Microgravity Effects on Combustion of Polymers

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. Results indicate that qualifying upward flame propagation ground tests provided conservative results for the materials tested in microgravity by sustaining their combustion in less severe oxygen concentration and total pressure conditions than those in which extinguishment occurred in quiescent microgravity environments.