Two Years After Columbia, Some Blunt Language From RTF Task
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
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
"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
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."