Satellite System

Abstract

A satellite system operates at altitudes between 100 and 350 km relying on vehicles including a self-sustaining ion engine to counteract atmospheric drag to maintain near-constant orbit dynamics. The system operates at altitudes that are substantially lower than traditional satellites, reducing size, weight and cost of the vehicles and their constituent subsystems such as optical imagers, radars, and radio links. The system can include a large number of lower cost, mass, and altitude vehicles, enabling revisit times substantially shorter than previous satellite systems. The vehicles spend their orbit at low altitude, high atmospheric density conditions that have heretofore been virtually impossible to consider for stable orbits. Short revisit times at low altitudes enable near-real time imaging at high resolution and low cost. At such altitudes, the system has no impact on space junk issues of traditional LEO orbits, and is self-cleaning in that space junk or disabled craft will de-orbit.

What is claimed is: 
     
         1 . A satellite network comprising a plurality of satellites arranged in an orbit having an altitude between 100 km and 350 km, wherein each satellite of the plurality of satellites comprises:
 a system configured to:
 ingest ambient air particles; 
 transform the ambient air particles via a thermalizing, concentrating and slowing process; and 
   an ion engine configured to:
 ingest the transformed air particles; 
 ionize the transformed air particles; and 
 generate thrust from the ionized transformed air particles sufficient to maintain the orbit of the satellite. 
   
     
     
         2 . The satellite network as defined in  claim 1 , wherein each satellite of the constellation of satellites is configured to at least one of:
 neutralize ionized transformed air particles downstream of the vehicle; and   eject excess electrons.   
     
     
         3 . The satellite network as defined in  claim 1 , wherein each system comprises an inlet configured to:
 ingest the ambient air particles as the satellite moves in orbit; and   thermalize, concentrate, and slow the ambient air particles.   
     
     
         4 . The satellite network as defined in  claim 3 , wherein one or more surfaces of the system comprise a material selected to be smooth relative to the size of the ambient air particles such that tailored focusing of the ambient air particles is achieved. 
     
     
         5 . The satellite network as defined in  claim 4 , wherein the material is sapphire. 
     
     
         6 . The satellite network as defined in  claim 3 , wherein one or more surfaces of the system comprise a material selected to transfer kinetic energy from the ambient air particles and to direct a portion of the ambient air particles into the inlet. 
     
     
         7 . The satellite network as defined in  claim 6 , wherein the material is selected based on particle scattering properties and is placed such that tailored focusing and thermalization of the ambient air particles is achieved. 
     
     
         8 . The satellite network as defined in  claim 6 , wherein the material is selected based on catalytic properties for converting O into O 2  and placed such that tailoring the amount of O and O 2  entering the ion engine is achieved. 
     
     
         9 . The satellite network as defined in  claim 1 , wherein the system is configured to decrease an average velocity of ambient air particles by at least two orders of magnitude and increase the pressure of the ambient air particles by at least one order of magnitude. 
     
     
         10 . The satellite network as defined in  claim 1 , each satellite further comprising a controller configured to:
 determine spatial information indicative of at least one of a current altitude of the satellite, an orientation of the satellite relative to a terrestrial surface, and a position of the satellite relative to at least one other satellite;   compare a current altitude of the satellite against a desired altitude; and   control the ion engine to generate thrust sufficient to achieve the desired altitude.   
     
     
         11 . The satellite network as defined in  claim 1 , each satellite further comprising a solar energy collection system to provide power to the ion engine and one or more components of the satellite. 
     
     
         12 . The satellite network as defined in  claim 1 , each satellite further comprising one or more sensors to determine the current altitude of the satellite. 
     
     
         13 . The satellite network as defined in  claim 1 , each satellite further comprising a radio transmitter and receiver to communicate with at least one of an airborne, a shipborne and a terrestrial based radio communication system. 
     
     
         14 . The satellite network as defined in  claim 13 , wherein each radio transmitter and receiver comprises a fixed antenna pattern. 
     
     
         15 . The satellite network as defined in  claim 1 , wherein the plurality of satellites occupy a first orbital plane, the satellite network further comprising a second plurality of satellites that occupy a second orbital plane different from the first orbital plane. 
     
     
         16 . The satellite network as defined in  claim 15 , wherein the first and second orbital planes comprise at least 45 satellites in each plane. 
     
     
         17 . The satellite network as defined in  claim 15 , wherein there are more than six orbital planes. 
     
     
         18 . The satellite network as defined in  claim 1 , each satellite further comprising a laser-based communication system configured to transmit information to and receive information from another laser-based communication system of another satellite. 
     
     
         19 . A satellite configured to orbit a terrestrial surface at an altitude between 100 km and 350 km, the satellite comprising:
 a system with an inlet to thermalize, concentrate and slow incoming ambient air particles; and   an ion engine configured to ingest and ionize the thermalized, concentrated, and slowed air particles and generate thrust from the ionized thermalized, concentrated, and slowed air particles sufficient to maintain the orbit of the satellite.   
     
     
         20 . A method of generating thrust in a self-sustaining low earth orbit satellite, the method comprising:
 ingesting ambient air particles by a system configured to slow the ambient air particles by at least two orders of magnitude and to concentrate the ambient air particles by at least one order of magnitude within said satellite;   ionizing the slowed and concentrated air particles by an ion engine; and   accelerating the ionized slowed and concentrated air particles through an ejection port of said satellite to generate thrust.