Eccentricity control for geosynchronous satellites
View Patent ↗Eccentricity control for a geosynchronous satellite includes: setting initial conditions, duration, and schedule for the eccentricity control; defining a plurality of parameters including control loci for centroid, semi-major axis, semi-minor axis, uncontrolled eccentricity radius, right ascension of ascending node, and inclination, wherein the plurality of parameters are defined such that when the eccentricity control is applied, a mean geodetic longitude of the geosynchronous satellite is maintained within a predefined distance from a station longitude.
1. A method of eccentricity control for a geosynchronous satellite having a geosynchronous orbit and an orbit line of nodes, the method comprising:
setting a schedule for eccentricity control of the geosynchronous orbit using a two-dimensional eccentricity vector ellipse describing target eccentricity vector components over an annual period, each of the eccentricity vector components indicating a magnitude and direction for eccentricity vectors from the geosynchronous satellite to a perigee of the geosynchronous orbit;
defining a plurality of parameters for the two-dimensional eccentricity vector ellipse including
a centroid for a control locus, the control locus defining the target eccentricity vector components for the eccentricity vector ellipse in two-dimensional space,
a semi-major axis and a semi-minor axis of the control locus determining an elliptical shape of the two-dimensional eccentricity vector ellipse, the semi-major axis of the control locus aligning with the orbit line of nodes and defining a maximum natural uncontrolled eccentricity of the geosynchronous orbit; and
transmitting operational commands to the geosynchronous satellite for eccentricity control based on the schedule and the two-dimensional eccentricity vector ellipse, the operational commands defining maneuvers and inter-maneuver uncontrolled eccentricity coast segments to maintain a geodetic longitude of the geosynchronous satellite within a predefined distance from a station longitude.
2. The method of claim 1 , wherein the predefined distance is 50 milli-degrees.
3. The method of claim 1 , wherein the eccentricity control is an eccentricity-inclination-sun synchronous control.
4. The method of claim 1 , wherein the plurality of parameters comprises setting elements [h,k] of the centroid at zero micros.
5. The method of claim 1 , wherein defining the plurality of parameters comprises setting the semi-major axis of the control locus at 350 micros and the semi-minor axis of the control locus at 0 micros for a maximum compensation control using Node-Synchronous Station Keeping (NSSK).
6. The method of claim 1 , wherein defining the plurality of parameters comprises setting the semi-major axis at 350 micros and the semi-minor axis at 200 micros for a minimum fuel control using Orbit Analysis System/Eccentricity-Inclination-Synchronous-Station-Keeping (EISK) beginning-of-life (BOL) inclined orbit scenario.
7. The method of claim 1 , wherein defining the plurality of parameters comprises setting the semi-major axis at 200 micros and the semi-minor axis at 200 micros for a minimum fuel control using EISK middle-of-life (MOL) equatorial orbit scenario.
8. The method of claim 1 , wherein the geodetic longitude of the geosynchronous satellite is maintained within a predefined distance from a station longitude for a specified range of near-equatorial latitudes.
9. An apparatus for eccentricity control of a geosynchronous satellite having a geosynchronous orbit and an orbit line of nodes, the apparatus comprising:
means for setting a schedule for eccentricity control of the geosynchronous orbit using a two-dimensional eccentricity vector ellipse describing target eccentricity vector components over an annual period, each of the eccentricity vector components indicating a magnitude and direction for eccentricity vectors from the geosynchronous satellite to a perigee of the geosynchronous orbit;
means for defining a plurality of parameters for the two-dimensional eccentricity vector ellipse including
a centroid for a control locus, the control locus defining the target eccentricity vector components for the eccentricity vector ellipse in two dimensional space,
a semi-major axis and a semi-minor axis of the control locus determining an elliptical shape of the two-dimensional eccentricity vector ellipse, the semi-major axis of the control locus aligning with the orbit line of nodes and defining a maximum natural uncontrolled eccentricity of the geosynchronous orbit; and
means for transmitting operational commands to the geosynchronous satellite for eccentricity control based on the schedule and the two-dimensional eccentricity vector ellipse, the operational commands defining maneuvers and inter-maneuver uncontrolled eccentricity coast segments to maintain a geodetic longitude of the geosynchronous satellite within a predefined distance from a station longitude.
