1. Understanding big accidents

2. NASA's failing grade

3. The blame game

4. Accidents: Normal?

5. Holey-headed reactor

Debris from the space shuttle Columbia streaks across the Texas sky Feb. 1. 2003. Amateur photographer Jason Hutchinson made the photo in north Dallas.
AP Photo/Jason Hutchinson

Tragedy in space
The Feb. 1, 2003 burn-up of space shuttle Columbia killed its crew of seven, and seared its way across the public imagination. On Aug. 26, the Columbia Accident Investigating Board (CAIB) released its final report, explaining what caused the accident, and detailing steps NASA must take before launching another shuttle.

The board placed immediate blame on a chunk of foam that broke off during takeoff and smashed essential heat protection on Columbia's left wing. But more broadly, the CAIB report blamed the NASA organization:

The foam debris hit was not the single cause of the Columbia accident, just as the failure of the joint seal that permitted O-ring erosion was not the single cause of Challenger [which exploded in 1986, killing all seven on board].

NASA's organizational culture and structure had as much to do with this accident as the external tank foam. The shuttle program's safety culture is straining to hold together the vestiges of a once-robust systems safety program.

Shuttle program safety personnel failed to adequately assess anomalies and frequently accepted critical risks without qualitative or quantitative support... .

In briefing after briefing, interview after interview, NASA remained in denial. In the agency's eyes, "there were no safety-of-flight issues," and no safety compromises in the long history of debris strikes on the thermal protection system.

NASA has developed what it calls a comprehensive response to the technical and organizational deficiencies listed by the board.

Miscommunication: It's a human thing
As The Why Files tries to understand accidents -- whether giant blackouts or shuttle crashes -- we hear over and over about organizational culture. For example, Vicki Bier, a professor of industrial engineering at University of Wisconsin-Madison who studies nuclear plant safety, agrees that culture -- an organization's system of expectations, rules and power relationships -- played a central role in NASA's two shuttle disasters. "Although the technological details were quite different than the Challenger disaster, the organizational issues seemed remarkably similar. So we had not learned the lessons of Challenger, or had learned them and forgotten."

Before Challenger's final flight in 1986, engineers cautioned that the giant O-rings sealing the booster segments had not been tested in temperatures as cold as on launch day, but they were overruled, perhaps because the seals had never completely failed. That sequence of events, Bier says, reflects the "normalization of deviance," a high-falutin' way of saying that warning signs gradually become acceptable when bad things don't happen. But the seals leaked, Challenger exploded, and seven died.

Similarly, before Columbia's burn-up, previous launch videos had shown foam detaching from the fuel tank and striking the shuttle, again without causing perceptible harm. "There were lots of instances that did not cause disaster," Bier says, "so there were some people at NASA saying, 'I can't imagine this would happen. Foam is light, it can't cause damage. We've known about this for years.'"

What you don't know can still hurt
Within a day of Columbia's launch, engineers studying a launch video noticed a large hunk of foam striking the wing. After a heated discussion, they asked superiors to order telescope photographs of the shuttle to assess the damage, but the requests died in NASA's hierarchy. (Granted, if the photos had shown major damage, rescue may have been impossible. But without photos, NASA couldn't even try to repeat the engineering heroics that rescued Apollo 13, after an explosion robbed the spaceship of oxygen, water and propulsion while en route the moon.)

Columbia investigator Scott Hubbard peers into a damaged wing panel after another test of the foam impact. If it had this kind of hole, Columbia was doomed. Photo: Columbia Accident Investigation Board

But when NASA managers were considering the photo request, nobody knew how a hunk of foam would damage the shuttle. "There were zero tests," says Stephen Johnson, an associate professor of space studies at the University of North Dakota. "I was amazed at the lack of actual analytical support about the conjectures they were making about ... what the damage would be on the wing from a piece of foam of a given size."

Curiously, just after Columbia's incineration, some NASA managers were publicly speculating about damage from insulating foam. So while NASA knew chunks of foam were striking essential insulating surfaces, it never bothered to run tests. When the tests were finally performed months after the accident, the result was serious wing damage.

After the Columbia crash, shouldn't some heads roll at NASA?

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