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Space

Challenger Accident

On the morning of 28 January 1986, the Space Shuttle Challenger, mission 51-L, rose into the cold blue sky over the Cape. To exuberant spectators and breathless flight controllers, the launch appeared normal. Within 73 seconds after liftoff, however, the external tank ruptured, its liquid fuel exploded, and Challenger broke apart. Stunned spectators saw the explosion and the trails from the spiral flights of the solid rocket boosters, but the vapor cloud obscured how the orbiter shattered into large pieces. The crew cabin remained intact, trailing wires and plummeting to the Atlantic; the six astronauts and one school teacher aboard perished.

Over the next three months, a presidential commission led by former Secretary of State William P. Rogers and a NASA team investigated the accident. Television images of the flight revealed an anomalous flame from a joint between segments of the right-hand solid rocket motor. Photographs showed puffs of black smoke escaping from the joint during the first moments of ignition. Wreckage of the motor recovered from the Atlantic floor demonstrated the failure of the joint and proved that propulsion gases had melted surrounding metals and caused the explosion of the external tank.

Propulsion engineers from Morton- Thiokol Incorporated, the Utah company responsible for the solid rocket motors, testified that for years they had been discussing problems with the joints and their O-ring seals, especially in cold weather. The night before the launch they had warned Marshall officials that the anticipated cold weather could freeze the rubber O-rings and trigger disaster, but company executives and Marshall project managers had rejected calls for a launch delay.

The Rogers Commission concluded that managers at Marshall and Thiokol had known (or should have known) that the case joints were hazardous. They had failed to inform senior officials in the Shuttle program or to act promptly to reduce risks, and thus had failed to prevent a predictable accident. The commission decided that since Marshall officials had prior knowledge of the hazard, the accident primarily resulted from ineffective communications and management at the Center.

The commission's interpretation has dominated discourse about Challenger. Journalists and academics have relied on the commission's evidence, and have mainly added analysis to confirm its "bad communication" thesis. "Instant histories" often treated the scenarios in the Rogers Report as quasi-crimes, with journalist-authors reporting dirty deeds in the Shuttle program and telling scabrous stories about NASA officials with "the wrong stuff."

Unfortunately, the commission's interpretation oversimplified complex events. The oversimplifications emerged mainly because the commission and later pundits dismissed the testimony of Marshall engineers and managers and distorted information about hazards in written sources from the Shuttle program prior to the accident. Allowing Marshall engineers and managers to tell their story, based on pre-accident documents and on post-accident testimony and interviews, leads to a more realistic account of the events leading up to the accident than that found in the previous studies.

The story of the Marshall engineers and managers was that they had carefully studied the problems of the motor case joints and had concluded that the joints were not hazardous, that they had taken steps to improve the joints, and that they had communicated their conclusions and actions to superior Shuttle officials. Because they believed the joints were not hazardous, they did not predict the accident and could not have prevented it.

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