THE Columbia's crew likely knew for as long as 41 seconds that they did not have control of the orbiter before they were knocked unconscious. Nasa's reconstruction of their final moments:
On the Columbia's re-entry into the atmosphere 20km over Texas, hot atmospheric gases blast inside through a hole punched by a piece of insulating foam.
The gases melt the ship's structure. The crew cabin breaks away from the ship and starts spinning rapidly.
Astronauts try to regain control of the craft, by flipping cockpit switches as alarms sound and resetting the autopilot system.
Rapid depressurisation causes the crew to lose consciousness within seconds.
As the cabin begins its wild gyrations during descent, the crew members are protected only by their lap belts. Shoulder harnesses fail because the inertial locks, like those on car seat belts, are not designed for sideways motion. The astronauts' torsos are thrown around violently.
Helmets on the pressure suits do not conform to the crew members' heads and thus give them no protection from impacts.
The crew are exposed to a near vacuum.
The burning shuttle crashes to the ground.
REUTERS, LOS ANGELES TIMES