The shaming of Nasa: how safety was sacrificed and seven astronauts died

Nasa stood accused of complacency and suffering from safety "blind spots" yesterday in a damning final report into the Columbia shuttle disaster seven months ago.

Independent investigators attacked the organisation's flawed safety procedures, finding that those were as much to blame for the calamity, in which seven astronauts died, as technical faults. Without reform, "the scene is set for another accident", the report warned.

They highlighted Nasa's failure to heed warnings that insulation foam had broken away, damaging one of the shuttle's wings soon after take-off. Sixteen days later, on 1 February, the craft broke up on re-entry over Texas.

The 248-page report, the product of a $20m (£12.7m) investigation, castigates Nasa for failing to learn the lessons of the Challenger disaster 16 years ago, in which seven astronauts also died.

The report described a "self-protective" culture at the heart of an organisation that sends people on the most perilous journeys. That meant Nasa managers accepted increasing risks to the point where they saw some flaws as normal in the shuttle system. And safety concerns expressed along the chain of command in Nasa failed to reach top managers.

"Nasa had conflicting goals of cost, schedule and safety,'' Maj-Gen John Barry told reporters. "Unfortunately, safety lost out." The report said the agency discouraged dissenting views on safety issues, which created "blind spots". It said: "Nasa's organisational culture and structure had as much to do with this accident as the external tank foam."

The investigators condemned senior officials for overlooking technical problems brought to their attention. "From the beginning, the board witnessed a consistent lack of concern about the debris strike on Columbia," they said. Nasa managers told the investigation that "there was no safety-of-flight issue" and "we couldn't have done anything about it anyway". But the investigators found that they also failed to heed specific and repeated warnings about the possibility of calamity after foam from Columbia's fuel tanks struck a wing after its lift-off.

The mechanical cause of the disaster was identified long ago: a piece of foam on an external tank, the size of a suitcase, broke off 81 seconds after lift-off and punched a hole in the heat-shielding edge of the left wing. Upon re-entry, the gash allowed searing gases to invade the craft's structure and start to melt it.

Chunks of foam had hit the aircraft at least eight times in the past but with no adverse effects. The board accused the agency of "ineffective leadership" that "failed to fulfil the implicit contract to do whatever is possible to ensure the safety of the crew".

The board stopped short of suggesting action could have been taken to rescue the crew from the damaged shuttle. "Given the current design of the orbiter, there was no possibility for the crew to survive," it said. Nasa says a rescue operation would have been impossible. The most specific charge made was that engineers repeatedly raised questions over the possible implications of the debris strike. On three occasions during the 16-day mission, they asked for satellite photographs of the craft to allow them to check for possible damage to its skin. Those pictures were never made available.

A final video inside the crew compartment shows that three crew members had failed fully to don their prescribed pressure suits, helmets and gloves for re-entry. Three were without gloves. One had no helmet.

The board offered 29 recommendations for reform, including a shake-up of Nasa's managerial structure and the formation of separate safety divisions able to get the attention of top managers.

Nasa's head, Sean O'Keefe, said: "We have accepted the findings and will comply with the recommendations to the best of our ability." President George Bush said: "Our journey into space will go on."

The report placed some blame on the politicians. The White House, Congress and the Nasa leadership had put pressure on Nasa to maintain its schedule to keep up with the construction plans for the International Space Station and to cut costs, it said. Its budget lost 13 per cent of its purchasing power from 1993 to 2002.