Canadian Consulting Engineer

Comment: Columbia Space Shuttle disaster shows the vulnerability of all engineered systems

There's a view in safety engineering that accidents are always avoidable. But is that the case in space exploratio...

February 11, 2003   Canadian Consulting Engineer

There’s a view in safety engineering that accidents are always avoidable. But is that the case in space exploration, too?

On February 1, 2003 the space shuttle Columbia broke up over Texas only 16 minutes away from its landing point at the Kennedy Space Center in Florida. Seven astronauts lost their lives. It’s the second space shuttle flight to end in failure in 113 missions. For some, the incident reminds them of the Challenger accident of 1986. For others, it reminds them of the vulnerability of engineered systems despite the best efforts of some of the sharpest minds on the planet.

Early theories of what caused the accident centred on a piece of falling insulation from the external fuel tank. It was thought that the insulation damaged some of the heat protective tiles. But Space Shuttle program manager Ron Dittemore said the engineering evaluation teams are now concentrating their efforts on ‘something other’ than the insulating foam. The real problem, he says, is to determine why there was extreme drag over one of the wings. As the analysis into the accident continues, it’s reasonable to believe that a definitive answer from NASA about the accident will not come for many more days.

Nine years ago, Paul Fischbeck, an engineering professor at Carnegie Mellon University conducted a risk analysis which showed the underside of both wings close to the fuselage to be particularly vulnerable to damage from debris. NASA used this information and brought changes to material selection and flight rules. In an interview after the Columbia tragedy Fischbeck said: “There’s risk associated with any engineered system, whether it be your school bus or a double-hull tanker or whether it be the space shuttle. There’s always a combination of events that can lead to an accident. You cannot make things risk-free.”

He raises a critical question about the role of safety in engineering design. Are engineers expected to understand all the possible modes of failure in a system? Should we expect as much success in the design of a house as we do in the design of a space shuttle? Is an accident always evidence that engineers did not design adequately? Fischbeck added that the real question to ask of the engineers at NASA is, “Did they do all they should have done?? At this point, it’s impossible to say.

Everything that mankind makes is eventually subject to failure. Our only defence against disaster is to understand the forces at work in any engineering application and take engineered systems out of service before they fail. To be able to guarantee safety is to be able to guarantee sufficient knowledge of all the factors involved in a system’s operation. This is not to suggest that engineering is guess work. It isn’t. It’s just that there are some applications, like space, where our knowledge is not at the same level of comfort as other areas. Perhaps this is why some refer to it as the final frontier.

The shuttle crew consisted of commander Rick Husband; pilot William McCool; payload commander Michael Anderson; mission specialists David Brown, Laurel Clark and Kalpana Chawla; and Israel’s first astronaut, Ilan Ramon. It’s uncertain how much warning the astronauts had of their impending danger, but at some point it would have been clear to them. There would have been a moment, perhaps only an instant, when the astronauts would have realized that they were not going to make it back.

On January 16, 2003 Columbia took off from Kennedy Space Center. Its mission was to conduct some 80 research experiments. It started the way every other expedition has ever started: with hope, courage and anticipation.

And yet, a week after the accident the picture looks much different. Regardless of whether or not space accidents are truly avoidable there are numerous engineers who (rightly or wrongly) carry the burden of disaster on their minds and in their hearts. There are families who are without their loved ones because (it seems that) our profession may have failed them. And there are additional astronauts now in training who at some point in the future will rely on engineers to guide them safely into space… And bring them safely home.

Paul H. Boge is an engineer with Boge & Boge in Winnipeg.

Sources
NASA
U.S. Department of State
CNN.com
Canadian Press
Arizona Republic


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