The fatal break-up of the Columbia space shuttle was caused by long-standing flaws in Nasa's staff culture as much as technical problems, an independent investigation has found.
Nasa failed to do all that was possible to safeguard the crew
In its final report, published on Tuesday, the Columbia Accident Investigation Board (CAIB) said that while mechanically the orbiter was lost because of a breach in the heat shield, management blunders and organisational errors at the space agency were as much to blame.
It said that while the current space shuttle was not inherently unsafe, a number of mechanical changes should be made in order to ensure safety in the short term.
"The board strongly believes that if these persistent,
systemic flaws are not resolved, the scene is set for
another accident," the report said.
Columbia disintegrated as it re-entered the Earth's atmosphere on 1 February, killing its crew of seven astronauts.
The report could have far-reaching implications for the future of Nasa's human space flight programme.
Nasa administrator Sean O'Keefe said his agency would follow the report's recommendations.
"We have accepted the findings and will comply with the recommendations to the best of our ability," he said in a statement.
"The board has provided Nasa with an important road map, as we determine when we will be 'Fit to Fly' again."
The final conclusions reaffirmed the view that a breach of the heat shield caused the break-up.
In July, following extensive simulation tests, the Columbia Accident Investigation Board (CAIB) members said a piece of foam insulation hitting the shuttle's left wing had blown a hole in the panel.
When the shuttle prepared to land, super hot gases would have penetrated the hole, causing it to disintegrate.
But the report said that the growing culture within the space agency, whereby "little by little, Nasa was accepting more and more risk in order to stay on schedule," meant that the problem was overlooked.
The report said that mission managers had fallen into the habit of accepting defects in the shuttle system as normal and ignoring them.
During Columbia's ill-fated mission Nasa managers missed at least eight opportunities to evaluate possible damage to the orbiter's heat shield, since similar foam strikes had occurred in the past with no adverse effects.
Certain Nasa staff did make requests for images to be taken of Columbia in orbit to assess the damage, but these were never acted on.
Nasa has since admitted that if the problem had been known by the seventh day of the mission, the shuttle Atlantis could have been rushed into space in enough time to evacuate Columbia.
Nasa has had to face the losses of two other crews since the start of the space age, with the Apollo 1 launch pad fire in 1967 and the Challenger disaster in 1986.
The report says that despite the loss of the Challenger, in which seven astronauts also died, the space agency has improved little in its attitude towards safety.
Speaking at a news conference after the report was published, one board member, Major General John Barry, said:
"Nasa had conflicting goals of cost, schedule and safety" and that as the agency began to operate "too close to too many margins, unfortunately safety lost out".
This occurred against a background of massive budget cuts, with Nasa losing 13% of its purchasing power from 1993 to 2002 and over 10,000 staff.
As a result, "safety and support upgrades were delayed or
deferred, and shuttle infrastructure was allowed to
The panel says the foam debris definitely caused the breach
Ultimately, the 248-page report says, the agency suffered from "ineffective leadership" that "failed to fulfil the implicit contract
to do whatever is possible to ensure the safety of the
According to the report Columbia's seven crew died within second of the signals from the orbiter being lost - the actual cause of death being attributed to blunt trauma and loss of oxygen.
"The destruction of the crew module took place over a
period of 24 seconds beginning at an altitude of
approximately 140,000 feet," the report said.