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Challenger Memorandum

The memorandum recommends delaying the launch of the space shuttle Challenger due to safety concerns with the O-rings at low temperatures. Data from previous shuttle launches showed damage to the O-rings when temperatures were below 66°F, and a test of backup rings failed to reseal at 50°F. If damaged, the O-rings may fail to contain hot gases and cause complications. The forecast for the Challenger launch was 26-29°F, so proceeding could result in catastrophe and loss of life. The memo urges delaying the launch until temperatures reach at least 66°F to avoid disaster.

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143 views3 pages

Challenger Memorandum

The memorandum recommends delaying the launch of the space shuttle Challenger due to safety concerns with the O-rings at low temperatures. Data from previous shuttle launches showed damage to the O-rings when temperatures were below 66°F, and a test of backup rings failed to reseal at 50°F. If damaged, the O-rings may fail to contain hot gases and cause complications. The forecast for the Challenger launch was 26-29°F, so proceeding could result in catastrophe and loss of life. The memo urges delaying the launch until temperatures reach at least 66°F to avoid disaster.

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MEMORANDUM

Luke Schwarz
Engineering Department
Morton Thiokol Inc.
2475 Washington Blvd.
Ogden, Utah 84401
(801) 629-2270

December 27, 1985

Todd May
Director of Marshall Space Flight Center
Marshall Space Flight Center
Huntsville, AL 35811
(256)-544-2121

Subject: ​Delaying the launch of the Challenger shuttle.

Problem:​ We strongly recommend that the launch of the Challenger shuttle be delayed.
Launches at lower temperatures have a tendency to sustain more damage to the O-rings. With
the temperature being forecasted at about 26-29 °F, launching the shuttle will result in a
catastrophic failure and likely loss of life.

Details: ​Data from previous shuttle launches shows that all shuttles launched at temperatures
lower than 66 °F suffered some level of O-ring erosion. The O-rings are made to seal under the
pressure of the gases, but they don’t always perform as intended in colder weather. A test on
secondary O-rings showed that “At 100 °F the o-ring maintained contact. At 75 °F the o-ring lost
contact for 2.4 seconds. At 50 °F the o-ring did not re-establish contact in ten minutes at which
time the test was terminated” (Winsor 1988). If the O-rings obtain too much erosion damage and
the secondary O-rings fail to make contact quick enough hot gases will leak from the SRB and
cause massive complications putting the shuttle and its passengers at risk.

Solution: ​It is crucial that the launch of the Challenger shuttle be delayed until the temperature
is at least 66 °F in order to avoid a major disaster resulting in the loss of the Challenger shuttle
and it’s passengers.
Key
= Forecasted Temperature Of The Challenger Launch (26-29 ​°F)

= Predicted Damage To The Challenger’s O-rings

= Shuttle Launches
= Trend Line
Damage Index = A system created by Tufte which is used to illustrate the severity of the
damage the O-rings insured. The score given to each launch is based upon O-ring erosion,
Heating, and blow-by which are weighted differently based upon their impact on the rocket’s
function (Tufte 1997).
References

Tufte, E. R. (1997). ​Visual and statistical thinking: Displays of evidence for making decisions ;
displays of evidence for making decisions​. Graphics Pr.

Winsor, D. (1988). Communication failures contributing to the Challenger accident: An example


for technical communicators. ​IEEE Transactions on Professional Communication,31​(3),
101-107. doi:10.1109/47.7814

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