Whistleblower in Challenger shuttle disaster dies at 83

Allan Mcdonald, a rocket scientist and whistleblower who refused to sign off on the space shuttle Challenger’s launch over safety concerns and, after its explosion, argued that the tragedy could have been averted had officials heeded warnings from engineers like himself, died March 6 at a hospital in Ogden, Utah. He was 83.

The cause was complications from a recent fall, said his daughter Lora Mcdonald.

For the millions of Americans who turned on their television sets to watch the Challenger take off on Jan. 28, 1986, the image of the space shuttle blowing apart in midair - killing seven astronauts, including New Hampshire schoolteacher Christa Mcauliffe - was seared into their memory. The disaster is often described as an event on the order of the assassination of President John F. Kennedy in 1963 or the terrorist attacks of Sept. 11, 2001: Those who lived through it will never forget where they were when it occurred.

Mcdonald was in Cape Canaveral, Fla., at NASA’S Kennedy Space Center, where the Challenger was set to take off. He was the senior on-site representative of his company, contractor Morton Thiokol, where he oversaw the engineering of the rocket boosters used to propel the shuttle into space. Among colleagues, the New York Times reported, Mcdonald had a reputation as one of the most skilled rocket engineers in the country.

It was unseasonably cold in Florida, with weather forecasts predicting that temperatures might drop as low as 18 degrees Fahrenheit in the hours before the Challenger was scheduled to lift off. That cold snap became the crux of vociferous debate among Mcdonald and other engineers, Morton Thiokol executives and NASA officials about whether the mission should go forward.

Citing the cold, Mcdonald insisted that takeoff be postponed, according to accounts of the deliberations that later emerged in news reports. A critical component of the rocket booster was the O-ring, a rubber gasket that served to contain burning fuel. Because of their composition, Orings were highly vulnerable to temperature drops, and engineers warned that their effectiveness could not be guaranteed below 53 degrees Fahrenheit.

Mcdonald relayed these concerns in what he described as increasingly frenzied conversations the night before the launch. NASA officials, upset by the last-minute complication, were eager to move forward with the mission; company executives, according to later findings by a presidential commission on the Challenger disaster, appeared to feel pressure to “accommodate a major customer.”

In addition to the matter of the O-rings, Mcdonald said he raised weatherrelated concerns including the danger that ice might damage the shuttle’s exterior.

“If anything happened to this launch, I told them I sure wouldn’t want to be the person that had to stand in front of a board of inquiry to explain why I launched this outside of the qualification of the solid rocket motor,” he would later testify.

Protocol required the senior engineer to sign off on the launch. When Mcdonald refused, his supervisor signed for him. The Challenger lifted off at 11:38 a.m. on Jan. 28 and disintegrated approximately 72 seconds later, its remains streaking across the sky.