Polar relay system for satellite communication

Abstract

One of the preferred embodiments of the present invention is a telecommunications system that includes twelve satellites (S) which are equally deployed in four polar low Earth orbits (OR). A preferred embodiment provides a system for transmitting a message between two terminals (G) on the ground through a store-and-forward network. A first satellite (S1/OR1) traveling in a first polar orbit (OR1) receives and stores a message from a sending terminal (GA) on the surface of the Earth (E). As the first satellite (S1/OR1) passes over the North Pole (NP), it transmits the stored message from the sending terminal (GA) down to a relay station (GB) located near the North Pole (NP). The message is stored at this polar relay station (GB) until a second satellite (S1/OR2) moving in a second orbit (OR2) flies within range. At that time, the polar relay station (GB) sends the stored message up to the second satellite (S1/OR2), which stores the message and finally transmits it to a receiving terminal (GC) somewhere on the ground. This store-and-forward relay method takes advantage of the geometry of a system that employs more than one satellite which each operate in different polar orbits. The different polar orbits allow the satellites to fly over different parts of the globe frequently. The rotation of the Earth beneath the satellites allows every satellite in the system to fly over vast regions of the Earth's surface and, therefore, to communicate with a very large number of terminals located virtually anywhere in the world. The present invention provides a wide variety of communication systems without requiring costly and complex intersatellite links.