Two-Stage (Resistojet/ion Motor) Transfer of Communications Satellites.

Abstract : Thruster exhaust velocities between 9 km/s and 18 km/s are shown to be attractive for transferring communications satellites to synchronous orbit. No available thruster has an exhaust velocity in this range, but two-stage transfer using hydrogen resistojets (velocities less than 9 km/s) and mercury ion motors (velocities greater than 18 km/s) could provide equivalent performance, the equivalent exhaust velocity being related to the altitude of the orbit of switchover from resistojets to ion motors. Moreover, the equivalent efficiencies obtained could be quite high. In particular, it is shown that a resistojet/ion motor system combined with a thrust-augmented Delta launch vehicle could transfer a 583 kg 10 kW satellite to synchronous orbit in two and a half months. (Author)