Columbia tragedy: High-temperature materials chemistry and thermodynamic considerations of the breached wing leading edge

Metallurgical analysis of debris from the leading edge of the breached left wing of the Columbia space shuttle demonstrated that the temperatures inside the leading edge structural subsystem exceeded 1760 °C (3200 °F). A thin, relatively uniform deposit containing aluminum, Inconel, and Cerachrome was found inside most of the reinforced carbon-carbon composite panels. Such deposition indicates the melting and concurrent deposition of spar, attachment hardware, and insulation. In contrast, panel 8 showed thick, nonuniform deposits suggesting this panel was the breach location. The characteristics of these nonuniform deposits provided indications of plasma flow direction and plasma impingement locations and were helpful in establishing the sequence of failure events. In addition, no indications of A286 were found in the deposits inside panel 8. The lack of evidence for A286 suggests that the breach location was remote from the A286 fittings. This article is based on a presentation given on October 19, 2004, at the session on “The Space Shuttle Columbia: A Forensic Materials Perspective” as part of the Failure Analysis and Prevention Symposium at ASM International’s Materials Solutions Conference and Exposition in Columbus, Ohio.