Genius

by James Gleick

  But Feynman immediately challenged Moore on the view that O-ring blow-by had been acceptable because the secondary rings had held.

  “You said we don’t expect it on the other O-ring,” Feynman said. “On the other hand, you didn’t expect it on the first O-ring… . If the second O-ring gives just a little bit when the first one is giving, that is a very much more serious circumstance, because now the flow has begun.” The air force general, Kutyna, had befriended Feynman when they sat together at the commission’s first news conference. (“Co-pilot to pilot,” he had said softly, choosing this deferential phrase out of worry that Feynman was nervous beside a general in an imposing uniform, “comb your hair,” and Feynman, surprised, growled and asked Kutyna for a comb.) Now Kutyna joined in: “Let me add to your comment… . Once it got a path, then it burns like an acetylene torch.”

  Feynman said, “I have a picture of that seal in cross section here, if anybody wants to see it.” No one responded.

  For Feynman, for Rogers, for Graham, for the press, and for NASA officials, the weekend of February 8 brought surprises.

  Feynman, away from home, thinking of his Los Alamos experience as the prototype for urgent group technical projects, did not want to take Saturday and Sunday off. Through Graham he arranged a series of private briefings on Saturday at NASA’s Washington headquarters. He learned more about the engines, the orbiter, and the seals. He found again that the agency’s engineers understood a long history of difficulties with the O-rings; that two- or three-inch segments of the thirty-seven-foot links had repeatedly been burned and eroded; that a critical issue was the speed with which the rubber had to press into the metal gap—in milliseconds; and that the space agency had found a bureaucratic means of simultaneously understanding and ignoring the problem. He was particularly struck by a summary of a meeting between Thiokol and NASA managers the previous August. Its recommendations seemed incompatible:

  • The lack of a good secondary seal in the field joint is most critical and ways to reduce joint rotation should be incorporated as soon as possible to reduce criticality… .

  • Analysis of existing data indicates that it is safe to continue flying… .

  Elsewhere at NASA headquarters that day, Graham learned that a storm was about to break: the New York Times had obtained documents showing urgent warnings within NASA about O-ring problems over a period of at least four years. Graham had taken control of the agency only recently, when the administrator, James Beggs, was indicted on fraud charges unrelated to NASA. He immediately telephoned Rogers.

  The article appeared Sunday, quoting warnings even more dire than those the engineers had shown Feynman: that a failure of the seals could cause “loss of vehicle, mission, and crew due to metal erosion, burn-through, and probable case bursting resulting in fire and deflagration,” and that

  There is little question … that flight safety has been and is being compromised by potential failure of the seals, and it is acknowledged that failure during launch would certainly be catastrophic.

  That morning Graham himself took Feynman to the Smithsonian Institution’s National Air and Space Museum, where he sat in a cavernous theater and watched an inspirational giant-screen film about the space shuttle. He was surprised at how emotional he felt.

  In the afternoon Kutyna called Feynman at his hotel. As shuttle program manager for the military, Kutyna knew the shuttle more intimately than any other commissioner. He also knew how to run a technical commission, because he had headed the air force’s own investigation into the explosion of a Titan rocket the year before. And he had his own information sources among the engineers and astronauts—one of whom told him over the weekend that Thiokol had known of a potential loss of resiliency when the rubber O-rings were cold. Kutyna wanted to bring this information into the open without jeopardizing his source. He invited Feynman to his house for Sunday dinner. Afterward they went out to his garage—he collected junk cars as a hobby, and at the moment he was working on an old Opel GT. Its carburetor happened to be sitting on his workbench. He told Feynman, you know, those things leak when it’s cold, so do you think cold might have a similar effect on the shuttle O-rings?

  Rogers called a closed meeting Monday in reaction to the New York Times revelations. He made clear that he considered them a disruption of his proceedings: “I think it goes without saying that the article in the New York Times and other articles have created an unpleasant, unfortunate situation. There is no point in dwelling on the past.” NASA representatives were asked to respond: “I think that his statement in here where he says that it might be catastrophic I think is overstated,” said one, and Rogers remarked, “Well, that may be.” Lawrence Mulloy, project manager for the solid rockets testified that the rubber in the O-rings was required to operate across an enormous temperature range, from minus 30 to 500 degrees Fahrenheit. He did not know of any test results, however, on the actual resiliency of the O-rings at low temperatures.

  Mulloy returned the next morning to give the commissioners a briefing—another in the genre that Kutyna thought of as “telling which was the pointy end of the shuttle because they don’t know that much about it.” He brought more than a dozen charts and diagrams and gave a vivid flavor of the engineering jargon—the tang end up and the clevis end down, the grit blast, the splashdown loads and cavity collapse loads, the Randolph type two zinc chromate asbestos-filled putty laid up in strips—all forbidding to the listening reporters if not to the commissioners themselves. “How are these materials, this putty and the rubber, affected by extremes of temperature? …” one commissioner asked.

