Poor pressure suit design led the seven astronauts aboard the Columbia space shuttle to black out almost immediately when the craft broke apart during re-entry in 2003 and they probably were killed as their bodies were buffeted by the craft's violent contortions, a NASA panel said yesterday.
At least three other design flaws associated with seat belts, helmets and parachutes also could have caused their deaths if they had survived those problems, the panel said in its final report on the incident.
Although correcting the deficiencies would not have saved the astronauts, because the catastrophic accident - occurring at high altitude and hypersonic speed - was "unsurvivable," the report noted, such corrections could lead to improvements in survival in less serious accidents.
Even though parts of the final report were redacted to protect the sensitivities of the astronauts' families, it represents the most graphic and harrowing account of the seven fliers' final moments.
NASA officials already knew the crew members died either from a lack of oxygen or from impact with objects in the cabin, and the new report was unable to distinguish between the two possibilities. But it did further understanding of events by offering a catalog of all the things that are now known to have gone wrong and providing new details about the crash.
One comforting conclusion from the 400-page report is that, after the first seconds, the astronauts probably were unconscious and never knew what was happening.
"On behalf of their colleagues and families, I can say that we are relieved that we discovered this," astronaut Pam Melroy, deputy project manager for the investigative team, said at a news conference.
The accident was caused by a piece of foam insulation that broke off from the external fuel tank during launch on Jan. 16 and damaged the leading edge of Columbia's left wing. The wing was not inspected because the prevailing belief was that such foam could not cause significant damage.
On its re-entry into Earth's atmosphere Feb. 1, Columbia broke up over Texas, killing all seven aboard.
A 2003 report presented a scathing indictment of a "broken safety culture" at NASA that allowed the accident to occur.
The first problem that crew members encountered involved their pressure suits, which were not part of the shuttle's original equipment but were added after the 1986 Challenger disaster. Because of design problems with the suits, the crew cannot keep the visors of their helmets down throughout entry because that leads to high oxygen concentrations in the cabin. And wearing the suit's gloves makes it difficult or impossible to perform many required tasks.
At the time of the accident, three crew members were not wearing gloves, one did not have his helmet on, and none had the visor down. All of the crew members immediately lost consciousness from depressurization.
But "the crew was doing everything they had been trained to do and were doing everything right," Melroy said. NASA has since changed rules for donning the suits, she said.
As the craft began its wild gyrations during descent, the crew members were protected only by their lap belts. The upper-body belts did not hold them in place because the inertial locks, like those on car seat belts, were not designed for sideways motion. The astronauts' torsos were thrown around violently.