New Synchronous Orbits Using the Geomagnetic Lorentz Force

Abstract

Repeat groundtrack orbit is any orbit whose sub-satellite point traces out a recurring pattern in some integer numbers of orbits. Traditionally, these orbits are achieved by adjusting the period of a satellite such that it completes an integer number of orbits in exactly an integer number of sidereal Earth days. Geostationary and Geosynchronous orbits are perhaps the most familiar and useful examples. These orbits have a mean motion equal to the spin rate of the Earth. We shall refer to orbits that repeat their groundtrack every orbit as GT-1 orbits. Thus all GEO orbits are in the GT-1 class. We define a general notation of a GT-x class orbit repeats its groundtrack every x orbits. For example, satellites in the GPS constellation are in 12 sidereal hour orbits, and can thus be considered GT-2 satellites. Many LEO imaging satellites designed for full-Earth coverage also use repeat track orbits. Landsat 7 covers the full Earth every 233 orbits making it a GT-233 satellite: every 16 days, the satellite completes exactly 233 orbits.1 Dedicated weather satellites and both government and commercial communications satellites are just a few of the numerous uses for GT-1 orbits. However GT-1 systems are currently limited to GEO orbits. The altitude of these satellites, roughly 36000km, requires high-power communications and impacts the aperture requirements for Earth-imaging satellites. An ideal arrangement would be a GT-1 orbit at a low Earth altitude. We propose a method of obtaining a low Earth, polar GT-1 orbit with the help of a new propellantless propulsion concept called Lorentz Augmented Orbits (LAO). The Lorentz force experienced by a particle of charge q (Coulombs) moving through a magnetic field ~ B