Resistojet rocket

A resistojet is a method of spacecraft propulsion (electric propulsion) that provides thrust by heating a (typically non-reactive) fluid. Heating is usually achieved by sending electricity through a resistor consisting of a hot incandescent filament, with the expanded gas expelled through a conventional nozzle.

Resistojets have been flown in space since 1965 on board military Vela satellites. However, they only became used in commercial applications in 1980 with the launch of the first satellites in the INTELSAT-V program. Many GEO spacecraft, and all 95 Iridium, used Aerojet MR-501/MR-502 series resistojet engines. Nowadays resistojet propulsion is used for orbit insertion, attitude control, and deorbit of LEO satellites, and do well in situations where energy is much more plentiful than mass, and where propulsion efficiency needs to be reasonably high but low thrust is acceptable.

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