Since the Columbia disaster and the full-scale investigation that followed, the shuttle program "went into higher gear," NASA chief Sean O'Keefe said last week. "It prompted us to resolve questions that had been lingering for the last 10 years."

President George W. Bush's new space program announced in mid-January, including another manned moon mission and possibly a manned mission to Mars, settled for NASA "the issue of whether or not there is a direction of a focus," said O'Keefe.

The exhaustive investigation and report on the causes of the accident by the Columbia Accident Investigation Board (CAIB) "had a significant impact on the pace the decisions were made."

Early on Saturday, February 1 2003, the families of the seven Columbia astronauts were gathered in a building alongside the runway on which the shuttle was to land at the Kennedy Space Center on the Florida coast.

Nearing 9:00 am (1300 GMT), the moment when observers were expecting to hear the sonic booms that normally signal a shuttle re-entry, an incandescent hail of flaming pieces of metal was showering down on a broad swath of Texas and Louisiana.

The shuttle, burned up by friction-heated air at 2,000 degrees F.as it plummeted Earthward through the upper atmosphere, had disintegrated into a mass of glowing space junk.

Along the path of destruction, amateur cameramen filmed the stunning spectacle of flaming stars set against the azure sky, not comprehending what they were seeing.

Two days later, the US Congress established the CAIB to probe the accident, determine its causes, examine NASA's operating methodology and fix blame.

Headed by retired Admiral Hal Gehman -- who investigated the attack on the USS Cole in Yemen in October 2000 -- the CAIB seven months later published a report that was damning for NASA, detailing its errors, and the erosion of safety procedures since the shuttle Challenger exploded on takeoff in 1986.

The Columbia disaster, it said, was caused by a clear technical fault, but also by a series of fatal flaws in NASA's own command and decision-making apparatus.

The technical flaw was a critical breach in the ceramic tiles that made up the shuttle's protective heat shield and should have protected it from the excruciating heat of re-entry.

It was caused during takeoff when a large chunk of insulating foam broke free from one of the shuttle's external fuel tanks and crashed into the leading edge of the left wing. The spent fuel tanks themselves were jettisoned 81.7 seconds after takeoff.

"During re-entry, this breach in the thermal protection system allowed superheated air to penetrate though the leading edge insulation and progressively melt the aluminum structure of the left wing," said the CAIB's report last August.

The result was "a weakening of the structure until increasing aerodynamic forces caused loss of control, failure of the wing, and breakup of the orbiter.

"There was no possibility for the crew to survive."

Pieces of insulation breaking loose from the external fuel tanks was not new; the phenomenon had been observed in earlier shuttle takeoffs and NASA engineers had classified it as a minor threat not warranting remedial action, the CAIB noted.

But the big shock in the CAIB report was the revelation that, during the 16 days Columbia orbited the earth - a timebomb waiting to explode on re-entry - NASA's highest officials paid no attention to a series of alarming warnings by its technicians calling for a visual inspection of the shuttle's exterior by the crew before re-entry.

That, the CAIB concluded, was the fault of "organizational causes ... rooted in the history and culture" of NASA's space shuttle program.

Those causes, it said, go back to "original compromises ... required to gain approval for the shuttle ... years of resource constraint, fluctuating priorities, schedule pressures (and) reliance on past success as a substitute for sound engineering practices."

There were, said the CAIB report, "organizational barriers that prevented effective communication of critical safety information and stifled professional differences of opinion (and) an informal chain of command and decision-making processes that operated outside the organization's rules."

The conclusions triggered anger in Congress, where lawmakers demanded a wholesale re-defining of the space agency's policies before any resumption of the shuttle program.

The long-term answer came from Bush when he announced the retirement of the shuttle program in 2010 and its replacement by a far more ambitious program to include resumed manned flights to the moon beginning in 2015, then possibly on to Mars.

Before then, beginning next Fall, NASA is scheduled to resume a full program of shuttle launches tasked with finishing construction of the orbiting International Space Station.

To accomplish that, the remaining shuttles - Atlantis, Discovery and Endeavor - will often be on standby simultaneously, with a total of five missions per year before they are consigned to a museum.

Before the loss of Columbia, NASA chief O'keefe had spoken openly of keeping the aging shuttle fleet, put in service in 1981, flying until 2020 for want of a replacement.

But the CAIB report, pointing to the age of the shuttle, cautioned that NASA should completely re-evaluate the fleet to ascertain its space-worthyness beyond 2010.

Bush ended debate over the costly and uncertain procedure when he concluded the time was at hand for the nation to have an entirely new spacecraft.

SPACE.WIRE