Inclined geosynchronous orbit spacecraft constellations

Patent metadata

Field	Value
Publication number	US-10889388-B2
Application number	US-201715441032-A
Country	US
Kind code	B2
Filing date	Feb 23, 2017
Priority date	Feb 26, 2016
Publication date	Jan 12, 2021
Grant date	Jan 12, 2021

Abstract

A constellation of Earth-orbiting spacecraft includes a first spacecraft disposed in a first orbit and a second spacecraft disposed in a second orbit. Each of the first orbit and the second orbit is substantially circular with a radius of approximately 42,164 km. The first orbit and the second orbit have a respective inclination with respect to the equator within a range of 5° to 20°. The first orbit has a first right ascension of ascending node (RAAN1) and the second orbit has a second RAAN (RAAN2) of approximately RAAN1+90°.

First claim

What is claimed is:

1. A constellation of Earth-orbiting spacecraft, the constellation comprising:
a first pair of spacecraft, the pair of spacecraft consisting of a first spacecraft disposed in a first orbit and a second spacecraft disposed in a second orbit, wherein:
the first spacecraft and the second spacecraft are each located at a substantially similar median first longitude and the constellation includes no other spacecraft located at the median first longitude;
each of the first orbit and the second orbit is a substantially circular geosynchronous orbit with a radius of approximately 42,164 km;
the first orbit and the second orbit have a respective inclination with respect to the equator within a range of 5° to 20°; and
the first orbit has a first right ascension of ascending node (RAAN1) and the second orbit has a second right ascension of ascending node (RAAN2) of approximately RAAN1+90°.

2. The constellation of claim 1 , wherein:
the constellation is configured such that the first spacecraft reaches a point of maximum northerly latitude at approximately the same time that the second spacecraft is crossing the equator moving northward.

3. The constellation of claim 1 , wherein the first orbit has a right ascension of ascending node (RAAN) of approximately 315° and the second orbit has a RAAN of approximately 45°.

4. The constellation of claim 1 , wherein each respective spacecraft transmits and/or receives RF signals only during periods of time when that respective spacecraft is at a latitude with magnitude greater than a safe latitude magnitude.

5. The constellation of claim 4 , wherein the safe latitude magnitude is approximately 7.5°.

6. The constellation of claim 4 , wherein the constellation is configured such that, at all times, at least one of the first spacecraft or the second spacecraft is at a latitude with magnitude greater than the safe latitude magnitude.

7. The constellation of claim 4 , wherein the constellation is configured to provide continuous communications services to regions having a latitude between 55° N and 55° S.

8. A method comprising:
executing a stationkeeping strategy for a constellation of Earth-orbiting spacecraft, wherein:
the constellation includes a first pair of spacecraft, the pair of spacecraft consisting of a first spacecraft disposed in a first orbit and a second spacecraft disposed in a second orbit;
the first spacecraft and the second spacecraft are each located at a substantially similar median first longitude and the constellation includes no other spacecraft located at the median first longitude;
each of the first orbit and the second orbit is a substantially circular geosynchronous orbit with a radius of approximately 42,164 km;
the first orbit and the second orbit have a respective inclination with respect to the equator within a range of 5° to 20° ;
a separation between a first right ascension of ascending node (RAAN 1 ) of the first orbit and a second right ascension of ascending node (RAAN 2 ) of the second orbit is approximately 90°; and
the stationkeeping strategy includes maintaining the separation at an approximately constant value of 90° while otherwise allowing RAAN 1 and RAAN 2 to drift.

9. The method of claim 8 , wherein:
the constellation is configured such that the first spacecraft reaches a point of maximum northerly latitude at approximately the same time that the second spacecraft is crossing the equator moving northward.

10. The method of claim 9 , wherein each respective spacecraft transmits and/or receives RF signals only during periods of time when that respective spacecraft is at a latitude with magnitude greater than a safe latitude magnitude.

11. The method of claim 10 , wherein the safe latitude magnitude is approximately 7.5°.

12. The method of claim 10 , wherein the constellation is configured such that, at all times, at least one of the first spacecraft or the second spacecraft is at a latitude with magnitude greater than the safe latitude magnitude.

13. The method of claim 10 , wherein the constellation is configured to provide continuous communications services to regions having a latitude between 55° N and 55° S.

14. A constellation of Earth-orbiting spacecraft, the constellation comprising:
a first plurality of spacecraft disposed in a first orbit and a second plurality of spacecraft disposed in a second orbit, wherein:
each of the first orbit and the second orbit is a substantially circular with a radius of approximately 42,164 km;
the first orbit and the second orbit have a respective inclination with respect to the equator within a range of 5° to 20°;
a first spacecraft of the first plurality of spacecraft and a second spacecraft of the second plurality of spacecraft are each located at a substantially similar first median longitude and the constellation includes no other spacecraft located at the median first longitude; and
the first orbit has a first right ascension of ascending node (RAAN1) and the second orbit has a second RAAN (RAAN2) of approximately RAAN1+90°.

15. The constellation of claim 14 , wherein:
a third spacecraft of the first plurality of spacecraft in the first orbit and a fourth spacecraft of the second plurality of spacecraft disposed in the second orbit are each located at a substantially similar second median longitude that is substantially different from the first median longitude.

16. The constellation of claim 15 , wherein:
a fifth spacecraft of the first plurality of spacecraft in the first orbit and a sixth spacecraft of the second plurality of spacecraft disposed in the second orbit are each located at a substantially similar third median longitude.

17. The constellation of claim 16 , wherein the first median longitude, the second median longitude and the third median longitude are spaced apart by approximately 120°.

18. The constellation of claim 16 , wherein the constellation is configured to provide global continuous communications services to regions having a latitude between 55° N and 55° S.

19. The constellation of claim 14 , wherein the first orbit has a right ascension of ascending node (RAAN) of approximately 315° and the second orbit has a RAAN of approximately 45°.

20. The constellation of claim 14 , wherein each respective spacecraft communicates with the ground only during periods of time when that respective spacecraft is at a latitude with magnitude greater than a safe latitude magnitude.

Assignees

• Space Systems/Loral LLC

Inventors

• Turner Andrew E

Classifications

• B64G1/1085 Primary

  Swarms and constellations · CPC title

• B64G1/40

  Arrangements or adaptations of propulsion systems · CPC title

• B64G1/411

  Electric propulsion · CPC title

• B64G1/2425

  Geosynchronous orbits · CPC title

• B64G1/1007 Primary

  Communications satellites · CPC title