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The 248 page report on the Columbia disaster (available at http://www.caib.us/) is worrying – very worrying. This is not so much because of what is in the report, but because of what has been left out. The report gives a lucid account of what went wrong. How 81.9 seconds into the flight, a large piece of foam detached itself from the bipod ramp of the large external tank on which the orbiter sat, and how this piece of foam slammed into and damaged the leading edge of the orbiter’s left wing. Finally how this damage allowed super heated gasses to enter the wing during Columbia’s re-entry into the Earth’s atmosphere. This resulted in the loss of aerodynamic control, and ultimately the destruction of the Columbia and the loss of its entire crew. The report does not stop with the technical causes but repeatedly criticizes the culture of NASA which gave cutting costs and meeting artificially set deadlines a higher priority than the safety of the astronauts. Ironically the main purpose of the insulating foam was to keep the extremely cold propellants within the external tank from causing condensation and freezing of moisture on the outer skin of the tank which could lead to the formation of ice. This ice could break off and cause damage to the orbiter.
What is missing from the report is an answer to the simple question, “Who is responsible?” It discusses a “culture” without mentioning the individuals who created and worked within that culture. It calls for a change in the NASA culture without specifying how this is to take place.
The unlikely probability of a real change in NASA was demonstrated during NASA Administrator Sean O’Keefe’s recent press conference. When Shelby Spires of the “Huntsville Times” asked whether fixing the foam problem would require a costly redesign of the external tank, O’Keefe replied:
“We'll see. I mean, there may be an option down the road in which will be selecting to do something along those lines. Don't know. But the approach that I think very clearly articulated yesterday by the Accident Investigation Board membership was that … the issue of foam loss per se is not something they find as being totally disqualifying.”
The Accident Investigation Board was considerably less equivocating and recommended to “Initiate an aggressive program to eliminate all External Tank Thermal Protection System debris-shedding at the source with particular emphasis on the region where the bipod struts attach to the External Tank” (p. 225, Columbia Accident Investigation Board, Volume 1). Mr. O’Keefe then went on to explain that NASA’s solution would likely consist of heating the bipod and possible some other areas to eliminate the need in these spots for insulating foam. In short, instead of solving the problem of foam breaking off from the external tank, NASA is offering a band-aid. The shedding of foam has been a problem from the beginning of the shuttle program and foam has hit many parts of the orbiter over the years. If in general, the shedding does not cause serious damage, why worry? The late Richard Feynman addressed this question while investigating the Challenger disaster. He wrote, “The O-rings [whose erosion was responsible for the Challenger disaster] of the solid rocket booster were not designed to erode. Erosion was a clue that something was wrong. Erosion was not something from which safety could be inferred.” The foam of the external tank is not designed to shed. Instead of trying to calculate the probability of shedding foam doing substantial damage, the problem should be solved. One technically feasible but costly solution is to put a metal envelope around the external shuttle as existed on the Saturn V rocket.
The shuttle program does not need a band aid; it needs a solution. Before another shuttle is launched, it needs a real solution to the problem of shedding foam as required by the Columbia Accident Investigating Board. And even more importantly, before we ask men and women to risk their lives in space, we must be assured that the upper management of NASA puts their safety before budget cutting and meeting impossible deadlines.
Ed Ehrlich - 15 September 2003