10. The apparatus of claim 9 , wherein the means for defining the plurality of parameters comprises
means for setting elements [h,k] of the centroid of the control locus at zero micros.
11. The apparatus of claim 9 , wherein the means for defining the plurality of parameters comprises
means for setting the semi-major axis of the control locus at 350 micros and the semi-minor axis of the control locus at 0 micros for a maximum compensation control using Node-Synchronous Station Keeping (NSSK).
12. The apparatus of claim 9 , wherein the means for defining the plurality of parameters comprises
means for setting the semi-major axis of the control locus at 350 micros and the semi-minor axis of the control locus at 200 micros for a minimum fuel control using Orbit Analysis System/Eccentricity-Inclination-Synchronous-Station-Keeping (EISK) beginning-of-life (BOL) inclined orbit scenario.
13. The apparatus of claim 9 , wherein the means for defining the plurality of parameters comprises
means for setting the semi-major axis of the control locus at 200 micros and the semi-minor axis of the control locus at 200 micros for a minimum fuel control using EISK middle-of-life (MOL) equatorial orbit scenario.
14. The apparatus of claim 9 wherein the geodetic longitude of the geosynchronous satellite is maintained within a predefined distance from a station longitude for a specified range of near-equatorial latitudes.
15. A non-transitory computer-readable storage medium storing a computer program for eccentricity control of a geosynchronous satellite having a geosynchronous orbit and an orbit line of nodes, the program comprising executable instructions that cause a computer to:
set a schedule for eccentricity control of the geosynchronous orbit using a two-dimensional eccentricity vector ellipse describing target eccentricity vector components over an annual period, each of the eccentricity vector components indicating a magnitude and direction for eccentricity vectors from the geosynchronous satellite to a perigee of the geosynchronous orbit;
define a plurality of parameters for the two-dimensional eccentricity vector ellipse including
a centroid for a control locus, the control locus defining the target eccentricity vector components for the eccentricity vector ellipse in two-dimensional space,
a semi-major axis and a semi-minor axis of the control locus determining an elliptical shape of the two-dimensional eccentricity vector ellipse, the semi-major axis of the control locus aligning with the orbit line of nodes and defining a maximum natural uncontrolled eccentricity of the geosynchronous orbit; and
transmit operational commands to the geosynchronous satellite for eccentricity control based on the schedule and the two-dimensional eccentricity vector ellipse, the operational commands defining maneuvers and inter-maneuver uncontrolled eccentricity coast segments to maintain a geodetic longitude of the geosynchronous satellite within a predefined distance from a station longitude.
16. The non-transitory computer-readable storage medium of claim 15 , wherein the executable instructions that cause the computer to define the plurality of parameters comprises executable instructions that cause the computer to
set elements [h,k] of the centroid of the control locus at zero micros.
17. The non-transitory computer-readable storage medium of claim 15 , wherein the executable instructions that cause the computer to define the plurality of parameters comprises executable instructions that cause the computer to
set the semi-major axis of the control locus at 350 micros and a control locus semi-minor axis at 0 micros for a maximum compensation control using Node-Synchronous Station Keeping (NSSK).
18. The non-transitory computer-readable storage medium of claim 15 , wherein the executable instructions that cause the computer to define the plurality of parameters comprises executable instructions that cause the computer to
set semi-major axis of the control locus at 350 micros and a control locus semi-minor axis at 200 micros for a minimum fuel control using Orbit Analysis System/Eccentricity-Inclination-Synchronous-Station-Keeping (EISK) beginning-of-life (BOL) inclined orbit scenario.
19. The non-transitory computer-readable storage medium of claim 15 , wherein the executable instructions that cause the computer to define the plurality of parameters comprises executable instructions that cause the computer to
set the semi-major axis of the control locus at 200 micros and a control locus semi-minor axis at 200 micros for a minimum fuel control using EISK middle-of-life (MOL) equatorial orbit scenario.
20. The non-transitory computer-readable storage medium of claim 15 , wherein the geodetic longitude of the geosynchronous satellite is maintained within a predefined distance from a station longitude for a specified range of near-equatorial latitudes.