Causes of the 1986 Space Shuttle

Challenger Disaster

Ci Sian Lim509424

The Incident 28th January 1986 (Bruno 1994, p. 609) Cape Canaveral, Florida, USA (Bruno 1994, p. 610) An explosion of the shuttle occurred 73 seconds after launch (Bruno 1994, p. 609)

Weather on day of launch was freezing cold (Bruno 1994, p. 609)

Failure of the aft field joint of the Solid Rocket Booster triggered the structural disintegration (Bruno 1994, p. 609)

Bruno, LC 1994, ‘Challenger explosion (1986)’, in N Schlager (ed.), When technology fails: significant technological disasters, accidents and failures of the twentieth century, Gale Research, Detroit, pp. 609 – 616.

The Causes Design Flaws

•Conditions of Solid Rocket Boosters•Putty Compound •The O-rings

Mismanagement• Prioritization issues•Miscommunication between NASA and Thiokol management

•Compromising safety

Solid Rocket Boosters’ joint segments

The gap between the tang and clevis to was irregular at assembly. (Presidential Commission on the Space Shuttle Challenger Accident 1986, p. 70).

The diameters of the segments of the Solid Rocket Motors had grown due to prior use (Presidential Commission on the Space Shuttle Challenger Accident 1986, p. 70).

The irregular size of the tang and clevis gap caused the O-rings to compress and to fully occupy the compartment (Presidential Commission on the Space Shuttle Challenger Accident 1986, p. 70).

No space for pressure to actuate the O-rings (Presidential Commission on the Space Shuttle Challenger Accident 1986, p. 70).

Presidential Commission on the Space Shuttle Challenger Accident 1986, Report of the Presidential Commission on the Space Shuttle Accident, (WP Rogers, Chairman), Presidential Commission on the Space Shuttle Challenger Accident, Washington DC, viewed 21 February 2014, http://history.nasa.gov/rogersrep/genindex.htm

Putty Compound Motor pressure should be applied to actuate the O-ring and seal the joint but evidence indicates that ‘temperature, humidity and other variables in the putty compound can delay pressure application to the joint’ immediately after ignition. (Presidential Commission on the Space Shuttle Challenger Accident 1986, p. 70)

The delay in pressure led to the O-ring not sealing the joint. (Presidential Commission on the Space Shuttle Challenger Accident 1986, p. 70)

‘Beforehand erosion and O-ring thermal distress was accompanied by a leak path in the insulating putty’ (Presidential Commission on the Space Shuttle Challenger Accident 1986, p. 70).

Causing the combustion gases getting in contact with the O-ring region of tang and clevis. (Presidential Commission on the Space Shuttle Challenger Accident 1986, p. 70)

The O-rings The O-rings are made of rubber and is used as a seal in the gap between the tang and clevis in the Solid Rocket Booster. (Presidential Commission on the Space Shuttle Challenger Accident 1986, p. 70

Due to freezing cold weather, the O-rings’ resiliency was reduced and was malfunctioning as seal on the day of launch. (Presidential Commission on the Space Shuttle Challenger Accident 1986, p. 70

As there was soot found in the O-ring region, evidence states that parts of the O-ring was eroded away by combustion gases in prior flights. Even if the gap between the tang and clevis was not widened, the O-ring was unable to seal the gap. (Lighthall 1991, p. 64)

Lighthall, F 1991, ‘Launching the Space Shuttle Challenger: Disciplinary Deficiencies in the Analysis of Engineering Data’, IEEE Transactions On Engineering Management, vol. 38, no. 1, p. 63 – 74.

Figure 1 shows the distribution of O-ring temperatures for NASA flights adapted from Lighthall 1991, p. 68.

