HOUSTON – NASA relied on a flawed analysis of debris damage on Columbia and allowed a web of miscommunication to block a team of engineers from getting photos of the shuttle in orbit, accident investigators said Tuesday.
In some of the sharpest criticism voiced since the investigation board began digging into the cause of the disaster, chairman Harold Gehman Jr. called the computer model used to assess the damage done to the shuttle "rudimentary" and not meant to predict safety.
And former astronaut Sally Ride, the newest board member, said a failed request for military photos "looks as though it was literally a miscommunication."
The analysis led by NASA contractor Boeing Co. during Columbia's mission reviewed whether significant damage was done to the left wing by a chunk of hardened foam that came off the fuel tank during liftoff. Its conclusion that little harm was done was a crucial element in the belief by NASA that the seven astronauts would return safely.
But the analytical model had never been used before during an actual shuttle flight, Ride said.
Gehman, a retired Navy admiral, described the model as a spreadsheet, not a computational design, and noted that it was based on testing of much smaller debris — not anything nearly as large as the 2-pound piece that hit Columbia 81 seconds after liftoff.
Gehman said that although hindsight has revealed the analysis to be wrong, it doesn't mean the decision-making based on it was wrong at the time.
The engineers relying on the analysis during the Columbia mission realized they needed more data, Ride said. They asked NASA officials to request pictures of the orbiting shuttle, but none were ever taken.
In the two months since the disaster, attention has focused on flyaway foam insulation as a major suspect in causing the breach in Columbia's left wing. Superheated gases entered the wing, causing the shuttle to break apart over Texas on its way to a Florida landing.
NASA's video of the launch debris striking the wing was not clear enough. The engineers needed to know more about the speed and location of where the falling foam hit on the wing and the size of the foam itself, in order to properly assess the potential damage.
"If you had given them good information to start with, they could have given you an answer," she told reporters, referring to the analytical program used by engineers to assess damage. "But there wasn't enough information. So you're asking them to predict where something's going to hit but you can't tell them how it started."
All the unknowns "led this whole group to say, 'Get us more data, get us some photos."'
Speaking after Tuesday's hearing into the cause of the accident, Ride said the request for photos came out of a meeting that occurred Jan. 21 — just five days after Columbia was struck by foam.
Describing the miscommunication, Ride said it appeared that "one group was saying, 'Let's wait until the analysis is complete to see whether we need photos' and then that was interpreted as, 'There will be no photos.' In other cases, it was for different reasons. It's a pretty complex story. It's a real web of interpersonal communications."
Ride said this web apparently stretched even up to the astronauts aboard Columbia, who accepted the engineers' conclusion that they would be in no danger during their descent through the atmosphere on Feb. 1.
That conclusion by Boeing engineers, after just a week or so of analysis, was accepted by virtually everyone.
But other company engineers testified earlier Tuesday that the space shuttles' outer thermal protection layers were never meant to be struck by anything stronger than perhaps bugs or rain — certainly not a 2-foot-long piece of hardened foam.
Testimony by engineers and comments by board members seemed to reveal a culture in which problems became acceptable over time because no lives were lost.
NASA became accustomed to the more than 140 debris strikes that occurred on every flight. Such damage was viewed as a nuisance that called for more maintenance, these engineers told the board.
Recalling her own tenure as an astronaut unaware of the many life-threatening problems affecting a space shuttle, Ride said, "I'm not sure that it's an appropriate analogy, but I'd never heard about O-rings before the Challenger accident."
A member of the presidential commission that looked into the Challenger disaster, she added that NASA's same acceptance of routine hazards was evident then as well: "You survived it the first time, so suddenly it becomes more normal."
Gehman said he plans to release in the next few days a set of interim recommendations to NASA. These will include adopting measures for gauging spacecraft age and photographing shuttles in orbit every time they fly.
NASA has already asked the military to regularly take satellite images of orbiting shuttles, and the military has agreed to do so.