The Space Shuttle Challenger Disaster

“A safety engineer requires knowledge, tact and, at times, more than a little courage”
– An operating company management system.

Today marks the 39th anniversary of the Space Shuttle Challenger disaster, a painful reminder to the world that space travel is never routine.

Just Another Launch

On the 28th of January 1986, the Space Shuttle Challenger was scheduled to launch with the mission of deploying two American satellites into orbit. Challenger was the second of four space shuttles at the time and had already performed nine successful missions. This launch was to be the 25th space flight in the space shuttle programme. It was just another space shuttle launch. Lieutenant Colonel Dick Scobee, an experienced test pilot and astronaut, led a crew of five men and two women. Space shuttle flights had become so routine that one of the crew was a schoolteacher, Sharon Christa McAuliffe, who was due to conduct lessons from space for school children across America.

The Path to Failure

During the launch, the O-ring seal of the right Solid Rocket Booster (SRB) failed. According to the Presidential Commission, the low temperatures on the days leading to the launch had compromised the O-ring, affecting the joint rotation ability due to the reduced elastic properties and shrinkage. This led to a breach of the internal structure of the space shuttle.

This failure allowed pressurised hot gases to escape from the SRB, breaching the joint, impinging on the adjacent structures including an external hydrogen tank. The intense heat and pressure of the gas eroded the external tank, ultimately causing a fatal structural failure. Just 73 seconds after liftoff, at 11:38 a.m. EST, the Challenger disintegrated due to the explosion of the hydrogen tank, resulting in the loss of all seven crew members on board.

A case study by Charles E. Harris, Jr. examined the events leading up to the disaster. The study highlighted that the disaster was preceded by multiple launch delays and internal debate among engineers and managers at Morton Thiokol Corporation. Thiokol was the company contracted by NASA to build the SRB. Thiokol’s engineers had concerns that the low temperature conditions could result in potential failure in the O-rings. The engineers had compiled all the information and evidence into a one-hour presentation the night before the launch to highlight this problem to the managers. The Thiokol managers decided that the data was inconclusive, with a senior executive at Thiokol telling them to

“Take off your engineering hat and put on your management hat”

The Aftermath

That evening, just hours after the disaster, President Ronald Reagan reminded the world that space travel is not routine, when he addressed the American nation and said of the lost crew,

“…. we’ve never had a tragedy like this. And perhaps we’ve forgotten the courage it took for the crew of the shuttle…
We’ve grown used to the idea of space, and perhaps we forget that we’ve only just begun. We’re still pioneers. They, the members of the Challenger crew, were pioneers…
We will never forget them, nor the last time we saw them, this morning, as they prepared for their journey and waved goodbye and ‘slipped the surly bonds of earth’ to ‘touch the face of God.’ “

The Inquiry

A Presidential Commission into the Space Shuttle Challenger Accident was held, commencing hearings on 26 February 1986. The Presidential Commission report was delivered on 6 June 1986.

As well as nine key recommendations, it raised a critical question:

“Should the engineering concerns, as expressed in the pre-launch teleconference, have been sufficient to stop the launch?”

The Commission’s conclusion was “Yes” and explained that expert opinions should be considered in the absence of opposing evidence. Thiokol’s expert engineering team obtained data that they believed to be sufficient to support their claims. Despite this, Thiokol’s management did not heed their warnings, which was deemed a critical fault.

The Presidential Commission found that:

“Meeting flight schedules and cutting cost were given a higher priority than flight safety.”

The Lessons for Today’s Safety Engineers

This is but one of many disasters that underlines the importance of the role of the Safety Engineer and the qualities that they must possess, if they are to be effective. Engineers must be able to express critical information and opinion in a timely and persuasive manner.

On occasions, this may be under considerable pressure, with a project facing significant stress. This is why Vanguard, in its 25 years of consultancy service, has long recognised that Safety Engineers must have knowledge, tact and, at times, more than a little courage. Fortunately, the need for courage to deliver unwelcome information is not often required and conditions of overwhelming external pressure are rare. In our experience, however, it is likely to occur at least once in any major project.

Sadly for the crew of Space Shuttle Challenger, that time arrived, but the opportunity was missed and the risks were realised.

This article was written by Theo Chieng with major contributions from Brendan Fitzgerald .

Photo Credit: Challenger space shuttle being transported to the launch pad. By NASA – https://www.dvidshub.net/image/760483/space-craft-hc-s-challenger; original from http://www.nbcnews.com/slideshow/technologyandscience/the-challenger-tragedy-in-pictures-41180120,