Fatal impact

Tragically, the cause of this disaster had been spotted during the launch, but a series of mistakes led managers and engineers to underestimate the danger to the Shuttle. Stress and vibration during Columbia's launch 16 days earlier had shaken loose a large chunk of lightweight insulating foam 1 from the bipod struts that supported the Shuttle's nose above the external tank. As the foam flew off, ground-based video cameras saw it strike Columbia's wing.

NASA immediately began to assess the risk, but managers felt that comparisons with similar

ILL-STARRED MISSION

Columbia soars skyward on 16 January 2003, its underside already damaged by the fatal impact that would doom its return to Earth 16 days later.

impacts in the past (often noticed only when the orbiter returned to Earth with scars) suggested there was little to worry about. But several key factors had been missed - the lost chunk of foam was much larger than on any previous mission, and struck the Shuttle at a different angle and at much higher speed. And although no one could have known it, the debris had hit a very vulnerable spot - the leading edge of the wing, which received most of the heat during re-entry. As Columbia re-entered the atmosphere at 24 times the speed of sound, the usual sheath of hot gases developed around it, but found their way inside the Shuttle through the hole in the wing. At an altitude of 70km (44 miles), the orbiter's wing broke up, taking the rest of Columbia with it.

ALL LOST

(Left) The crew shortly before setting off on the STS-107 mission. Tragically they all perished when Columbia broke up in the skies over Texas (right).

"Their mission was almost complete, and we lost them so close to home

President George W. Bush, 4 February 2003

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