Shuttle's Thermal Tiles Have History of Problems

Feb. 4 -- A day after Columbia's liftoff, NASA confirmed that a piece of loose foam insulation had damaged the shuttle, but engineers concluded it wouldn't fatally damage its critical thermal tiles, despite the tiles' long 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 disaster in 1986. They eventually found the tiles were not the cause of that crash.

"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 Michael Wiskerchen, a former NASA scientist, describing how damage at one point could spread along a line of tiles.

Even before Columbia was first lauched, 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 has learned that during a launch of Columbia in 1997, more than 100 damaged tiles were damaged when insulation foam from an external fuel tank flaked off and hit the tiles. A NASA report said the damage was so serious that the tiles had to be replaced.

Read the 1997 NASA post-flight inspection report.

It's the same scenario now being investigated with the Columbia but first described in a NASA report in 1990. The author of this report, Elisabeth Pate-Cornell, got an urgent call from NASA Sunday.