Elliptical orbit satellite, system, and deployment with controllable coverage characteristics

• US 5,582,367 A
• Filed: 02/16/1994
• Issued: 12/10/1996
• Est. Priority Date: 06/02/1992
• Status: Expired due to Term

• Current Assignee: ESBH, Inc.
• Original Assignee: Mobile Communications, Inc.
• Inventors: Brosius, Jay, Castiel, David, Draim, John E.
• Primary Examiner(s): Kashnikow, Andres
• Assistant Examiner(s): MARQUIS, LISSI MOJICA
• Application Number:
  US08/197,260
• Time in Patent Office: 1,028 Days
• Field of Search: 244/158 R, 244/164, 342/355, 342/356, 342/357, 342/358, 455/12.1, 455/13.1
• US Class Current: 244/158.4
• CPC Class Codes: B64G 1/002 Launch systems
• CPC Class Codes: B64G 1/1007 Communications satellites
• CPC Class Codes: B64G 1/1085 Swarms and constellations
• CPC Class Codes: B64G 1/242 Orbits and trajectories
• CPC Class Codes: B64G 1/2423 Sun-synchronous orbits
• CPC Class Codes: H04B 7/18576 Satellite systems for providing narrowband data service to fixed or mobile stations, e.g. using a minisatellite, a microsatellite for selecting H04W
• CPC Class Codes: H04B 7/195 Non-synchronous stations

Abstract

A special set of elliptical satellite orbits are described which allow preferential coverage of one parameter over another. According to a first modification, the orbits are retrograde, and preferentially cover one geographical location or time of day as compared with another. A second modification uses prograde orbits and allows the apogee of the orbit to be offset a constant amount with respect to the sun, to thereby cover a different time of day relative to the others. According to a special preferred mode of the invention, the apogee is always pointing towards the sun.

Claims

1. A communication system, comprising:

a constellation of satellites in orbit around the earth, each defining an elliptical orbit which has orbital parameters to satisfy the equation ##EQU10## , where Ω

is the right ascension of an ascending node, and ω

is an argument of perigee, and wherein each of said satellites in orbit asymmetrically covers one parameter of coverage more than another in a way which is constant at all positions of the earth relative to the sun, and

a plurality of earth stations, each positioned on the earth, each including tracking equipment to track a motion of at least one of said satellites, and communication equipment to communicate with said at least one of said satellites.

2. A system as in claim 1, wherein said parameter of coverage is geographical location.

3. A system as in claim 2, wherein said elliptical orbit is retrograde.

4. A system as in claim 3, wherein said orbit is chosen such that dω

/dt approaches zero.

5. A system as in claim 4, wherein an inclination of said orbit is set to substantially 116°

.

6. A system as in claim 4, wherein an inclination of said orbit is set to substantially 115°

and 118°

.

7. A system as in claim 1, wherein said parameter of coverage is time of day.

8. A system as in claim 7, wherein said elliptical orbit is prograde.

9. A system as in claim 8, wherein an apogee of the elliptical orbit is always at a constant angle from an earth-sun line:

an inclination of the orbit is between 0 and 43 degrees, period is between 1.7 to 5.0 hours, and eccentricity is between 0.0002 to 0.56.

10. A system as in claim 8, wherein inclination is greater than 0.5°

.

11. A system as in claim 8, wherein inclination is greater than 10°

.

12. A system as in claim 8, wherein said orbit is inclined.

13. A system as in claim 1, having a period of three hours.

14. A system as in claim 1, wherein an ascending node of each of the satellites is either at noon or at midnight.

15. A system as in claim 1, wherein said constellation includes a first ring of satellites, each of which have noon ascending nodes, and a second ring of satellites, each of which have midnight ascending nodes.

16. A method of communicating with a satellite, comprising the steps of:

propelling said satellite into an elliptical orbit which has orbital parameters to satisfy the equation ##EQU11## , where Ω

is the right ascension of an ascending node, and ω

is an argument of perigee, and wherein said orbit has characteristics to asymmetrically cover one parameter of coverage more than another in a way which is constant relative to a position of the sun, all year round;

providing a ground station which tracks a position in the orbit where the satellite will be at any given time; and

communicating between the ground station and the satellite.

17. A method as in claim 16, wherein said parameter of coverage is a geographical location.

18. A method as in claim 16, wherein said propelling step propels said satellite into an elliptical retrograde orbit.

19. A method as in claim 18, wherein said orbit is chosen such that dω

/dt approaches zero.

20. A method as in claim 19, wherein said propelling step includes propelling said satellite into an orbit, an inclination of said orbit is set to substantially 116°

.

21. A method as in claim 19, wherein said propelling step includes propelling said satellite into an orbit whose inclination of said orbit is set to substantially 115°

and 118°

.

22. A method as in claim 16, wherein said parameter of coverage is time of day.

23. A method as in claim 22, wherein said elliptical orbit is prograde.

24. A method as in claim 23, wherein the apogee is always at a constant angle from the earth-sun line:

an inclination is between 0 and 43 degrees, period is between 1.7 to 5.0 hours, and eccentricity is between 0.0002 to 0.56.

25. A method as in claim 23, wherein said propelling step includes propelling said satellite into an orbit with an inclination that is greater than 0.5°

.

26. A method as in claim 23, wherein said propelling step includes propelling said satellite into an orbit with an inclination that is greater than 10°

.

27. A method as in claim 16, having a period of three hours.

28. A method as in claim 16, wherein said propelling step includes propelling said satellite into an inclined orbit.

29. A method as in claim 16 wherein an ascending node of each of the satellites is either at noon or at midnight.

30. A method as in claim 16, wherein there are a constellation of satellites which includes a first ring of satellites, each of which have noon ascending nodes, and a second ring of satellites, each of which have midnight ascending nodes.