Columbia Space Shuttle Explosion

During launch, an external fuel tank is positioned between the two solid rocket boosters. Although the boosters are recovered and reused after liftoff, the external tank (which has been sprayed with foam insulation) is neither recovered nor reused. Instead, it is jettisoned into a remote area of the ocean where it breaks apart.

Before it was used on the actual launch of shuttle missions, insulation for the external tank was tested in-flight on an F-15B. After the insulation material was approved and actually applied to external fuel tanks, bits and pieces of the substance began to break loose during various shuttle launches. NASA managers considered that phenomenon to simply be a maintenance issue - until January of 2003.

Assessment of the impact which breakaway insulation could cause to the shuttle changed the day after Columbia launched on January 16. Officials examining photos and videos, which strategically placed NASA cameras took during the launch, noticed something potentially concerning. Eighty-two seconds after liftoff, a piece of external-tank insulation broke loose (see it happen at about seven minutes into the video) and appeared to strike Columbia's left wing.

If that debris were a chunk of ice, as at least one Langley Research Center engineer speculated, it would have weighed more than sixty pounds. And a sixty-pound object, in motion at those speeds, "would be the equivalent of a 500-pound safe hitting the wing at 365 mph."

Thoughts like that began to worry some NASA managers. What if the insulation problem were no longer just a maintenance issue?