trictly technical terms, it was a chunk of foam about the size of a briefcase that downed the Columbia space shuttle in February.
But a scathing U.S. government inquiry has concluded that the root cause of the fatal crash was the culture at NASA, which for two decades had sacrificed safety in the pursuit of budget efficiency and tight schedules.
"NASA's organizational culture had as much to do with this accident as foam did," the Columbia Accident Investigation Board noted in a 248-page report released yesterday in Washington.
The report tied the Columbia crash to the U.S. National Aeronautics and Space Administration's repeated failure to give safety overriding priority.
"NASA had conflicting goals of cost, schedule and safety," Major-General John Barry, a member of the 13-member investigation board, told reporters. "Unfortunately, safety lost out."
The report, which took seven months and $20-million (U.S.) to compile, also chastises NASA management for failing to apply the lessons of the 1986 Challenger disaster. Both crashes killed the shuttles' seven-member crews.
"It didn't get fixed last time," lamented Steven Wallace, director of the Federal Aviation Administration's accident investigation office and another board member. "There has to be a different approach."
The U.S. fleet of space shuttles has been grounded since the crash. The board issued 29 recommendations to get the U.S. fleet of orbiters flying again.
But it ominously warned that if the past is any guide, NASA will fight making the changes, increasing the risk of future accidents.
"Based on NASA's history of ignoring external recommendations, or making improvements that atrophy with time, the board has no confidence that the space shuttle can be operated safely for more than a few years based solely on renewed postaccident vigilance," the report reads.
Among its recommendations, the board urges that more money be put into the shuttle program and that the agency's "self-deceptive" and "overconfident" culture be changed.
Less than two minutes into Columbia's launch Jan. 16, a piece of foam insulation estimated to have weighed less than a kilogram broke off from the giant orange fuel tank strapped to the shuttle's underbelly and struck the orbiter's wing. NASA engineers raised questions about the incident, requesting detailed satellite photos of any possible damage, but the pictures were never taken.
"From the beginning, the board witnessed a consistent lack of concern about the debris strike on Columbia," the report reads. "NASA managers told the board 'There was no safety-of-flight issue,' and 'We couldn't have done anything about it anyway.' "
When Columbia re-entered the Earth's atmosphere on Feb. 1, superheated air penetrated the wing and melted the shuttle from the inside where the foam had punched a manhole-sized breach. It took just 24 seconds for the craft to break apart at an altitude of 43,000 metres and scatter debris over parts of Texas and Louisiana.
Columbia's crew died from blunt trauma and a loss of oxygen within seconds after mission control lost signals from the shuttle, the investigation found.
In a statement, NASA administrator Sean O'Keefe said the agency had already begun to implement some of the recommendations the board issued earlier "and we intend to comply with the full range of recommendations released today."
He noted that NASA has already formed a group to "change the culture" of the agency.
Mr. O'Keefe acknowledged yesterday that NASA officials had "just plain missed" the gravity of foam debris, a problem witnessed on dozens of earlier shuttle flights.
Yesterday, U.S. President George W. Bush urged a thorough review of the entire report before any decisions are made about NASA's future. But he vowed that Columbia's demise wouldn't threaten the U.S. space program.
Relatives of the dead astronauts praised the sweeping report.
"I think it's very thorough, extremely thorough," said Jonathan Clark, husband of astronaut Laurel Clark. "From my perspective, it certainly hits right on the money."
NASA isn't the only villain in the report. The board also blamed the White House and Congress for failing to ensure that NASA's budget keep pace with inflation over the past decade. To cope with the crunch, the agency slashed its work force and relied increasingly on outside contractors.
U.S. commitments to build the international space station also diverted millions of dollars out of the shuttle's budget.
NASA aims to restart the shuttle program by the spring with the launch of Atlantis and plans to present a return-to-flight plan to Congress next week.