Soon after the accident, there were rumors of a meeting that took place the night before the launch that should have stopped it but didn’t. Just like the press, the public affairs office hears hundreds of rumors and has to determine whether they’re accurate before reacting in one way or another.
This one turned out to be true.
More than thirty Thiokol engineers, managers, and even vice presidents discussed concerns about the O-rings and cold temperatures with another half dozen or more officials from the Marshall Space Flight Center the day before launch.
These same concerns had been the subject of memos and warnings for years, but somehow were not discussed in the launch readiness reviews for Challenger. The Marshall solid-motor managers had gotten used to seeing hot gases get past the primary O-rings on the field joints and were trusting the secondary O-rings to prevent a breach.
In addition, dozens of engineers and managers who had been involved in examining motors after they flew had seen the blowby of hot gases and soot past the primary O-ring and some erosion of the secondary O-ring.
Yet, despite having all of the right people looking at the concerns, the information never reached final decision makers like Launch Director Gene Thomas and Associate Administrator Jesse Moore.
If I had any doubts about the value of having a presidential commission investigate the Challenger disaster, the hearings put those doubts to rest.
Without the commission, the story would have come out eventually in the course of the investigation. But written reports don’t have the drama of courtroom-style testimony, or make as great an impression on people, whether within the program or in the general public. Nor, I think, would the launch decision process, the design concerns, and the technical details of the hardware have ended up being taught in almost every engineering school in the world had the information been presented differently.
The press played an important role as well. Once the cause of the accident was known, reporters scrambled to see how long the O-ring problem had been known. The New York Times and Washington Post printed articles revealing that even a budget analyst, Richard Cook, had mentioned O-ring concerns, pointing out the impact of an accident on future budgets. They also reprinted memos from Thiokol SRB Engineer Roger Boisjoly, in which he warned management about the danger.
The articles caught Commission Chairman Rogers’s eye. The first day of hearings began with lengthy tutorials on the workings of every element of the space shuttle. Members learned about NASA’s multilayered management system for complex programs like the shuttle and Apollo before it. The Kennedy Space Center and its contractors were responsible for launch processing and launch. The Marshall Space Flight Center in Huntsville, Alabama, and its contractors were responsible for the development and manufacture of the external tank, the engines for the orbiters, and the solid rocket motors. The Johnson Space Center was responsible for the orbiter, astronaut training, and management of the mission once the vehicle cleared the tower.
Near the end of the first day, Rogers elicited the information he was really looking for when Marshall’s Larry Mulloy introduced Allan McDonald into the conversation. McDonald was Morton Thiokol’s solid rocket motor director, and he revealed the opposition to the launch by the Thiokol SRB engineers. It didn’t come out in one cohesive story, but with McDonald’s help the Commission was finally on the right path.
Shortly after noon on January 27, the team learned that temperatures of twenty degrees Fahrenheit were forecast for launch morning. Marshall’s Solid Rocket Motor (SRM) Manager Larry Wear called Robert Ebeling, a counterpart at Morton Thiokol in Wasatch County, Utah, where the SRMs are manufactured. Wear asked Ebeling to have his engineers review the effect of very cold weather on the performance of the motors.
The twelve-foot-diameter, twenty-foot-long solid motor segments were transported from Utah to the Kennedy Space Center by railway car and then stacked together to form the complete motor. The segments fit together similarly to tongue-in-groove flooring, except that the tongues were thick steel and pinned together with 180 one-inch diameter steel pins around the circumference at each joint. Since these segments were assembled away from the factory, they were called field joints.
The Thiokol engineers’ consensus was that the cold would affect the ability of the rubberlike Viton O-rings to seal the field joints in the solid motors, thereby allowing the six-thousand-degree gases to escape from the joints. They recommended that the launch be delayed until at least noon to allow the temperature to rise.
In order to include more of the SRM engineers and managers, another teleconference was arranged for eight fifteen p.m. This time, thirty-four engineers and managers participated, including high-level Thiokol and NASA/Marshall Space Flight Center managers.
Thiokol Vice President Joe Kilminster started the conference by stating that Thiokol could not recommend a launch when the temperature was “below fifty-three degrees Fahrenheit.”
NASA SRB manager Mulloy bridled, reminding everyone that no launch-commit criteria had ever been established based on temperature. “My God, Thiokol, when do you want me to launch, next April?” he concluded.
NASA Deputy Director of Science and Engineering George Hardy added that he was “appalled” at the Thiokol recommendation.
Rather than continue, Kilminster asked for, and was granted, a five-minute recess to discuss the situation off-line with the Thiokol engineers and managers.
During the break, two engineers, Roger Boisjoly and Arnie Thompson, used sketches and photographs to explain the effect of cold on the O-rings. Boisjoly had fought hard to get a new design for the SRB joints. His memos detailing the problem and the length of time it had been known to Thiokol and NASA/Marshall managers were important pieces of the puzzle for the Commission and the press.
The O-rings had been damaged slightly on twelve of the twenty-four shuttle flights prior to Challenger. This had allowed hot gases to penetrate the primary O-ring, but the secondary seals had always held. A task force had been established to look into the problems the previous year but was not given enough funding or priority to proceed quickly.
One impediment to making a clear-cut decision was that the O-ring erosion had occurred when the weather was warm as well as cold.
Finally Thiokol Senior Vice President Jerry Mason said, “We have to make a management decision.”
Three out of the four Thiokol managers voted to go ahead with the launch. Engineer Robert Lund still supported the engineering position. Mason told him, “Take off your engineering hat and put on your management hat.” Lund finally agreed to vote with the others.
When the teleconference was resumed, Kilminster told the NASA managers that Thiokol had reversed its no-go recommendation and was ready to proceed to a launch. Thiokol was asked to put the recommendation in writing. The teleconference ended about eleven fifteen p.m.
Allan McDonald, Thiokol’s SRM director, was already at KSC for the launch and not involved in the off-line deliberations. He told the NASA/Marshall managers at KSC, “If anything happens to this launch, I don’t want to be the person that has to stand in front of a board of inquiry to explain why we launched outside the qualifications of the solid rocket motor or any shuttle system.” He listed three reasons why the launch should be postponed: O-ring problems, booster recovery ships heading into wind toward shore due to high seas, and icing conditions on the launch pad.
McDonald was told in the meeting with Mulloy and others that “those are not your concerns,” but that his comments would be passed on in an advisory capacity. McDonald’s advice was not passed on, and the countdown continued.