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This case study of good practice in learning and teaching in materials features the Space Shuttle Challenger Disaster. It examines the technical (materials and design), political, and management factors contributing to the disaster.

Author: Dr Claire Davis

Institution: University of Birmingham

Abstract: The case study uses a variety of presentation methods (video, mini-lectures, role play) to illustrate the technical, political, management, educational and social effects of the Challenger disaster. Final report is an article in the style of a popular science magazine (e.g. New Scientist / Materials World) with the students selecting their approach.

Background to the introduction of the case study

The Space Shuttle Challenger disaster case study is an undergraduate activity that takes place at the start of the first term in the students first year. The case study is used to explore the role of engineering (in particular materials engineering) on the technical fault as well as the other, non-technical influencing factors on the failure causing the disaster and its effect on society. The aim is to engage the students with a real problem early in their university studies to increase their understanding of, and motivation in, the subject. Student motivation can be a problem in materials engineering courses as some students entering the course may not fully appreciate what the subject entails (not having studied it at school), some students may not have selected materials engineering as their first choice subject, and some students may not be highly motivated to academic study.

In 1997 it was recognised that the first year of our materials engineering course at the University of Birmingham contains many modules dealing with theoretical concepts and basic materials content, both of which are important to the subject. However, students only see the relevance of this later in the course when they use the concepts and build upon the knowledge when dealing with real problems such as failure and artefact analyses. It was felt that if examples (in the form of case studies) could be introduced early into the course then the students would gain an appreciation of why they need to learn the theoretical concepts and therefore this would increase their motivation. As a consequence three case studies were introduced into our course of which the Space Shuttle Challenger disaster is the first in the series.

Case study style

The case study is a class activity that is assessed through an individual report. The case study uses a variety of techniques to present information (technical, economic and social) and is designed to engage the students in the learning process. Technical information is presented using a NASA video, mini-lectures and handout sheets. Role-play is used where volunteer students act out a scenario (according to a set script) that occurred during the Challenger pre-launch period. The class is required to 'interview' technical experts following a mini-lecture on topics including the political history of the space programme, the impact on society of the teacher in space programme and the technical cause of the failure (i.e. rubber o-ring performance, rocket booster design). The time-tabled activities take place during a single 3 hour period with an additional week allowed for independent learning and the write up of the report.

Case study structure

The case study uses a variety of presentation methods to expose the students to the technical, political, management and social affects of the Challenger disaster. The students are then asked to write an article in the style of a popular science magazine (for example New Scientist / Materials World) considering one aspect of the overall problem. The students are given handouts containing technical information regarding the solid rocket fuel booster (SRB) joint design and the shuttle programme history, including previous tests and incidents linked to the cause of the Challenger disaster. Video footage (provided by NASA) is used of the pre-flight procedure, the flight sequence (including shuttle break up) and post flight analysis. Mini-lectures and 'interviews' with experts (other lecturers in the School of Metallurgy and Materials) are used to illustrate the varying factors that influenced the decision to launch and the final failure. The students are briefed that they are to interview experts in a specific area who are only available for 10-15 minutes. The students are given a short introduction to the expert's area then some time to consider what questions they wish to ask. My role during this period is to facilitate the question and answer session and to introduce the experts. The interviews cover rubber technology, space flight history, NASA politics and social issues (effect of role models on society). Role play of a telephone conversation prior to launch between the NASA management and technical experts from Mortoon Thiokol (the manufacturers of the SRB's) is also used. The students are encouraged to participate at all stages of the case study.

The students are given example articles from Materials World (on other topics) as guidelines for the required technical level and format of their report. They are also encouraged to carry out further research (for example on alternate materials suitable for use as o-rings under the conditions experienced in the SRB and / or design changes that Morton Thiokol have introduced, NASA policy changes, personal views from employers at NASA and Morton Thiokol etc.) using the internet and / or texts (references are provided) before submitting their reports.

Learning outcomes

At the end of the case study the student will be able to:

  • present information to an appropriate level and format as demonstrated by a report in the style of a popular science article
  • explain how the Space Shuttle Challenger disaster resulted from a number of different factors
  • describe how rubber has different mechanical properties at different temperatures
  • explain how increased engineering knowledge has led to improvements in Space Shuttle safety

Relevance to materials engineering

The technical cause of the disaster was the leak (blow-by) of fuel from one of the SRB joints resulting in rupture of the external fuel tank and shuttle break up. The leak was caused by rubber o-rings not completely sealing the SRB joint as the abnormally low temperatures experienced at the launch site affected the materials properties (making the rubber less resilient to structural vibrations). During the case study the students are presented with data on a variety of rubbers illustrating how their resilience is affected by temperature, in addition a demonstration is used to illustrate the property of resilience. Information is also presented on high temperature rubber performance and the materials costs. Comparisons are made with the properties required by rubber o-ring seals in other applications, for example automotive applications to show that whilst there are similarities between different applications each must be considered individually to ensure the optimum material is selected. The video used highlights the influence of mechanical design of the SRB joint on the failure through the flexing of the joints that, combined with the low temperatures and reduced resilience of the rubber o-rings, resulted in the fuel leak. Data on the previous cases of blow-by and engineering tests on the joint carried out by Morton Thiokol are given to the students. The students are also encouraged to carry out additional research into the materials and design changes that have been implemented by NASA following the Challenger disaster.

The case study also examines the role of engineers in the management process providing an example of management issues early in the undergraduate course. The unusually low temperatures experienced in Florida at the time of launch prompted a telephone conversation between NASA officials and engineers and managers at Morton Thiokol. The scripted role play exercise examines the conflict between the engineers considering the safety risks of launching the shuttle in conditions (i.e. temperatures) they had not anticipated or tested for and the managers considering the financial implications of a further delay to launch or how to justify any new safety constraints on launch to the NASA officials.


Student feedback

Informal student feedback, via personal tutorials and the staff student liaison committee, has indicated that the students enjoy the case study. One student commented that 'the case study has helped demonstrate the relevance of the other courses I am studying'. No formal assessment of student perception or the success of the learning outcomes compared to other learning styles has been carried out.


Further plans for development

The case study currently relies on being able to timetable all contributing staff in the same teaching period. It is hoped that the specific knowledge of the individuals acting as 'experts' can be collated to allow alternate presentation methods (e.g. video, CD-ROM etc.) or cover by other members of staff if needed / as appropriate.


References


  

 

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