Part 8: Shuttle Parachute Problems – Poor Heat Resistance
The parachute is attached to ACES
One of the outcomes of the Apollo 1 disaster was a change from nylon to flame-resistant suits for astronauts. The outer layer of the Advanced Crew Escape Suit (ACES) was flame-resistant Nomex. The intended purpose was to protect against a brief exposure to fire, to allow escape.
The outer covering of the parachute pack was Nomex, but the parachute harness was nylon webbing. (The astronauts’ boots, worn over ACES, were also partially made of nylon.) The Columbia Crew Survival Investigation Report notes that nylon loses strength about 250°F (121°C) and melts at 500°F (204°C), while Nomex decomposes at 932°F (500°C). It is very odd to use nylon together with a flame resistant material. This is not permitted for personal protective equipment (PPE) in the Alberta petroleum industry, for example.
Analysis of the helmets revealed that they were exposed to a temperature between 572°F (300°C) and 735°F (391°C) during deceleration. Within this temperature range, the helmets were damaged, but still functional. ACES would also have maintained integrity. However, it seems that if an astronaut were to have bailed out of Columbia, the parachute harness would have failed.
