1 February 2003 was one of the darkest hours in the annals of human exploration of space. That was the day the space shuttle Columbia disintegrated in the earth's atmosphere over Texas and snuffed out the lives of seven astronauts, one of them India-born Kalpana Chawla. Now, a new 400-page report examines the tragedy in detail and relives the last moments in the astronauts' lives.
While many details of the Columbia's last flight have long been known, this was the most extensive study ever performed on how the astronauts died and what could be done to improve the chances of survival in a future accident.
The report reconstructs the crew's last minutes, including the warning signs that things were going badly wrong and alerts about tyre pressure, landing gear problems and efforts by the computerised flight system to compensate for the growing damage. It listed five ''lethal events'' related to the breakup of the shuttle, including depressurisation of the crew module, the forces of being spun, the exposure to vacuum and low temperatures of the upper atmosphere and impact with the ground.
It bluntly concludes that better equipment in the crew cabin would not have saved the astronauts and the only way to save lives in such an eventuality is to prevent its occurrence in the first place. ''The breakup of the crew module and the crew's subsequent exposure to hypersonic entry conditions was not survivable by any currently existing capability…. there is no known complete protection from the breakup event except to prevent its occurrence.''
Although the shuttle broke up during re-entry, its fate had been all but sealed during ascent, when a small piece of insulating foam broke away from an external fuel tank and struck the leading edge of the craft's left wing. The foam punched a hole that would later allow superheated gases to cut through the wing's interior like a blowtorch.
During descent, the crew cabin broke away from the ship and started spinning rapidly. Analysis of the wreckage indicated the crew members had flipped cockpit switches in response to alarms that were sounding. The astronauts had also reset the shuttle's autopilot system, the report said.
But rapid depressurisation caused the Columbia crew to lose consciousness, and medical findings show that they could not have recovered, said the report, which took four years to compile.
Analysis shows the astronauts' shoulder harnesses failed and their helmets did not adequately protect their heads. The lack of safety restraints caused traumatic injuries. The investigation also found problems with the shuttle's seats and parachute landing system, which requires astronauts be conscious to operate manually.
Even if the safety gear had worked, the astronauts would have died due to the winds, shock waves and other extreme conditions in the upper atmosphere.
Much of what is in the report was discovered by the Columbia accident investigation team, which released a series of findings and recommendations six months after the disaster.
The panel advised retiring the space shuttles as soon as NASA finishes using them to complete construction of the International Space Station, a $100-billion project of 16 partner countries that has been under way for more than a decade. The shuttle Challenger broke apart in 1986.
Since the accident, NASA has flown 11 shuttle missions and has nine left in its schedule. A 10th mission to fly a physics experiment to the space station is under consideration.
Designing spacesuits that are more automated and integrated into future spaceships is among 30 recommendations made in the report.
In a conference call with reporters on Tuesday, N Wayne Hale, Jr., a former head of the shuttle program, said, ''I call on spacecraft designers from all the other nations of the world, as well as the commercial and personal spacecraft designers here at home, to read this report and apply these lessons which have been paid for so dearly.''