The 250 page Columbia Accident Investigation Board (CAIB) report into how the shuttle disintegrated as it re-entered the Earth's atmosphere on February 1, killing all seven astronauts, is to be released in Washington.

The CAIB has compiled 35,000 documents and took evidence from hundreds of NASA officials and ex-officials and experts.

Investigators are certain, however, that a foam panel that came off during takeoff on January 16 is the "smoking gun".

They believe the panel pierced the heat-insulating skin around the shuttle, letting in boiling gases that caused the shuttle to break apart on re-entry.

The CAIB has produced a speedy report in a bid to help the National Aeronautics and Space Administration (NASA) resume manned flights as soon as possible -- NASA hopes by early next year.

But the inquiry, led by Harold Gehman, a retired admiral, will also recommend changes to the space agency's organisation in a bid to avoid the errors of judgement that it believes contributed to the disaster.

Investigators went through e-mail messages sent by ground engineers during the mission that described the potentially fatal impact of the damage caused by the loosened foam tile.

But NASA chiefs have said they did not see the messages nor receive any warning. And they rejected a Defense Department offer to use its spy satellites to take pictures of the shuttle after it was informed of an incident during the takeoff.

Though no details of the reforms have been given, Gehman, a disaster troubleshooter who also led the inquiry into the attack on the USS Cole in Yemen in 2000, outlined his concerns when he spoke to the Senate Commerce Committee in March.

"We find the safety organisation on paper is perfect, but when you bore down a little deeper, you don't find any 'there' there," he said.

Gehman has also made technical recommendations to prevent a repeat of the disaster, including a systematic inspection of the carbon fibre panels that protect the front of the shuttle wings which were damaged by the panel.

The CAIB also said that astronauts should be able to carry out space inspections of the protective skin and carry out repairs. At the moment, that is not possible.

NASA has already guaranteed that all recommendations will be carried out.

The agency has set up a committee to check all measures before the resumption of shuttle flights.

But the CAIB could also demand the setting up of an independent structure to monitor NASA's work and progress in safety areas, which would almost certainly be welcomed by Congress.

The report could also play a key role in determining NASA's future budget.

President George W. Bush insisted last week, however, that a space programme was crucial for any country seeking to stay in the forefront of cutting edge technology.

And despite the shock of a second shuttle disaster after the 1986 Challenger explosion, the American public seem willing to accept the risks of space missions.

A CNN/USA Today/Gallup poll released last week said 43 percent of those asked deemed that one accident per 100 flights was acceptable, and 32 percent said one accident in 50 flights was acceptable.

For University of Pennsylvania bioethicist Paul Root Wolpe - NASA's first official bioethicist - space exploration is worth the risk.

"We have gotten overly sensitive - people risk loss of life for things that have much less societal value," Wolpe said.

"Human beings, in my view, are exploring creatures," he added, and when it comes to astronauts: "they are not naive about the risks."

NASA has lost two shuttles in 113 missions.

SPACE.WIRE