Feb. 1 marks the 10th anniversary of one of the most tragic events in human spaceflight: the loss of Space Shuttle Columbia and its crew. The shuttle was destroyed upon re-entry by a flux of super-heated air, estimated to be about 2,760 degrees Celsius, coming through a breach in the reinforced carbon-carbon left wing’s leading edge. The heat, reaching behind the thermal protection system, resulted in thermal degradation of structural properties of the left wing, causing destruction of the insulation that protected the leading edge support structure and melting the aluminum wing spar. Destruction of the crew module took place over a period of 24 seconds, beginning at an altitude of 42,672 meters and ending at 32,000 meters, leaving the crew with no chance of survival.
The Columbia Accident Investigation Board was convened by NASA to investigate the event. The board determined that the leading cause of the accident was the impact of the shuttle’s left wing with a piece of foam coming off the external tank’s bipod fitting 81.7 seconds after launch. The impact caused the breach in the wing’s leading edge, creating the conditions for the re-entry breakup.
As in all previous fatalities in human spaceflight — both in U.S. and Soviet space programs — the Columbia disaster was not an accident at all. What caused the release of a piece of foam during ascent was not an “unforeseen and unplanned event or circumstance,” as the definition of “accident” would imply; the external tank was defective by design, and the phenomenon of debris shedding was well known. According to the investigation board, damage caused by debris occurred on every space shuttle flight, and STS-107 was the seventh time that a release of foam from the bipod ramp was recorded.
The organizational failures that led NASA to downplay or dismiss all accident precursors as “acceptable risks” are well documented in the board’s report. The event that doomed Columbia was noticed during the second day of the ill-fated mission, upon reviewing launch camera photography. Mission Control Center even told the crew that there was “absolutely no concern for entry” because the phenomenon had been seen before.
“Things are happening and they often start as very small things,” Mike Ciannilli, NASA test director, said in an interview. “Even the last few years, we didn’t really understand carbon-carbon, its strengths and its weaknesses.” The general feeling was that a chunk of low-density foam insulation could not cause much damage. In fact, the impact of the acceleration component to the relative velocity of the two bodies was completely underestimated: The foam shredded the reinforced carbon-carbon panel like it was made of paper when Columbia rammed into it at Mach 2.46 (over 3,000 kilometers per hour).
Bryan O’Connor, who at the time was NASA chief of safety and mission assurance, stated that a major cause of the Columbia disaster was complacency. “When, after the accident, we donned the corrective lenses of the mishap analyst, it became clear that we had been fooling ourselves in some catastrophic ways,” he said. “The hardware had been talking to us, and what we had believed at the time to be rational risk management looked in retrospect more like rationalization of inconvenient warnings.”
According to O’Connor, while the orbiters were performing better and better on each flight, people at NASA were forgetting the very nature of the shuttle program, a “30-plus year flight test program during which NASA performed a variety of operational mission objectives.”
The shuttle was retired in 2011 after supporting the assembly of the international space station. Why is it still important to remember and study the Columbia accident?
With Columbia we lost much more than the crew and an orbiter with all its mission hardware; we lost an entire space program and a large part of its engineering knowledge. The space shuttle was a highly complex and innovative vehicle, designed to ferry back-and-forth a crew of up to eight people and to carry large military payloads to low Earth orbit. A set of wrong assumptions about its reliability and the need to satisfy a wide array of mission profiles, including the never utilized ability to fly into polar orbit from Vandenberg Air Force Base, Calif., led to an unsafe and vulnerable design.
We are witnessing the beginning of a new and promising era in human spaceflight, the commercial era.
The focus of commercial space is very much on cost-cutting, while vague assurances are made about safer vehicles. Sometimes safety is even presented as a stubborn obstacle to industry development and progress. The commercial human spaceflight industry needs to remember that the primary goal of the shuttle program was cutting the cost of transportation to orbit by an order of magnitude, a goal that failed miserably. As was the case with the supersonic Concorde, the shuttle was doomed by being both expensive and unsafe. Being expensive made it in turn unaffordable to undertake any further development or safety modification. But even being expensive to operate did not stop either the shuttle or Concorde from operating for about 30 years. What ultimately ended these programs was their inadequate safety.
We hope that the emerging commercial operators will keep alive the lessons learned from Columbia, making sure not to fall into the same mistake.
Andrea Gini is editor-in-chief of Space Safety Magazine, which, along with its sponsors, the International Association for Advancement of Space Safety and International Space Safety Foundation, has released, as part of the latest issue, a 16-page special report titled “Remembering Columbia,” to commemorate the event, remember the victims and ensure that the lessons learned on that fatal day will be preserved and applied to the next-generation space programs. You can download the issue at SpaceSafetyMagazine.com.