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The Challenger: An Avoidable Tragedy : 24 Hours Of Pre-launch Debate

June 10, 1986

Officials of the National Aeronautics and Space Administration and executives and engineers of Morton Thiokol Inc., which built the space shuttle's solid rocket boosters, spent much of the 24 hours before the Jan. 28 launching debating whether cold weather would interfere with the functioning of the boosters' all-important O-rings. Here is the account of those discussions, as chronicled by the presidential commission on the Challenger disaster.


Jesse W. Moore, associate administrator for space flight, NASA headquarters.

William Lucas, director of the Marshall Space Flight Center, Huntsville, Ala.

Stanley Reinartz, manager of the shuttle projects office, Marshall Center.

Lawrence B. Mulloy, manager of solid rocket booster project, Marshall Center.

Cecil Houston, the Marshall Center's resident manager at the Kennedy Space Center in Florida.

Judson A. Lovingood, deputy manager of the shuttle projects office, Marshall Center.

Jim Kingsbury, director of science and engineering, Marshall Center.

George B. Hardy, deputy director of science and engineering, Marshall Center.

Arnold D. Aldrich, manager of the space transportation systems program, Johnson Space Center in Houston.


Jerald E. Mason, senior vice president, in Utah.

Calvin Wiggins, vice president and general manager of space division, Utah.

Joe C. Kilminster, vice president of space booster programs, Utah.

Robert K. Lund, vice president of engineering, Utah.

Roger Boisjoly, seal task force engineer, Utah.

Arnold Thompson, supervisor of rocket motor cases, Utah.

Robert Ebeling, manager of ignition system and final assembly, Utah.

Allan J. McDonald, director of solid rocket motor project, Kennedy Center.


1 P.M. (all times EST)--Minutes after scrubbing Challenger's launching because of wind conditions, NASA resets it for 9:38 a.m. Jan. 28. NASA asks Morton Thiokol if the company is concerned about cold temperatures predicted overnight at the launching pad. Thiokol's Ebeling is contacted in Utah to prepare an engineering evaluation.

2 P.M.--In a management team meeting, expected launch-time temperatures are discussed by Lucas, Moore, Aldrich and Mulloy.

2:30 P.M.--In Utah, Ebeling informs Boisjoly and other Morton Thiokol engineers about cold temperatures at Cape Canaveral.

4 P.M.--At the Kennedy Center, McDonald receives phone call from Ebeling expressing concerns from Morton Thiokol engineers about the effects of cold temperatures on rocket booster seals. McDonald asks the engineers to prepare for a telephone conference with NASA officials and then contacts Cecil Houston to make the arrangements, for the first time informing a Marshall Center official of Morton Thiokol's alarm over temperatures.

5:45 P.M.--In the first teleconference, Reinartz at the Kennedy Center and Lovingood at the Marshall Center hear Morton Thiokol officials in Utah recommend that launching be delayed until noon or later because of concern that cold morning temperatures might hurt O-ring performance. A second conference is set for 8:15 p.m. to discuss data with a larger number of managers and engineers.

6:30 P.M.--In a call to Reinartz, Lovingood says the launching should be postponed if Morton Thiokol's objections persist.

7 P.M.--Reinartz and Mulloy visit Lucas and Kingsbury in their Kennedy Center motel rooms to inform them of Morton Thiokol concerns and the plans for a second teleconference.

8:45 P.M.--From Utah, four Morton Thiokol vice presidents and 10 engineers participate in the second teleconference. Lund presents the engineering data and recommends no launching below 53 degrees. On the line from Marshall Center with Lovingood and others is Hardy, who tells Morton Thiokol he is "appalled" by the recommendation to delay.

At the Kennedy Center, Mulloy challenges the credibility of the data and the conclusions of Morton Thiokol's engineers, who recall Mulloy's saying, "My God, when do you want me to launch--April?"

In Utah, Kilminster asks to go off-line for five minutes so that company engineers can discuss their recommendation privately.

10:30 P.M.--The subsequent caucus is an emotional one. Referring to the charts and drawing their own crude diagrams, Thompson and Boisjoly voice strong objections to a launching. It is the unanimous position of all 10 engineers. Lund is also reluctant to launch. Mason tells Lund to take off his engineering hat and put on his management hat. Mason, Kilminster, Wiggins and Lund then vote to approve a launching.

Meanwhile, at the Kennedy Center, McDonald argues with Reinartz and Mulloy that the launching should be delayed.

11 P.M.--When the teleconference is resumed, Kilminster reports that Morton Thiokol has reassessed its recommendation and determined that the data on the effects of cold is inconclusive. Morton Thiokol now recommends launching. Hardy asks that the rationale for launching be put in writing and telefaxed to the Kennedy and Marshall centers.

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