Members of the Columbia Accident Investigation board said Thursday that a problem with space shuttle hardware could have allowed a 40-pound bolt fragment to zip free and possibly smash into the spacecraft during some future launch.
The flawed device, called a bolt catcher, can now be fixed easily and will present no problem when the shuttle starts flying again, experts said.
But if the faulty equipment had not been found, it had "the potential to be catastrophic in the future," said Air Force Maj. Gen. John Barry, a member of the investigation board.
CBS News space consultant Bill Harwood says the bolts are used to attach the two white, cylindrical rocket boosters to the sides of the external fuel tank strapped to the shuttle's underbelly.
When the boosters have to separate and fall away after the fuel is expended, the bolts explode and split in two. The bolt catcher is supposed to capture the fragments, but the recent findings suggest it might not be as strong as is necessary.
The board's chairman, retired Adm. Hal Gehman, said the bolt catcher was supposed to withstand 68,000 inch-pounds of force when the severed bolt is slammed inside, but in tests the device came apart under just 56,000 inch-pounds of force.
There is no indication that a bolt piece contributed to the Columbia accident. Instead, investigators believe a piece of foam from the insulation of the external fuel tank broke off, striking and damaging some of the protective panels on the shuttle.
But the Columbia accident indicated how serious a problem with the explosive bolts could be. The foam suspected of causing the Columbia disaster weighed 1.7 pounds. One half-piece of bolt weighs 40 pounds.
A particle weighing that much smashing into the shuttle would have caused major damage to the craft's heat shield, officials said.
Now that the problem is known, board member Scott Hubbard said the device can be fixed so it will not pose a threat to future space shuttles.
But the bolt problem may never have come to light were it not for Columbia's tragic end and the investigation that followed.
At a news conference, Barry said investigators found radar evidence of an object drifting near Columbia just moments after solid-rocket boosters expended their fuel and separated from the shuttle's external fuel tank during the spacecraft's launch in January.
Barry said that during that phase of the flight, about 126 seconds after launch, engineers say there should be no debris near the orbiter.
Investigators looking for a possible source of the radar image determined that the object could have been part of the heavy, 2-foot-long bolt.
But while repairing the flaw might be straightforward, the discovery still raises questions about NASA's process for limiting risks to the shuttle.
Barry said the bolt catcher used on Columbia was made by a new manufacturer and records showed it had not been tested dynamically. When board investigators conducted a test on the device, it failed.
"How that gets into the system, that sort thing makes people scratch their heads. Who knows if there's anything else working out there that
doesn't meet the specs," Harwood said. "They're thinking about that and try to identify systems that could have similar problems."
In a public hearing Thursday, experts said the National Aeronautics and Space Administration had a lean budget for almost a decade and was forced to move money from the space shuttle program to pay for other space agency programs.
The board is investigating whether a shortage of funds in the shuttle program compromised safety.
"The shuttle has been, if you want, the cash cow to finance the rest of the parts of the agency," said John Logsdon, a board member and a professor at George Washington University.
Budget issues aside, space program supporters note that NASA has never said the shuttle was 100 percent safe.
"You're taking a 120-ton vehicle accelerating it to 5 miles per second. That's eight times faster than the bullet from an assault rifle," Harwood points out. "That will never be risk-free."