The Space Shuttle Challenger Disaster

In January 1986, 7 astronauts were killed when the challenger space shuttle exploded just over a minute into the flight. The solid rocket booster O-rings failed to seal properly, allowing hot combustible gases to leak from the side of the booster, burning through the external fuel tank. There were several factors to the failure of the O-ring; including a faulty design of the solid rocket boosters, insufficient low-temperature testing of the O-ring material, and the joints that the O-ring sealed with. The lack of suitable communication between different levels of NASA management and various ethical issues ultimately lead to the disaster.

SRBs (solid rocket boosters) are key elements in the operation of the space shuttle, without them, the shuttle produces insufficient thrust to overcome the earth’s gravitational pull to achieve orbit. An SRB is attached to each side of the external fuel tank; each SRB joint is sealed by two O-rings; the bottom and top rings are known as the primary and secondary rings respectively. The purpose of the O-rings is to prevent hot combustion gases from escaping from the inside of the motor. To create a barrier between the rubber O-rings and the combustion gases, a heat-resistant putty is applied to the inner of the joint.

In general, solid rockets produce more thrust per pound than their liquid fuel counterparts. However, there is a drawback. Once the solid rocket fuel has been ignited, it cannot be turned off let alone controlled. So, it's crucial that the shuttle SRBs were properly designed.

Launch Delays

The first delay of the Challenger mission was due to a weather front that was expected to move into that area, bringing rain and cold temperatures. Usually, a mission won’t be postponed until the weather entered the area, however, the Vice President was to be present for the launch, and NASA officials wanted to avoid the necessity of the Vice President having to make an unnecessary trip to Florida, and so they postponed the launch early. The Vice President was a key spokesperson for the President on the space program, and NASA coveted his goodwill. The weather front stalled; the launch window had perfect conditions, but the launch had already been postponed. As shown in Figure 2², the lowest temperature experienced by the O-rings in any previous mission was 53℉, showing no temperature data below this recorded temperature.

Bob Lund concluded that 53℉ was the only low-temperature data that Morton-Thiokol had for the effects of cold temperatures on operational boosters, hence since his engineers had no low-temperature data below 53℉, they could not prove it was unsafe to launch at lower temperatures.

Another delay was caused by a defective micro switch in the hatch locking mechanism and problems in removing the hatch handle. However, by the time these problems had been sorted, winds became too high and so the weather front had started moving again, bringing record low temperatures to the Florida area.

Launch analysis

According to the book ‘The Final Voyage’, the temperatures during the night before the launch dropped to as low as 8℉, much lower than expected. Safety showers and fire hoses had been turned on to keep water pipes in the launch platform from freezing. Ice had formed all over the platform, and so there were concerns that the ice would fall off the platform during launch and damage the heat-resistant tiles on the shuttle. The ice inspection saw this as a great concern, but the launch director decided to go ahead with the countdown.

Post Launch Analysis

At Launch, the impact of the ignition broke loose a shower of ice from the platform, striking the left-hand booster. Although there was no evidence of any ice damage to the Orbiter itself, NASA's analysis of the ice issue was wrong. The primary O-ring was too cold to seal properly, the heat-resistant putty that protected the O-rings from the fuel collapsed, and so gases of over 5000℉ burned past both O-rings.

Eight 100ths of a second after ignition, the shuttle lifted off. The camera focused on the right-hand booster and showed about 9 smoke puffs coming from the booster at the rear field joint. Oxides from the burnt propellant temporarily sealed the field joint before flames could escape.

Issues arising from the Space Shuttle Challenger Disaster

As young engineering students, what do we see as the future for professional responsibilities as engineers? Public Welfare? Keeping loyal to your job?

It is important for experienced engineers such as those placed in management positions do not completely ignore their own experience as well as consider the decisions and understandings from the younger practicing engineers. For technical matters, practicing engineers will be more up-to-date.

Another issue is the fact that managers encouraged launching, due to insufficient low-temperature data. As there was not enough data available to make an informed decision, it was not in their opinion to stop the launch. Earlier on in a previous issue, NASA was alerted about problems in the booster design, yet they did not halt the program until the problem was solved.

On one hand, testing designs for implications are always a major priority to ensure the safety of the shuttle. However, they must also be aware of their obligation to society, to protect the public welfare. The public has provided engineers, through tax base and legislation. In return, engineers have a responsibility to protect the safety and well-being of the public in all their efforts. According to the ASME Code of Ethics, the first canon urges engineers to 'hold paramount the safety, health, and welfare of the public in the performance of their professional duties.' The welfare and safety of the public should be at the top of their priority list. Although company loyalty is important, it should not overrule the engineer’s obligation to the public. If engineers have the utmost selfish or unselfish loyalty to engineering, it can result in the most unfortunate consequences.

Ethical Issues of the Space Shuttle Challenger Disaster

Professional Responsibility

One of the main ethical issues was the professional responsibility of design engineers. Design Engineers have the responsibility of keeping designs flawless and professional, however, there are implications such as cost to build and obtain items to complete the project. Since the design team project could potentially delay the Challenger shuttle from completing its scheduled mission, the execution window was very short. From an ethical standpoint, it seemed as though the rushed schedule portrayed the management team as though they were not even concerned about the astronaut's safety.

