High temperature thruster technology for spacecraft propulsion

Abstract

A technology program has been underway since 1985 to develop high temperature oxidation-resistant thrusters for spacecraft applications. The successful development of this technology will provide the basis for the design of higher performance satellite engines with reduced plume contamination. Alternatively, this technology program will provide a material with high thermal margin to operate at conventional temperatures and provide increased life for refuelable or reusable spacecraft. The new chamber material consists of a rhenium substrate coated with iridium for oxidation protection. This material increases the operating temperature of thrusters to 2200°C, a significant increase over the 1400°C of the silicide-coated niobium chambers currently used. Stationkeeping class 22 N engines fabricated from iridium-coated rhenium have demonstrated steady state specific impulses 20 to 25 seconds higher than niobium chambers. Ir-Re apogee class 440 N engines are expected to deliver an additional 10 to 15 seconds. These improved performances are obtained by reducing or eliminating the fuel film cooling requirements in the combustion chamber while operating at the same overall mixture ratio as conventional engines. The program is attempting to envelope flight qualification requirements to reduce the potential risks and costs of flight qualification programs.