The 40th Anniversary of Challenger

A lesson in ethics.

By Ed Butts, PE, CPI

Figure 1. Space shuttle configuration.

As I look back at my columns in recent years, I realize I have primarily concentrated on the “Engineering” part of the column title and somewhat ignored the “Business” aspect. I’m going to attempt to correct that this year by focusing on business-related topics such as project bidding, estimating, asset management, and business and professional ethics.

As a kickoff to this plan, I want to begin with a column on ethics and the 40th anniversary of the Challenger space shuttle disaster that occurred on January 28, 1986.

While most of us will never face the decisions and life-altering mistakes cited in this column, I believe we can all learn from the past errors of others and apply the corrections to our own worlds.

The possibility of failure is an interesting impediment to progress. If we all had a constant fear of failure, which is known as atychiphobia, our society would have never tried or succeeded in so many technological advancements.

The potential for failure in space exploration is a given. Many will claim the Challenger event demonstrated a breakdown in engineering ethics. While I agree the proper observance of engineering ethics was certainly disregarded, I also feel the fundamental concept of business and personal ethics were violated as well.

Thus, we can all learn from this unfortunate event as a parallel to our work and personal interactions with its undeniable and obvious ethical lessons that are not easily ignored or forgotten. But before we get there, let’s start with some background.

The Space Shuttle

Figure 2. Challenger crew and mission patch.

The space shuttle was the first operational orbital spacecraft designed and constructed specifically for return from space and subsequent reuse. Five complete space shuttle orbiter vehicles were built, including the original Constitution, later renamed Enterprise, and four operational vehicles: Discovery, Atlantis, Columbia, and Challenger.

They flew on a total of 135 missions between 1981 and 2011. The shuttle program was initially planned for 24 missions per year while each orbiter was designed for a projected lifespan of 100 launches or 10 years of operational life, and this was later extended.

At launch, the assembly (Figure 1) consisted of the orbiter, which contained the crew and payload bays, and the external fuel tank, which housed liquid oxygen as an oxidizer and liquid hydrogen for fuel in separate vessels. This tank delivered fuel to three main liquid-fed engines on the orbiter, along with the two attached solid rocket boosters. The two SRBs were designed and built by Morton Thiokol Inc.

The Challenger Mission Background

Figure 3a. Challenger launch.

The year 1986 was shaping up to be the most ambitious year yet for NASA’s space shuttle program. The agency’s plans called for up to 15 missions, translating to over one per month, on average. This included the first flight from the West Coast launch site at Vandenberg Air Force Base in California. Other important missions included the launch of two planetary spacecraft with tight launch windows: an astronomy mission
to study the 75- to 79-year expected return of Halley’s Comet, and the launch of the Hubble space telescope.

The first mission of 1986, STS-61C, delayed from December 1985, flew between January 12-18. The next flight, designated STS-51L, marked the 25th flight in the shuttle program and the 10th for space shuttle Challenger.

The mission was to be aggressive as during the six-day mission the seven-member crew (Figure 2) was to deploy a large communications satellite, deploy and retrieve an astronomy payload to study Halley’s Comet, and have the first teacher in space who would conduct lessons for schoolchildren from orbit.

Figure 3b. Visible flame from O-ring joint onto fuel tank.

The Challenger crew would deploy the Spartan-Halley observer on the third mission day and retrieve it two days later after it completed its observations. The teacher in space activities by Christa McAuliffe were to consist of two live sessions planned for the mission’s sixth day. Several other lessons to describe physical phenomena in weightlessness were to be filmed for later distribution.

Workers at NASA’s Kennedy Space Center (KSC) began preparing Challenger for its STS-51L mission immediately after it returned from its previous mission, STS-61A. After its arrival back at KSC on November 11, 1985, they towed Challenger into the Orbiter Processing Facility to remove the Spacelab module from the payload bay and to begin refurbishing the orbiter.

