The Challenger disaster was not about an engineering failure and it was not about seven people being killed, according to Roger Boisjoly, aerospace engineer who inspected the shuttle’s O-rings prior to the fateful flight. It was about people who could not handle their professional responsibilities.

Boisjoly, who worked for the engineering firm, Morton Thiokol Inc., which was contracted by NASA at the time of the Challenger disaster, spoke Thursday night as the final lecturer in Hanover College’s “Ethical Choices, Individual Voices” series.

Boisjoly began his lecture by showing footage of the Challenger explosion and of the control room personnel as they watched the shuttle explode just 73 seconds after launch. “Nine, eight, seven, six ... We have main engine start ... five, four three, two, one ... We have lift off,” a voice said as the Challenger left the launch pad.

Audience members were filled with anxiety as they watched footage of Challenger, soaring into the air.

“Challenger go with throttle up,” the voice on the video said. A couple seconds later, the Challenger was a giant ball of fire in the sky, and workers in the space shuttle control room looked at one another, stunned. There was “obviously a major malfunction,” the voice on the video said. “Final reports ... vehicle exploded.”

Although Boisjoly was just as horrified as the control room personnel and the thousands of Americans who tuned in by television on Jan. 28, 1986, to watch the first flight to carry a teacher into space, he was not surprised that the Challenger exploded. He knew there was almost a 100 percent chance the launch would be disastrous and so did members of Morton Thiokol’s and NASA’s upper management teams.

Boisjoly began his career with Morton Thiokol in 1980. At that time, he said, it had already been determined that the shuttles’ O-ring joint design, which was blamed for causing the Challenger disaster, was faulty. But it was Boisjoly’s job to keep the O-ring joints operational. O-rings are rubber rings that seal the joint.

After every launch, Boisjoly said, he and other Morton Thiokol engineers retrieved the shuttles’ rocket fuel cylinders, which contained the O-rings, and prepared them for the next flight. Boisjoly said that when he inspected the cylinders’ O-rings following the launch that took place just before the Challenger, he found that masses of fuel had escaped past the primary seal. The O-rings were not functioning properly, he said.

Boisjoly said he determined that the cold weather that had plagued Florida that night caused the seal to fail and allowed gas to reach past the primary seal, destroying the O-rings.

The night before the launch, temperatures in Florida dipped below freezing. At the time of the launch, the outside of the fuel cylinders was 67 degrees, but inside it was only 53 degrees. The cold air, mixed with already faulty O-rings, caused the joint to loosen and allowed the gas to reach past the primary seal, Boisjoly said. “It’s my technical opinion that the cold weather that preceded” the launch is what affected the seal, he told his managers. “I estimate that we were within seconds of blowing it out of the sky.”

Boisjoly said he and other engineers were instructed to perform tests on the O-rings. Through their tests, Boisjoly said, they found that the rings had trouble sealing at 53 degrees and that if the primary seal was destroyed, the back-up seal had a great chance of failing. It had “close to 100 percent chance of destruction,” he said.

After the preliminary tests were performed, Boisjoly said, his managers wanted to keep the information that the rings had trouble sealing at 53 degrees a secret. But when NASA asked Morton Thiokol to make a presentation about the faultiness of the rings, management decided it should tell NASA about the defects, Boisjoly said.

When Morton Thiokol told NASA about the defects, Boisjoly said, they asked him and other engineers to form an unofficial task force to study the O-rings further. The task force never met, Boisjoly said.

So Boisjoly drafted a letter to his managers, stating how faulty the O-ring joint system was and the affect it could have on flights to come. “It is my honest and very real fear that if we do not take action to dedicate a team to solve the problem with the field joint having the number one priority, then we stand in jeopardy of losing a flight along with all the launch pad facility,” Boisjoly wrote. “The result would be a catastrophe of the highest order — loss of human life.”

Boisjoly said his letter never made it past the managers. They put a stamp on the document, deeming it “private,” he said.

But Boisjoly wanted his colleagues to know that he had warned management of the risks, so he whited out the private stamp and circulated a copy of his letter to his co-workers. “They’d been put on notice that I’d done this,” he said.

After Boisjoly’s colleagues found out about his letter, Morton Thiokol management put Boisjoly and other engineers on an official task team to study the O-rings. The team never met and no tests were performed, Boisjoly said. “We did not accomplish one single test on this joint or this seal, not one,” he said.

About a year after Boisjoly initially inspected the O-rings and found that the temperature had an effect on the already faulty joints, it was time for the Challenger launch. The night before the Challenger launch, Florida was to be hit again with record low temperatures, Boisjoly said. Knowing that temperatures in the high teens and low 20s could mean disaster for the flight, Boisjoly and other engineers formed a stop-launch group and met with their chain of command.

Boisjoly said that during the meeting, he and his colleagues were able to persuade their superiors to stop the flight. “We had no difficulty convincing all in the chain” not to launch, Boisjoly said. “Everybody knew we were flying on a wing and a prayer.”

But when Morton Thiokol told NASA not to launch, NASA’s upper management said they wanted to meet with the engineering firm’s management and engineers in 45 minutes, Boisjoly said. They wanted Morton Thiokol to prove the launch would fail. “We had 45 minutes to prepare for the most important meeting of our lives,” Boisjoly said.

Morton Thiokol engineers and management presented all the proof they could to NASA that the launch would be disastrous, but NASA would not back down, Boisjoly said. NASA accused Morton Thiokol of coming up with criteria the eve of the launch and it accused engineers of messing up the launch schedule, Boisjoly said.

In the mist of the pressure, Morton Thiokol managers stepped to the side, ignoring their engineers’ recommendations, and decided to make a “management decision,” Boisjoly said. They gave NASA the OK to launch with no criteria on the weather.

At launch time, the temperature was 29 degrees. Boisjoly sat in a room with his fellow co-workers and watched Challenger leave the launch pad. Everything seemed to be going well, and Boisjoly had a sense of relief when the shuttle didn’t explode on the pad as he originally predicted. But seconds later ... disaster.

Following the Challenger explosion, NASA and Morton Thiokol tried to deny that they knew about the faulty O-rings and field joints, prior to the disaster. But Boisjoly testified against them.

Boisjoly was then black-balled from the engineering business because of his testimony. But he didn’t let that stop him, going on to get his engineering license and starting his own firm.

Although his actions cost him a lot, Boisjoly said, “I would do exactly what I did again. I believe that our first responsibility is to others. I could not do anything but what I did.”

At the conclusion of the lecture, Hanover College President Russell Nichols commended Boisjoly for making the decisions he made and for taking action. “We admire and appreciate what you’ve done, and we want to thank you for what you’ve done for our country.”