Did NASA Ignore Damage to Columbia?

NASA managers handling the doomed Columbia flight were "professionally irresponsible" in dealing with damage reports early in the mission, a member of the presidential commission that investigated the Challenger disaster 17 years ago told ABCNEWS.

John Macidull strongly questions why NASA never ordered a telescopic scan of the underside of the damaged Columbia during its 16-day mission, even after engineers became aware insulation foam from the fuel tank had struck the heat tiles. Damage to the tiles is the leading theory as to what caused the shuttle to break up Saturday over Texas, killing all seven astronauts on board.

An Air Force telescope in New Mexico did take such photos, but it was only after the accident that NASA sought them.

"I just find it hard to believe that they didn't thoroughly check with every means available to see how much damage may have been done," said Macidull.

NASA engineers at Mission Control concluded the damage posed no threat and that there was no reason to take special precautions.

"Through analysis and our ability to call back on our experience with tile, it was judged that that event did not represent a safety concern," said shuttle project manager Ron Dittemore.

Macidull said that was "wishful thinking," and that NASA has not changed the way it deals with safety problems.

"How could you make a judgment on whether something is critical or dangerous, whether some kind of damage is critical or dangerous, if you don't know exactly what the damage is? And then you don't try to find out?" said Macidull.

NASA Engineer: Tile Damage Was Serious

NASA engineers have told ABCNEWS the agency knew, or should have known, of the extensive tile damage discovered on the Columbia after a 1997 flight, when a new kind of insulation foam came off the fuel tank and caused serious damage to more than 100 heat-shield tiles.

NASA engineer Greg Katnik wrote in a NASA report that the damage was so serious that the tiles had to be replaced.

Read the 1997 NASA post-flight inspection report.

"When we see that kind of damage on any orbiter, we know that we have a problem happening somewhere," said Katnik, who said he tracked the problem to the new kind of foam.

That foam — still in use today — was designed to be environmentally friendly, but created another set of problems, Katnik said.

"However, the foam composition changed ever so slightly … and would cause little air pockets to form, which would expand at altitude and pop the foam off. We actually called it popcorning, because it looked like little bits of popcorn coming off," he said.

It's the same scenario now being investigated in the Columbia tragedy.

Some changes were ordered, but NASA has now impounded the records at a Lockheed-Martin facility outside New Orleans where the foam insulation is applied to the external fuel tanks.

NASA engineers say the foam, just like raindrops, can turn into powerful projectiles at the high speeds the shuttle reaches at liftoff.

Shuttle’s Thermal Tiles Have History of Problems

For years, NASA has been warned about the shuttle's heat-shield tiles. The space agency extensively studied the problem shortly after the Challenger explosion in 1986. They eventually found the tiles were not the cause of that disaster.

"What we discovered is that there could be an effect where this starts here and it just moves back to the rest of the tiles and you could get kind of like a zipper," said former NASA scientist Michael Wiskerchen, describing how damage at one point could spread along a line of tiles.

Even before Columbia was first launched, it lost more than 2,000 of its tiles as it was being ferried to Florida on the back of an airplane in 1979.

"We had to look at how we manufactured the glue, and how we put it on and the process that went into it," Wiskerchen said.

Then, after a two-year delay to fix the tiles, the Columbia was finally launched in 1981. Despite all of the work that was done during the delay, Columbia still lost 15 tiles during the blastoff.

And on almost every shuttle flight since, there has been some kind of problem with the tiles, although never in critical areas.

"You could actually get a burn-through in some regions and still land safely, and you could just go repair the burn-through place. So it is very critical as to where it happens and how it happens," Wiskerchen said.

ABCNEWS' Rhonda Schwartz, Vic Walter and Teri Whitcraft contributed to this report.