Challenger was towed to the Vehicle Assembly Building on December 16 to attach it to its external tank and solid rocket boosters. The rollout to Launch Pad 39B then occurred on December 22. With space shuttle Columbia already occupying Launch Pad 39A, awaiting its delayed launch on the STS-61C mission, this marked the first time that a shuttle occupied both launch pads.

After the successful conclusion of a simulated launch, managers targeted January 23 as the launch date, but this ultimately slipped to January 26 due to continued delays with STS-61C. The astronauts thereafter traveled from Houston to KSC on January 24. With unfavorable weather projected for January 26, managers delayed the launch by one additional day to January 27. The crew boarded Challenger for their first launch attempt, but managers subsequently scrubbed the launch, first due to a mechanical issue and then because winds at KSC violated established launch constraints.

The Launch

Figure 3c. Challenger explosion and release of two solid rocket boosters.

The astronauts once again boarded Challenger on January 28 as NASA managers cleared the launch to occur despite unexpectedly cold temperatures, down to 18°F, occurring overnight at the launch site. NASA managers decided significant ice observed covering parts of the launch tower was not enough of a concern to further delay the launch.

In behind-the-scenes discussions, concerns by Thiokol engineers about the effects the cold temperatures had on the integrity of the O-rings in the SRB segment joints were expressed but overruled by NASA managers who again cleared Challenger to launch.

Liftoff took place at 11:38 a.m. (Figure 3a). As soon as Challenger cleared the launch tower, control of the vehicle transferred from KSC’s Launch Control Center to the Mission Control Center in Houston Texas, where the flight director and his team monitored the mission’s progress.

For the first minute or so, the ascent appeared to proceed normally, but a visible flame was observed by tracking cameras to be emanating from one of the SRB’s O-rings onto the fuel tank (Figure 3b). At 73 seconds following liftoff, the point of reaching maximum engine performance, controllers lost all telemetry transmissions from Challenger and simultaneously observed a fireball on their television monitors with the simultaneous release of the two SRBs (Figure 3c).

Stunned controllers slowly came to realize that the vehicle had suffered what was referred to as “obviously, a major malfunction,” and it was an explosion the crew likely could not survive. Recovery efforts immediately began, but it soon became apparent there was no hope for crew survival.

Findings and Aftermath

Figure 4a (left). Solid rocket booster O-ring joint construction. Figure 4b (right). Route of gas escape in O-ring joint.

A lengthy investigation of the accident conducted by the independent Rogers Commission revealed numerous safety and launch decision issues. Among the commission’s findings included a flawed evaluation and decision process for shuttle launches, with NASA managers not fully evaluating or appreciating the real dangers of launching a space shuttle in colder weather.

The ultimate technical cause was determined to be erosion of the O-rings followed by propellant gas bypass through the SRB seals. The sealed joints are intended to prevent hot gases from leaking past the field joint during the propellant burn of the solid rocket booster (Figure 4a). This gas bypass directed a direct burning flame onto a strut securing the SRB to the assembly (Figure 4b).

Once free, the SRB swung into the external fuel tank, resulting in a rupture and massive explosion of the tank and release of the orbiter and SRBs. Portions of the shuttle diverted in different directions, with the SRBs temporarily remaining in flight until the propellant was exhausted. All components of Challenger eventually crashed into the Atlantic Ocean.

Lessons Learned

Most engineers normally realize and concur that uncertainty in engineering design and practice is almost always expected, inescapable, and often unforeseen, despite recent advancements in many aids and technologies such as computer aided design (CAD) and system computer modeling techniques.

However, although the events of January 1986 were ultimately exposed to much more public scrutiny, the lessons learned are as apparent as a first-year engineering ethics and management course could offer. The size and scope of the project does not matter and cannot change the underlying need to continually observe and practice appropriate ethics during the design and construction process, especially when life safety is involved.

The increasing demand for engineers who design products and systems is constantly placing added pressure on adhering to engineering standards as well as the engineer’s own integrity, particularly considering the decreased time often allowed for the design phase and proper vetting.

