On 29-Jul-2005, "RBM" rbm2(remove wrote:

The truth of the matter is they already had a foam that performed perfectly
well with no problems, but stopped using it because it wasn't
"environmentally friendly"

While the replacement foam has flaking problems, that doesn't mean the previous
foam was "perfectly good". The old foam suffered more from problems with ice
than the latest incarnation. Ice can cause as much damage to the tiles as
can the foam.

The fact is that NASA has been relying on luck for a long time. Even going all
the way back to the Mercury program, the margin for error was always small.

Mike