Illustrative orbital applications of field directed propulsion

This paper studies the feasibility of using a new implementation of electrodynamic propulsion to change the inclination, right ascension of the ascending node, and argument of perigee for a spacecraft. Thrust in electrodynamic propulsion is the Lorentz force which results when electric current flows in a conductor segment placed in the Earth's magnetic field. Field directed propulsion is an implementation which uses multi-turn conductor loops onboard the spaceraft that are partially shielded to produce a net force. It offers the advantage of no propellant requirement on a relatively compact vehicle. Instantaneous and orbit average power demands are the primary considerations in sizing a field directed propulsion unit and the associated power supply and power processing units. An expression for the specific power is derived that is vehicle independent and is applicable to any maneuver. Acceleration profile and the associated current vector required t o accomplish an orbit element change are developed based on examination of force requirements in Lagrange's planetary equations. Results show field directed propulsion can be used to change either inclination or right ascension of the ascending node of a low-Earth polar orbit at a rate of approximately 0.4 degrees/day using an average specific power of 4 Watts/kilogram (W/kg). Field directed propulsion can also be used to offset the effects of the Earth's oblateness on the argument of perigee. For a 24-hour Molniya orbit at 90' inclination, the average specific power requirement is 3.4 W/kg. These average power levels are within the range of specific power which can be produced with current power technology.