In retrospect, the missteps that led to the loss of the space shuttle Columbia seem so obvious. In every one of the 113 shuttle flights since the program began in 1981, small pieces of insulation foam peeled off the vehicle's external tank during launch and dinged the orbiter. In at least eight flights, larger hunks of foam detached from the bipod ramps (the insulation covering the areas where struts attach the external tank to the orbiter). During the launch of the shuttle Atlantis last October, a foot-long chunk fell from a bipod ramp and hit one of the solid-fuel boosters. But in the Flight Readiness Review for the next shuttle mission, NASA managers concluded that the foam strikes did not pose a threat. Instead of thoroughly analyzing the problem, they put out a perfunctory rationale including statements such as "Ramp foam application involves craftsmanship" and "All ramp closeout work was performed by experienced practitioners."
One minute and 21 seconds into Columbia's final launch on January 16, a briefcase-size piece of foam separated from the bipod area and slammed into the orbiter's left wing at more than 500 miles an hour. According to the Columbia Accident Investigation Board, which is due to release its report this summer, the impact most likely opened a breach in the wing's leading edge. On February 1, when the the shuttle reentered the atmosphere, superheated gases jetted through the hole like a blowtorch.