Applications of first generation engines

Communication Satellites

The true value of an electric propulsion system without propellant becomes apparent when long duration science missions are considered. The following table gives a comparison of propulsion system performance originally specified for the recently completed ESA Smart 1 mission.

The 15 year thrust period is based on the cathode life of the magnetron. This will be the same technology as that used in space qualified TWTA’s, which are currently specified for 15 years continuous operation.

If the 700 W (dc) engine was used as primary propulsion for a 50 kg science probe, a velocity increment of 5.6 km/sec would be achieved in the first year for a thrust of 88 mN. Thereafter, due to the effects of equation 2, the thrust falls as the velocity increases, until after 15 years, the thrust would be 16 mN at a terminal velocity approaching 30 km/sec.