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Candidate materials for spacecraft crew compartments must pass flammability tests conducted according to NASA-STD-6001 Test 1. The test is conducted on the ground, and there is uncertainty on how flammability data obtained under these conditions would predict materials flammability in microgravity. NASA Glenn Research Center conducted a cooperative program with the Russian Space Agency Keldysh Research Center, with technical support provided by NASA Johnson Space Center White Sands Test Facility, to investigate polymer combustion in ventilated microgravity in a small combustion tunnel operated on the Orbital Station Mir. It was found that very low forced convective flows can sustain polymer combustion in microgravity. Shutoff of the flow, however, is likely to suppress combustion.

Limiting oxygen index (LOI) is commonly used to evaluate flammability of polymers. The accepted test standards are ASTM G 125 and D 2863. The data provided by these standards, however, may not correlate closely with many real-life fire scenarios. Two of the most common issues are the direction of flame propagation recommended by the standard method and the test environment temperature. The standard test methods recommend testing samples at room temperature and in a downward flame propagation mode. Modifications of these two parameters could render most polymers flammable; however, these same polymers would, under standard testing conditions set forth by ASTM G 125 and D 2863, be considered nonflammable. In this study, standard and modified LOI tests were conducted on 16 polymers to determine the magnitude of these effects. The results indicate that the LOI data commonly presented in the literature should be used with caution.