Prioritization Issues During preparation of launch, safety was placed second as productivity was the first priority. Due to the Space Race happening between the European Space Center and the US Government, there was pressure pushed onto NASA. (Altabbakh, Murray, Grantham & Damle 2013, p. 14)

Constraints were put onto their timeframe of launches which then led to the state where delays are unacceptable. (Bruno 1994, p. 609)

Budget was also a more important priority than safety. It affected the safety assurance by not investing in O-ring anomalies investigation testing which led to inadequate testing of the O-rings. (Altabbakh, Murray, Grantham & Damle 2013, p. 14)Altabbakh, H, Murray, S, Grantham, K & Damle, S 2013, ‘Variations in Risk Management Models: A Comparative Study of the Space Shuttle Challenger Disaster’, Engineering Management Journal, vol. 25, no. 2, pp. 13 – 25.

Prioritization Issues NASA was under political pressure which led to tight scheduling and following their schedule with no exceptions due to the fact that a teacher was sent to space as an astronaut. (Altabbakh, Murray, Grantham & Damle 2013, p. 14)

NASA was also under public pressure as this is a first for the US and if it fails, the reputation of NASA and the US government would be affected. (Bruno 1994, p. 609)

Bruno, LC 1994, ‘Challenger explosion (1986)’, in N Schlager (ed.), When technology fails: significant technological disasters, accidents and failures of the twentieth century, Gale Research, Detroit, pp. 609 – 616.

Safety•Risk assessment………………………..•Inadequate testing

Miscommunication NASA unaware of the Morton Thiokol’s engineers’ objections to launch:• The anomalies regarding the O-ring remaining ‘in-house’ on NASA Level III management (Morton Thiokol, a NASA contractor) is due to ‘fear of job loss’ and was reluctant to deliver the bad news to NASA. (Saussois & Laroche 1991, p. 104)

• Morton Thiokol managers had their own perspective of overruling their own engineers stating that they had not enough data to convince them of the O-ring issue. Which is where the gap between levels in NASA occurred. (Altabbakh, Murray, Grantham & Damle 2013, p. 14)

Failing to notice the seriousness of the problem

Saussois, J & Laroche, H 1991, ‘The Politics of Labelling Organizational Problems: An Analysis of the Challenger Case’, Knowledge and Policy: The International Journal of Knowledge Transfer, vol. 4, no. 1 and 2, pp. 89-106.

Bruno, LC 1994, ‘Challenger explosion (1986)’, in N Schlager (ed.), When technology fails: significant technological disasters, accidents and failures of the twentieth century, Gale Research, Detroit, pp. 609 – 616.

SummaryDesign Flaws: • O-rings

• Weather conditions

• Erosion• Putty compound

• Delay in pressure

• Segments• Out-of-round conditions

Mismanagement:• Prioritization

• Productivity and reputation

• Safety issues• Competition• Budget

• Poor communication• Fear of job loss

Reference listAltabbakh, H, Murray, S, Grantham, K & Damle, S 2013, ‘Variations in risk management models: a comparative study of the Space Shuttle Challenger disaster’, Engineering Management Journal, vol. 25, no. 2, pp. 13 – 24.Bruno, LC 1994, ‘Challenger explosion (1986)’, in N Schlager (ed.), When technology fails: significant technological disasters, accidents and failures of the twentieth century, Gale Research, Detroit, pp. 609 – 616.Lighthall, F 1991, ‘Launching the Space Shuttle Challenger: disciplinary deficiencies in the analysis of engineering data’, IEEE Transactions On Engineering Management, vol. 38, no. 1, pp. 63 – 74.Saussois, J & Laroche, H 1991, ‘The politics of labelling organizational problems: an analysis of the Challenger case’, Knowledge and Policy: The International Journal of Knowledge Transfer, vol. 4, no. 1 and 2, pp. 89-106.

Reference listPresidential Commission on the Space Shuttle Challenger Accident 1986, Report of the Presidential Commission on the Space Shuttle Accident, (WP Rogers, Chairman), Presidential Commission on the Space Shuttle Challenger Accident, Washington DC, viewed 21 February 2014, http://history.nasa.gov/rogersrep/genindex.htm