NASA delays launch of historic moon mission

[VMA131Marine]

5. That's not what happened to Columbia

During launch a piece of spray on foam from the external tank attachment structure fell off and hit the leading edge of the wing. The wing leading edge is a carbon-carbon composite structure and quite thin; the shuttle did not use tiles there. Anyway, the piece of foam punched a significant hole in the carbon-carbon leading edge that, on re-entry, allowed hot plasma generated by the shuttle’s hypersonic flight to enter the wing structure and melt critical components and structures. The wing structure itself was mostly aluminium so it was destroyed quite rapidly once exposed to the high temperature gas.
NASA has never had another heat shield fail on its other manned missions from Mercury through Gemini to Apollo. Neither have the Soviets/Russians for that matter although they had two other reentry failures resulting in fatalities: an failed parachute deployment and valve leak that depressurised the spacecraft too soon and asphyxiating the crew.