Node-Synchronous Eccentricity Control for Inclined Synchronous Orbits
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Solution Overview
Problem
Maintaining the position of satellites in inclined synchronous orbits is challenging due to the difficulty in controlling eccentricity, which leads to significant fuel consumption and interference issues, especially with solar forces affecting satellites in geostationary and geosynchronous orbits.
Innovation Solution
The method involves averaging the right ascension of the ascending node and managing the eccentricity vector to be substantially collinear with the inclination vector, using thrusters to apply velocity increments 180 degrees apart along the orbit, thereby minimizing fuel consumption and maintaining precise longitude control within narrow slot constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sun-synchronous eccentricity control is used, then eccentricity is compressed, but fuel consumption increases and longitude control precision decreases
Solution Approach 1:
The patent implements dynamic eccentricity control by adjusting the eccentricity vector orientation to remain perpendicular to the position vector from Earth to satellite. This dynamic adjustment allows the satellite to maintain precise longitude control while reducing the magnitude of corrective maneuvers needed, thereby decreasing fuel consumption compared to static sun-synchronous control methods
Solution Approach 2:
The patent changes the control parameter from sun-synchronous orientation to node-synchronous orientation, where the eccentricity vector is oriented perpendicular to the position vector rather than perpendicular to the sun vector. This parameter change optimizes the control strategy for inclined synchronous orbits, achieving better longitude precision with reduced ΔV requirements
2Device complexity
If single burn sun-synchronous perigee station keeping is used, then maneuver complexity is reduced, but eccentricity becomes difficult to control and slot width is exceeded
Solution Approach 1:
The patent segments the station-keeping maneuver into two burns: a primary burn at perigee for eccentricity control and a secondary burn for longitude adjustment. This segmentation allows independent optimization of each maneuver component, achieving precise eccentricity control while maintaining overall maneuver simplicity
Solution Approach 2:
The patent performs preliminary eccentricity control at perigee before the satellite reaches the equatorial crossing points. By addressing eccentricity corrections in advance at perigee, the satellite arrives at the slot region with minimized longitudinal excursion, reducing the need for large corrective burns later
3Adaptability or versatility
If inclined synchronous orbit is used for mobile communications, then communication coverage is improved, but interference issues increase due to slot constraints
Solution Approach 1:
The patent implements feedback control by continuously monitoring the satellite's longitude position and eccentricity vector orientation. Based on this feedback, the control system adjusts the timing and magnitude of station-keeping maneuvers to maintain the satellite within its assigned slot, preventing interference with adjacent satellites while preserving inclined orbit benefits
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces fuel consumption by approximately 36% compared to traditional sun-synchronous eccentricity control methods, allowing for more precise longitude control and extended station keeping life, while minimizing the impact of solar forces on satellite orbits.
Implementation Method 1
correcting the orbit of the satellite by applying velocity increments 180 degrees apart along the orbit with a thruster mechanism
Implementation Method 2
The principal forces which disturb a spacecraft's position are generated by the gravity of the sun and the moon, the Earth's elliptical shape (triaxiality) and solar radiation pressure
Implementation Method 3
The principal forces which disturb a spacecraft's position are generated by the gravity of the sun and the moon
Data Source
AI summary
A method for performing east-west station keeping for a satellite in an inclined synchronous orbit is described. The method includes averaging a value of a right ascension of the ascending node for an inclination vector associated with the satellite over a period of the control cycle, and managing corrections for the satellite such that an eccentricity vector, directed at perigee, is substantially collinear with the inclination vector.