Allan McDonald, Who Refused to Approve Launch of Ill-Fated Challenger Space Shuttle, Dies at 83

"I made the smartest decision I ever made in my lifetime," Allan McDonald told NPR of not approving the Challenger for launch, before his boss relented under pressure from NASA

Allan McDonald
Photo: Sean Smith/NASA

Allan McDonald, an engineer who refused to approve rocket boosters that were used in the Challenger space shuttle, has died at 83 after falling and injuring his head, according to NPR.

It was in 1986 that McDonald, who worked at NASA contractor Morton Thiokol, refused to sign off on the launch of the Challenger space shuttle at the Kennedy Space Center in Florida on Jan. 28 of that year. His reasoning, according to a Los Angeles Times, was because he believed the cold temperatures around launch day could affect the rocket booster's O-rings, which keep gases from escaping.

McDonald — working for the NASA contractor, Morton Thiokol — alerted the space agency's officials to the potential problem, with Thiokol recommending a delay to the launch, the outlet reported.

But NASA was not moved by McDonald's warnings and insisted on moving forward with the launch. McDonald refused to sign the necessary paperwork to approve the launch, with his boss doing so instead while under pressure from NASA.

"I made the smartest decision I ever made in my lifetime," he previously told NPR reporter Howard Berkes.

Allan McDonald

"I refused to sign it," McDonald said. "I just thought we were taking risks we shouldn't be taking."

Along with the O-ring problem, McDonald also raised concerns about ice on the launchpad that could damage the spacecraft and rough seas at the location where the booster rocket was supposed to be recovered.

"I said, 'Let me tell you something. I sure hope nothing happens tomorrow, but if it does, I am not going to be the person to stand in front of a board of inquiry and explain why I gave you permission to fly my rocket boosters in an environment I knew they would never qualify to fly in,'" McDonald recalled telling officials ahead of the ill-fated flight.

Seven astronauts would board Challenger on Jan. 28, 1986, taking off at 11:38 a.m. ET. The launch appeared to be going as expected until 73 seconds into the flight, when the shuttle exploded, killing everyone inside the spacecraft.

An investigative commission later said the accident was caused "by a failure in the joint between the two lower segments of the right Solid Rocket Motor," and recommended a redesign of the Solid Rocket Motor joint and seal.

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During a hearing following the accident, McDonald stood up in the audience and revealed he had warned NASA about the chance of disaster, NPR reported.

Morton Thiokol executives initially demoted McDonald for speaking publicly about the incident, but later promoted him and tasked him with redesigning the booster rocket joints. He'd continue to work with the company until 2001 when he retired.

He'd later pen the book, Truth, Lies, and O-Rings: Inside the Space Shuttle Challenger Disaster, and was featured in the Netflix documentary, Challenger: The Final Flight.

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