Response of Elastomer Seal Materials to Solid Rocket Exhaust Emissions

Abstract

To explore the effects of solid rocket motor emissions on spacecraft docking seals, a set of elastomer seals and sheet material were placed in the plume during an open-air ground-based test firing of one of NASA’s solid rocket jettison motors. The seal specimens were placed 86 ft (26.2 m) from the nozzle during an approximately 1.5 s firing outdoors. The conditions near the seals were generally hundreds of pounds per square foot of dynamic pressure and temperatures greater than 400°F (204°C) with high plume velocities. Worst-case flight conditions were imposed; however, high-altitude, near-vacuum conditions were not imposed. Thus, the chemistry, temperature, and pressures of the combustion products are expected to be slightly different compared to flight conditions. Because this was a ground-based test done outdoors, the specimens had the opportunity to be soiled by dusty winds, and it is possible contaminants on the seals may have come off after the firing and prior to examination and testing. The goal was to determine if exposure to the plume from the firing would physically damage the seals. Overall, the silicone-base elastomer seals were not measurably damaged by the emissions; leak rates were unaffected.