Materials: Shuttle Disasters and the importance of safety, teamwork , and effective action

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The Space Shuttle Challenger disaster occurred in the United States, on January 28, 1986. The Space Shuttle Challenger disintegrated 73 seconds into its flight after an O-ring seal in its right solid rocket booster (SRB) failed. The seal failure caused a flame leak from the solid rocket booster. Within seconds, the flame caused structural failure of the external tank.



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The shuttle was destroyed and all seven crew members were killed.

The night before the launch the Shuttle was exposed to low temperatures. During the investigation the famous physicist, Richard Feynman, was able to show that the O-rings lost flexibility when . As a result of loss of flexibility the O-rings could not perform the job they were for. Another important revelation by Richard Feynman was that the NASA management did not communicate effectively with engineers. Even worse, they did not act positively when the engineers expressed concern about the of the O-rings. The Management's estimates of safety factors were also poorly understood and incorrect. NASA managers recorded a safety factor of 3, based on some O-rings cracking one-third of the way through, during tests. This is an incorrect interpretation of safety factor. A safety factor of three means that the device could withstand three the amount of stress that the device would be subject to in practice.


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In another shuttle disaster, damage was caused during launch when a piece of foam insulation the size of a small laptop fell off the main propellant tank under the high experienced during launch.


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This is an image of a foam ramp. When the foam insulation fell off, it struck the leading edge of the left wing on a reinforced carbon-carbon tile. This damaged the Shuttle's thermal protection system. This protection was designed to withstand in excess of 2500 C on re-entry. While Columbia was still in orbit, some engineers suspected damage, but NASA managers did little to assist the engineers requests, and stated that little could be done even if problems were found. This action was criticised in the of the disaster.


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During re-entry, the damaged area of the wing allowed the hot gases to penetrate and destroy the internal wing structure. This resulted in the breakup and destruction of the vehicle. All crew members were killed.

Again, NASA management failed to recognize the importance of listening and acting upon the engineers' concerns for . The NASA did not follow up a number of requests from engineers to inspect possible damage using cameras. The managers did not respond to requests from engineers to request the to inspect the left wing.

These two disasters highlight the importance of everyone involved in a project to be aware and act upon issues. There are other potential disasters awaiting if engineers do not structures with sufficient safety factors built in. For example, allowance must be made for the expansion and contraction of materials when designing structures such as buildings, aircraft, and roads. If this is not done correctly, then the structures could when being used. Apart from damage to the structures, people could be hurt or .


A Shuttle design engineer must know the of the materials to be used when designing the vehicle. The engineer needs to know how the materials behave at high and low , and when large are applied to the structure. Allowance must be made for extreme conditions of weather. An understanding of the of materials when joined to other materials is essential if the design is going to be successful. It is also important that the safety features and limitations are understood by the of projects.



IN MEMORIAM
"The future is not free: the story of all human progress is one of a struggle against all odds. We learned again that this America, which Abraham Lincoln called the last, best hope of man on Earth, was built on heroism and noble sacrifice. It was built by men and women like our seven star voyagers, who answered a call beyond duty, who gave more than was expected or required and who gave it little thought of worldly reward."
- President Ronald Reagan January 31, 1986

(All images are Public Domain : NASA)