During the obligatory pre-flight meeting, several NASA and Morton Thiokol engineers vigorously debated the validity of launching the shuttle in such unusually cold weather. Despite repeated pleas and anecdotal evidence from several Thiokol engineers that the risk to crew and vehicle safety was too great and to postpone the launch, NASA overruled them and erroneously concluded that launching was an acceptable risk as the rubber-like O-rings would become sufficiently flexible and pliable at the temperatures experienced during flight to effectively seal the SRB joint segments. This unfortunately proved to be a fallacy that ultimately took the lives of the seven crew members.

Another overlooked consideration was the material quality used for the O-rings. The use of substandard, unvetted, or new materials with unpredictable and inadequately tested properties in manufacturing of products for the space shuttle breaches all reasonable engineering standards. If the space shuttle was ever planned or intended to launch in cold weather, the O-rings should have been manufactured, tested, and certified for those conditions, and they were not.

The design and engineering practices involved in the manufacture of the space shuttle Challenger were marred by numerous ethical, managerial, and moral lapses in judgement by both NASA and Morton Thiokol management.

It’s not as if NASA had not been warned. STS 41D (Discovery) experienced what is called “blowby” on a generally more robust factory-assembled nozzle joint in September 1984. This resulted in hot propellant gas flowing past the primary O-ring, requiring the secondary O-ring to seal, averting a probable disaster.

Later, on January 24, 1985, during the post-flight examination with STS-51C (Discovery), joint erosion and blowby were both discovered at a single field joint with erosion or blowby occurring in at least one joint in each SRB. The joint failures were determined to be caused by an unusually low launch temperature of just 53°F!

The O-ring failures were ultimately determined to be the cause of the Challenger disaster as a result of a loss of resilience at low temperatures, although severe lapses in proper management were equally to blame.

Unfortunately, NASA, a federal agency charged with ensuring professional engineering and high-quality control standards during space exploration are continually met, lowered or disregarded its own applicable launch rules meant for controlling real safety risks in exchange for adhering to an arbitrary launch schedule.

Morton Thiokol engineers seemed aware of these trade-offs but nonetheless allowed the individual and unrelated interests of Thiokol and NASA management to prevail even over the objections of their own engineers. During a pre-launch debate and teleconference call, under duress from NASA and being told to “take off your engineer hat and put on your manager hat,” Thiokol managers eventually signed off on the launch, leading to the disastrous consequences.

Following the Challenger incident, numerous design changes to the solid rocket boosters, including tighter launch rules and a completely different and improved joint design using three O-rings, allowed NASA to continue safely flying the solid rocket boosters without further serious issues.

The new joints and redundant O-rings were proven through rigorous development, validation testing and analysis, and demonstrated with the successful operation of over 200 solid rocket boosters. Following each launch and test, boosters were thoroughly inspected and joint performance verified. The NASA management hierarchy and launch decision process was also overhauled and improved.

The lessons learned from this event are universal in concept and cannot be overstated. Valid engineering and technical considerations, particularly those involving life-safety concerns, must always have precedence and priority over all non-technical or secondary issues such as meeting arbitrary schedules; possible embarrassment; client, employer, media, or public pressure; or adhering to a quote, budget, or program cost.

This should be a lesson to all engineers and other technical individuals that, when applicable, decisions must always be made with a critical eye and consideration towards the well-being and safety of everyone involved.

Although our daily activities in the water well industry are unlikely to ever rise to the risk and consequences associated with the Challenger disaster, we can nonetheless continue to strive for observance of ethical practices and individual excellence while fostering and promoting a safe work environment for ourselves, coworkers, and employees.

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We will continue our series on business practices next month with a topic more relevant to many of you: business management.

Until next month, work safe and smart.

Ed Butts, PE, CPI, is the chief engineer at 4B Engineering & Consulting, Salem, Oregon. He has more than 40 years of experience in the water well business, specializing in engineering and business management. He can be reached at epbpe@juno.com.