  Yes, sir, there is a change in the characteristic. As elastomers get colder, the resiliency decreases, and the ability to respond——

  Now, the elastomers are what?

  That is the Viton O-ring.

  The rubber?

  Feynman pressed Mulloy on why resiliency was crucial: a soft metal like lead, squeezed into the gap, would not be able to hold a seal amid the vibration and changing pressure. “If this material weren’t resilient for say a second or two,” Feynman said, “that would be enough to be a very dangerous situation?”

  He was setting Mulloy up. He had been frustrated by the inconclusive and possibly evasive testimony. He had made an official request for test data, through Graham, and had received documents that were irrelevant, showing how the rubber responded over a period of hours instead of milliseconds. Why couldn’t the agency answer such a simple question? At dinner Monday night his eyes fell on a glass of ice water, and he had an idea that he first thought might be too easy and gauche. Ice water was a stable 32 degrees, almost exactly the temperature on the pad at the time of the launch. Tuesday morning he rose early and hailed a taxicab. He circled official Washington in search of a hardware store and finally managed to buy a small C-clamp and pliers. As the hearing began, he called for ice water, and an aide returned with cups and a pitcher for the entire commission. As a life-size cross section of the joint was passed along for the commissioners to examine, Kutyna saw Feynman take the clamp and pliers from his pocket and pull a piece of the O-ring rubber from the model. He knew what Feynman meant to do. When Feynman reached for the red button on his microphone, Kutyna held him back—the television cameras were focused elsewhere. Rogers called a short break and, in the men’s room, standing next to Neil Armstrong, he was overheard saying, “Feynman is becoming a real pain in the ass.” When the hearing resumed, the moment finally arrived.

  CHAIRMAN ROGERS: Dr. Feynman has one or two comments he would like to make. Dr. Feynman.

  DR. FEYNMAN: This is a comment for Mr. Mulloy. I took this stuff that I got out of your seal and I put it in ice water, and I discovered that when you put some pressure on it for a while and then undo it it doesn’t stretch back. It stays the same dimension. In other words, for a few seconds at least and more seconds than that, there is no resilience in this particular material when it is at a temperature of 32 degrees.

  I believe that has some signif
icance for our problem.

  Before Mulloy could speak, Rogers called the next witness, a budget analyst who had written a memorandum that formed the basis of the Times article. The analyst, Richard Cook, had noticed the O-ring problem on a list of “budget threats” month after month, had highlighted it to his superiors, and, when the disaster took place, felt certain that it had been the cause. The chairman, for the first and last time during the shuttle hearings, cross-examined a witness, through the rest of the morning and on into the afternoon, with the cold savagery of a prosecutor:

  You didn’t, I assume, make any attempt to weigh budgetary considerations and safety considerations, did you?

  Not at all.

  You weren’t qualified for that?

  No, sir… .

  You had no reason to think that people who were weighing those considerations were not qualified to do it? … You didn’t feel that you were in a position or should you make those decisions about what should be done with the space program?

  That’s right.

  And so that the memo, which has been given a great deal of attention, sort of suggests that you were taking issue with the people who were highly qualified to make those judgments, when in fact you weren’t at all? … You wrote the memo in the heat of the moment, and I assume you were, like everybody else in the country was, terribly disturbed and upset by the accident, and it was in that spirit or at that time when you wrote the memorandum. You didn’t really mean to criticize for public consumption your associates or people around you, did you?

  Yet by then it was clear that Cook had described the problems accurately. Feynman’s demonstration dominated the television and newspaper reports that evening and the next morning. Mulloy, under further questioning, made the first clear acknowledgment that cold diminished the effectiveness of the seals and that the space agency had known it, although a straightforward test in the manner of Feynman’s had never been performed. When such tests were finally performed on behalf of the commission, in April, they showed that failure of the cold seals had been virtually inevitable—not a freakish event, but a consequence of the plain physics of materials, as straightforward as Feynman had made it seem with his demonstration. Freeman Dyson said later, “The public saw with their own eyes how science is done, how a great scientist thinks with his hands, how nature gives a clear answer when a scientist asks her a clear question.”

  One extraordinary week had passed since Feynman boarded the night flight to Washington. The commission had four months of work remaining, but it had arrived at the physical cause of the disaster.

  As the seventies began and the last of the moon landings drew near, NASA had become an agency lacking a clear mission but maintaining a large established bureaucracy and a net of interconnections with the nation’s largest aerospace companies: Lockheed, Grumman, Rockwell International, Martin Marietta, Morton Thiokol, and hundreds of smaller companies. All became contractors for the space-shuttle program, formally known as the Space Transportation System, initially intended as a fleet of reusable and economical cargo carriers that would replace the individual one-use rockets of the past.

