Two Years After Columbia, Some Blunt Language From RTF Task Force

Don't rely too much on computer models that haven't yet been tested. That warning came Monday from NASA's Return To Flight Task Force on the eve of the second anniversary of the Columbia shuttle tragedy.

It was two years ago on Tuesday that the space shuttle, just moments away from touchdown at the Kennedy Space Center, disintegrated over East Texas and West Louisiana. The cause was determined by a panel of experts to be a hole punched in the shuttle's left wing as it lifted off -- a hole caused by a chunk of errant foam from the space plane's external fuel tank. Throughout the shuttle's two-week mission, astronauts were unaware of the fatal damage.

ANN reported that the shuttle's controllers, in a conference call during the flight, discounted the damage caused by the falling foam -- not because they didn't consider it a threat -- but because they figured there was nothing they could do about it while the spacecraft was still in orbit.

"NASA has yet to demonstrate the rigor of the models necessary to certify the space shuttle TPS [thermal protection system] including the ET [external tank]," the report said, without specifically mentioning the tests. "Without validation of models, they should not be used for certification or risk assessment."

Indeed, the space agency's propensity to depend on computer modeling was never more clearly demonstrated than during the conversations that NASA says ultimately doomed Columbia.

"Really, I don't think there is much we can do," said shuttle manager Linda Ham said in a January 21st conference call. Columbia was still in orbit at the time. "It's not really a factor during the flight because there isn't much we can do about it."

NASA, using an inexperienced Boeing engineering team that had never made such a critical decision before, decided that the impact of foam which later proved fatal to the orbiter was no factor. The biggest reason: there were no computer models to predict the effects of such a strike. Those that were available were apparently misinterpreted.

It wasn't as if Ham disregarded advice on the issue of the foam strike. "We were all trying to do the right thing. All along, we were basing our decisions on the best information that we had at the time," she said. "Nobody wanted to do any harm to anyone. Obviously, nobody wants to hurt the crew. These people are our friends. They're our neighbors. We run with them, work out in the gym with them. My husband is an astronaut. I don't believe anyone is at fault for this."

FMI: www.nasa.gov