbon filament to create a strong net around the foam, at a cost of less than $1 million.
Several academic experts in materials technology said the proposal looked promising. Weingart, who holds five patents for filament technology, said he received a brief form letter thanking him."It went into a rat hole, as far as I can determine," Weingart said.
Apart from a major redesign, NASA also passed on even modest changes, including modifying the section that fell off Tuesday. NASA considered changes to the Protuberance Air Load ramp, or PAL ramp, in December 2004, noting that it had fallen off on two previous launches. It considered three options to fix the problem, according to NASA documents. But in the end, the agency decided it was safe to fly without any changes.
Paul Czysz, a retired professor of aerospace engineering at Washington University in St. Louis and a former NASA consultant, said in an interview Wednesday that NASA's inbred and political culture kept it from solving the foam problem after the Columbia accident. "The bureaucracy of NASA tends to reinvent what it has already done," Czysz said.
Foam has bedeviled NASA since the beginning of the shuttle program. Foam has fallen off the external tank in nearly every shuttle launch. The hard foam is intended to prevent ice from forming on the outside skin of the tank, which would represent another debris threat at launch. It also insulates the liquid hydrogen and liquid oxygen.
During launch, the foam skin is several hundred degrees on the outside and several hundred degrees below zero on the inside, while the aluminum tank is flexing, vibrating and being buffeted by aerodynamic forces thousands of miles per hour.
James McGuffin-Cawley, professor of material science at Case Western Reserve University in Cleveland, compared the situation to getting foam to stick to a soft drink can that deforms easily. "It is amazing to me that it works," he said.
Indeed, if the accident board had written a tougher recommendation, the result could have ended the shuttle program."The accident board agonized whether to write a tougher recommendation, knowing it could not be met," said Howard McCurdy, a space expert at American University. "If they had written that into the report, they knew the shuttle might not have ever flown again."But what the agency is left with is a serious crisis." The chance of a bad outcome is much greater," McCurdy said. "It is a very devastating message."
John Pike, executive director of GlobalSecurity.org, a research group in Alexandria, Va., said that accident investigators and NASA regarded the shuttle as an old system unworthy of a major investment, and that the Columbia fixes were much more modest than the fixes after the 1986 Challenger accident, which blew up on launch."Most people will not put a lot of money into a car they are planning to get rid of, and the shuttle is an old car we are getting ready to get rid of," Pike said. "They basically looked at the fixes and said, 'This is good enough for government work.' "
The shuttle grounding leaves the space program not only with a technical problem but with an international political mess, said Louis Freidman, executive director of the Planetary Society. Europe and Japan have invested billions of dollars into modules for the space station that only the shuttle can launch. If the project were to fail, it could undermine U.S. leadership in space programs and raise doubts that the U.S. could be trusted to deliver, Freidman acknowledged."The very fact that they have grounded the fleet is a very, very big deal," he said. "NASA should call an emergency meeting of the International Space Station team members and decide what they can do if the shuttle is not available."
Times staff writer John Johnson Jr. contributed to this report from Houston.