  Within a decade, the shuttle had become a symbol of technology defeated by its own complexity, and the shuttle program had become a symbol of government mismanagement. Every major component had been repeatedly redesigned and rebuilt; every cost estimate offered to Congress had been exceeded many times over. Unpublicized audits had found deception and spending abuses costing many billions of dollars. The shuttle had achieved a kind of Pyrrhic reusability: the cost of refurbishing it after each flight far exceeded the cost of standard rockets. The shuttle could barely reach a low orbit; high orbits were out of the question. The missions flown were a small fraction of those planned, and—despite NASA’s public claims to the contrary—the scientific and technological products of the shuttle were negligible. The space agency systematically misled Congress and the public about the costs and benefits. As Feynman stated, the agency, as a matter of bureaucratic self-preservation, found it necessary “to exaggerate: to exaggerate how economical the shuttle would be, to exaggerate how often it could fly, to exaggerate how safe it would be, to exaggerate the big scientific facts that would be discovered.” At the time of the Challenger disaster the program was breaking down internally: by the end of the year both a shortage of spare parts and an overloaded crew-training program would have brought the flight schedule to a halt.

  Yet the report of the presidential commission, issued on June 6, began by declaring that the accident had interrupted “one of the most productive engineering, scientific, and exploratory programs in history.” It attributed to the public “a determination … to strengthen the Space Shuttle program.”

  When Feynman talked about his role later, he fell back on his boy-from-the-country image of himself: “It was a great big world of mystery to me, with tremendous forces… . I hadda watch out.” He claimed no understanding of politics or bureaucracies. These were matters beyond the ken of a technical fellow. Alone among the commissioners, however, Feynman worked to expand the scope of the investigation to include precisely the areas about which he disavowed competence: issues of decision making, communication, and risk assessment within the space agency. Kutyna told him he was the only commissioner free of political entanglements. Despite Rogers’s disapproval he insisted on conducting his own lines of inquiry and traveled alone to interview engineers at the Kennedy Space Center in Florida, the Marshall Space Flight Center in Alabama, the Johnson Space Center in Houston, and the headquarters of several contractors. In between, he made repeated visits to a Washington hospital for blood tests and medication for his worsening kidney, and he talked by telephone with his doctor in California, who complained about the difficulty of practicing medicine at long distance. “I am determined to do the job of finding out what happened—let the chips fall!” he wrote Gweneth proudly. He enjoyed the thrill of the game, and he suspected that he was being carefully managed. “But it won’t work because (1) I do technical information exchange and understanding much faster than they imagine”—he was, after all, a veteran of Los Alamos and the MIT machine shop—“and (2) I already smell certain rats that I will not forget.”

  He tried to make use of his naïveté. When Rogers showed him a draft final recommendation, effusive in its praise of the space agency—

  The Commission strongly recommends that NASA continue to receive the support of the Administration and the nation. The agency constitutes a national resource and plays a critical role in space exploration and development. It also provides a symbol of national pride and technological leadership. The Commission applauds NASA’s spectacular achievements of the past and anticipates impressive achievements to come… .

  —he balked, saying he lacked expertise about such policy matters, and he threatened to withdraw his signature from the report.

  His protest was ineffective. The language appeared virtually intact, as the commission’s “concluding thought” rather than a recommendation. Although the commission learned that the decision to launch had been made over the specific objections of engineers who knew of the critical danger from the O-rings, the final report did not attempt to hold senior space-agency officials responsible for the decision. Evidence emerged showing that the history of O-ring problems had been reported in detail to top officials, including the administrator, Beggs, in August 1985, but the commission chose not to question those officials. Feynman’s own findings, substantially harsher than the commission’s, were isolated in an appendix to the final report.

  Feynman analyzed the computer system: 250,000 lines of code running on obsolete hardware. He also studied in detail the main engine of the shuttle and found serious defects, including a pattern of cracks in crucial turbine blades, that paralleled the problems with the solid rocket boosters. Overall he estimated that the engines and their parts were operating for less than one-tenth of their expected lifetimes. And he documented a history of ad hoc slippage in the standards used to certi
fy an engine as safe: as cracks were found earlier and earlier in a turbine’s lifetime, the certification rules were repeatedly adjusted to allow engines to continue flying.

  His most important contribution to the understanding of the disaster came in the area of risk and probability. He showed that the space agency and its contractors—although the essence of their decision making lay in weighing uncertainties—had ignored statistical science altogether and had used a shockingly vague style of risk assessment. The commission’s official findings could do no better than quote Feynman’s comment during the hearings that the decision making became

  a kind of Russian roulette… . [The shuttle] flies [with O-ring erosion] and nothing happens. Then it is suggested, therefore, that the risk is no longer so high for the next flights. We can lower our standards a little bit because we got away with it last time… . You got away with it, but it shouldn’t be done over and over again like that.

  Science has tools for such problems. NASA was not using them. A scattering of data points—for the depth of erosion in O-rings, for example—tended to be reduced to simplistic, linear rules of thumb. Yet the physical phenomenon, a hot jet of gas carving channels in rubber, was highly nonlinear, as Feynman noted. The way to assess a scattered range of data was through probability distributions, not single numbers. “It has to be understood as a probabilistic and confusing, complicated situation,” he said. “It is a question of increasing and decreasing probabilities … rather than did it work or didn’t it work.”