New Synchronous Orbits Using the Geomagnetic Lorentz Force

Abstract

The Lorentz-augmented orbits concept provides propellantless electromagnetic propulsion without a tether, using the interaction between an electrostatically charged satellite and the Earth's magnetic field to provide a useful thrust. New types of Earth-synchronous orbits are found from equations governing the motion of satellites experiencing the Lorentz force in orbit. The equations of motion for such a spacecraft are derived based on a simplified magnetic field model, in which the dipole is aligned with true north. For a polar-orbiting satellite, a constant electrical charge can create arbitrary changes in the right-ascension angle. This method allows for single-orbit repeat-groundtrack low-Earth-orbit satellites. Analytical expressions for changes in orbital elements due to Lorentz forces are verified by numerical simulation for the polar and equatorial cases. In the equatorial case, manipulation of the longitude of perigee by constant electrostatic charge is possible. Perigee movement also allows for the creation of an Earth-synchronous type of orbit. The case of a dipole field, for which the north pole is not aligned with true north, is also examined. Feedback control using only the Lorentz force for actuation is shown to stabilize this general case.