Flatly contradicting his engineers, NASA head Sean O'Keefe said yesterday that he does not accept their premise that nothing could have been done to repair the heat tiles and save the crew of the space shuttle Columbia before it dived into its fiery re-entry from orbit.
Mr. O'Keefe's comments came as the National Aeronautics and Space Administration released a video showing the last images of the crew, shot as their ship slashed through the upper atmosphere's super-heated gas, which pulsed like red flashes outside Columbia's windows.
At times, they mug to the camera -- in one part, four of the seven astronauts can be seen joking and expressing awe at the incandescent glow outside.
"You definitely don't want to be outside now," mission commander Colonel Rick Husband is heard saying.
"What, like we did before?" astronaut Laurel Clark replies, to laughters from the others.
The videotape was discovered among debris on the ground, in Texas, five days after the Feb. 1 disaster. The 13-minute tape holds no investigative value. Because of heat damage, it ends in a pixilated blur, four minutes before the first sign of trouble and 11 minutes before mission control lost contact with the crew.
The astronauts had not been told that ground controllers were exchanging e-mails arguing over whether possible damage to Columbia's heat tiles could lead to a catastrophic failure.
NASA engineers have maintained that the only option left for Columbia was to chance a return to Earth. It was a scientific flight; the shuttle was not carrying the robot arm or tools that could have helped space walkers repair the damage. The cargo bay was packed instead with the SpaceHab lab module and 3.7 tonnes of research equipment.
The flight did not have a docking apparatus or enough fuel to enable Columbia to carry its crew to the space station.
Yet Mr. O'Keefe told reporters yesterday that "to suggest that we would have done nothing is fallacious. If there had been a clear indication [of problems], there would have been no end to the efforts."
The engineers' e-mail exchanges focused only on whether the crew could bail out or crash land should the heat-tile damage disable Columbia's landing gears.
While no formal contingency plan covers the case of a shuttle losing its thermal protection, Mr. O'Keefe mentioned NASA's resourceful handling of the Apollo 13 mission, when ground control found a way to rescue three moon-bound astronauts after their capsule was endangered by an exploding oxygen tank.