According to software and recent Challenger historian Richard Feynman, it seemed as though engineering can only be as good as management. For the Challenger to have become a more accomplished project, the management would have to agree and listen to the case issues that the engineers had; they just dismissed the issues. Yes, the engineers had to work under a time constraint, but the management team stood in their way of performing to what they were capable of.

Effective Communication

Another big main contributing ethical factor to the disaster was a lack of effective communication between the engineers and management. After the incident, Roger Boisjoly, an engineer who worked for Morton-Thiokol, stated that the meetings preceding the challenger were filled with ‘’intense customer intimidation’’⁴. The atmosphere was too pressurized to be able to express all their concerns about the SRB. The inability of the Morton-Thiokol engineers to convey their concerns to the NASA management and convince them to postpone the launch is a large factor that ultimately led to the disaster. Choosing to hide their concerns perhaps in fear of those in management not listening to them regardless. There was also a big failure in communication between the grounds crew and NASA management. The grounds crew measured the thickness and temperature of the ice on the shuttle before the launch. The temperature recorded was 8℉, much lower than what the O-rings were designed to be used in. However, this vital piece of information was never conveyed to NASA’s managers or engineers because the grounds crew was only instructed to report on the thickness, not temperature.

Pressure on an unrealistic target

NASA had excessive pressure to increase their flight rate, the increase would ultimately reduce NASA’s ability to address urgent issues due to fewer employees dedicated to specific launch schedules. This also would then create pressure on NASA’s management team to rush their judgment on critical issues that could potentially delay any launch schedules. The difficult flight plan portrayed the management team as though keeping to the schedule was more important than the astronaut’s safety. This is unethical as people’s safety should always be the number one priority, especially when dealing with such an immense situation as going to space.

Unsafe Launch Conditions

As previously mentioned, the lack of communication between the Morton Thiokol engineers and the NASA management team to make decisions played a big role in the challenger disaster. The inability to come to a consensus between the two is what ultimately lead to the launch of the shuttle. The ethical issue is that NASA chose to take a risk by launching the shuttle despite numerous requests to delay it. Even if delaying the launch would most definitely not please anyone, the decision was needed to put the astronaut’s safety first. According to the National Society of Professional Engineers, the most important principle is to ‘’hold paramount the safety, health, and welfare of the public.’’ In any situation whatsoever, when human life is potentially on the line, every single possible issue should be dealt with before the mission or action takes place. NASA decided to go ahead with the mission to please the pressuring customers. Instead, the complete opposite happened, millions of dollars were spent at the expense of multiple lives lost.

Reliance on Emergency Safety Controls

In the event of an O-ring sealing issue, a secondary O-ring had been designed as a backup safety control measure in the even of the primary seal’s failure; and so, the situation was not deemed critical since there was the secondary O-ring. It seems to me, very unethical to deem the issue as uncritical due to the fact there was a backup that should be safe; you clearly shouldn’t let a mission go ahead if you know there is even a slight chance of the primary O-ring failing, relying solely on the secondary backup O-ring should not have to happen. To resolve this ethical issue, NASA should have stopped all shuttle launches until the seal issue can be fully corrected. Is ethically and morally wrong to gamble with the lives of others, nor to assume that the safety control measure will be able to function as the primary method of control.

As stated in the Federal Aviation Regulations, NASA engineers have now developed a ‘’Personal Cabin Pressure Altitude Monitor and Warning System’’ that monitors cabin pressure and when supplemental oxygen should be used. This model is now one of many examples of the newest innovations that were implemented by NASA, to ensure that the astronaut’s safety is fully prioritized. Although back in 1986 there wasn’t access to the latest advances in technology that we have now, so designing such a system back then would be greatly unrealistic; NASA should have originally developed some sort of system to ensure the astronaut’s safety in the event of a malfunction.

To conclude, we as engineers are the ones responsible for the designs and development of new technology and systems. We and the people they work with need to undertake their professional responsibility to be loyal to their job but also to serve their duty to the public, to protect the public welfare. Every single person has a role to fulfill and we as a team need to work together to achieve great things with human safety as our number one priority.

References:

1. 1Figure 1, Quora, What specific type of rubber was the Space Shuttle SRB O-rings made out of? What changes were made to them after Challenger? (https://www.quora.com/What-specific-type-of-rubber-were-the-Space-Shuttle-SRB-O-rings-made-out-of-What-changes-were-made-to-them-after-Challenger) [Accessed 21/10/20]
2. Figure 2, Bookdown, 5.1 Case Study: The Challenger disaster (https://bookdown.org/egarpor/PM-UC3M/glm-challenger.html) [Accessed 21/10/20]
3. Lewis, Richard S.Challenger: The Final Voyage. New York: Columbia University Press, 1988.
4. FAA, Legislation & Policies, Regulations & Guidance (https://www.faa.gov/space/legislation_regulation_guidance/) [Accessed 21/10/20]
5. NASA Fandom, Roger Boisjoly, Later career (https://nasa.fandom.com/wiki/Roger_Boisjoly)