System for maintaining satellites in orbital configuration
A constellation of many satellites are actively maneuvered to maintain specified non-geosynchronous reference orbits. Each satellite is assigned a slot within a particular reference orbit. For each reference orbit, a set of orbital parameters including eccentricity and argument of perigee for frozen orbits are selected that are unique relative to other reference orbits in use. One characteristic of a frozen orbit is that at a given point in the orbit, altitude is relatively constant. At points where orbital planes of the reference orbits intersect, the differing sets of orbital parameters assure a vertical separation between satellites in different orbital planes is maintained without the need for evasive maneuvers. Actual orbital motion data is obtained from sensors onboard each satellite. The desired orbital parameters are maintained based on the actual orbital motion data as part of scheduled maneuvers to maintain the reference orbit assigned to that satellite.
1. A method of controlling satellites, the method comprising:
determining a first set of orbital parameters comprising:
a first eccentricity value,
a first argument of perigee value, and
a first right ascension of the ascending node (RAAN) value;
determining a second set of orbital parameters comprising:
a second eccentricity value,
a second argument of perigee value, and
a second RAAN value;
placing a first satellite into a first orbit corresponding to the first set of orbital parameters, wherein the first orbit is a frozen orbit;
placing a second satellite into a second orbit corresponding to the second set of orbital parameters, wherein the second orbit is a frozen orbit;
determining first position data of the first satellite;
determining second position data of the second satellite;
determining a first set of maneuvering instructions based at least in part on the first position data and the first set of orbital parameters;
determining a second set of maneuvering instructions based at least in part on the second position data and the second set of orbital parameters;
based at least in part on the first set of maneuvering instructions, maneuvering the first satellite to within (i) a first threshold value of the first eccentricity value, (ii) a second threshold value of the first argument of perigee value, and (iii) a third threshold value of the first RAAN value; and
based at least in part on the second set of maneuvering instructions, maneuvering the second satellite to within (iv) a fourth threshold value of the second eccentricity value, (v) a fifth threshold value of the second argument of perigee value, and (vi) a sixth threshold value of the second RAAN value.
2. The method of claim 1 , wherein:
the first orbit is at a first altitude above a first latitude;
the second orbit is at a second altitude above the first latitude; and
the first altitude and the second altitude are separated by at least a first distance.
3. The method of claim 1 , wherein:
the first orbit is at a first altitude above a first latitude, wherein the first latitude is between +75 degrees North and −75 degrees South,
the second orbit is at a second altitude above the first latitude, and
the first altitude and the second altitude are separated by at least a first distance.
4. The method of claim 1 , further comprising:
determining a third set of orbital parameters indicative of a frozen orbit, the third set of orbital parameters comprising:
a third eccentricity value,
a third argument of perigee value, and
a third RAAN value;
wherein:
the first argument of perigee value is within a seventh threshold value of the third argument of perigee value; and
the second argument of perigee value is within the seventh threshold value of the third argument of perigee value.
5. The method of claim 1 , wherein:
the first set of orbital parameters describe a first line of apsis,
the second set of orbital parameters describe a second line of apsis, and
the first line of apsis and the second line of apsis are not coaligned.
6. The method of claim 1 , wherein the first satellite has a first time of perigee passage; and further comprising:
placing a third satellite into the first orbit corresponding to the first set of orbital parameters, wherein the third satellite has a second time of perigee passage that is different from the first time of perigee passage.
7. The method of claim 1 , wherein:
the first set of orbital parameters are based on capabilities of a maneuvering system of the first satellite; and
the second set of orbital parameters are based on capabilities of a maneuvering system of the second satellite.
8. A system comprising:
a first satellite in a constellation of satellites, the first satellite comprising:
a first set of sensors; and
a first maneuvering system;
a first control system to:
receive first position data acquired using the first set of sensors;
retrieve a first set of orbital parameters comprising:
a first reference orbit comprising:
a first eccentricity value,
a first argument of perigee value, and
a first right ascension of the ascending node (RAAN) value,
wherein a first altitude of the first satellite in the first reference orbit at a first latitude differs by at least a threshold distance from any other reference orbits used by the constellation; and
a first ti me of perigee passage,
determine, based on the first position data and the first set of orbital parameters, a first set of maneuvering instructions;
send to the first maneuvering system the first set of maneuvering instructions; and
wherein the first maneuvering system operates based on the first set of maneuvering instructions.
9. The system of claim 8 , wherein the first latitude is between +75 degrees North and −75 degrees South.
10. The system of claim 8 , wherein the first reference orbit and the other reference orbits comprise frozen orbits.
11. The system of claim 8 , wherein:
the first reference orbit has a first line of apsis, and
a second line of apsis for any of the other reference orbits is not coaligned with the first line of apsis.
12. The system of claim 8 , wherein the first time of perigee passage differs from a second time of perigee passage of a second satellite in the first reference orbit.
13. A method performed by a first satellite in a constellation of satellites, the method comprising:
determining first position data based on one or more sensors of the first satellite in the constellation;
retrieving a first set of orbital parameters comprising:
a first reference orbit of the constellation comprising:
a first eccentricity value,
a first argument of perigee value,
a first right ascension of the ascending node (RAAN) value,
wherein a first altitude of the first satellite in the first reference orbit at a first latitude differs by at least a first distance from any other reference orbits used by the constellation; and
a first time of perigee passage,
determining, based on the first position data and the first set of orbital parameters, a first set of maneuvering instructions; and
based on the first set of maneuvering instructions, maneuvering the first satellite to within a first threshold value of the first eccentricity value, a second threshold value of the first argument of perigee value, and a third threshold value of the first RAAN value.
14. The method of claim 13 , wherein the first latitude is between +75 degrees North and −75 degrees South.
15. The method of claim 13 , wherein the first reference orbit and the other reference orbits comprise frozen orbits.
16. The method of claim 13 , wherein:
the first reference orbit has a first line of apsis, and
a second line of apsis for any of the other reference orbits is not coaligned with the first line of apsis.
17. The method of claim 13 , wherein the first time of perigee passage differs from a second time of perigee passage of a second satellite in the first reference orbit.
18. The method of claim 13 , further comprising:
determining the first set of orbital parameters based on capabilities of a maneuvering system of the first satellite.
19. The method of claim 13 , further comprising:
determining a first portion of the first reference orbit that is within a fourth threshold value of the first argument of perigee value; and
wherein the maneuvering occurs within the first portion of the first reference orbit.
20. The system of claim 8 , the first control system to:
determine a first portion of the first reference orbit that is within a threshold value of the first argument of perigee value; and
wherein the first maneuvering system operates, based on the first set of maneuvering instructions, within the first portion of the first reference orbit.