TAP Orbit Stationkeeping via RAAN Drift and Indirect ARGP Control
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Solution Overview
Problem
Satellites in Three APogee (TAP) orbits experience significant natural drift due to gravitational influences, requiring substantial propellant mass for annual orbit maintenance to maintain desired orbital parameters, especially inclination, argument of perigee, perigee altitude, and apogee altitude, which is costly and inefficient over a 10-15 year mission life.
Innovation Solution
A stationkeeping strategy that controls the operational orbit by selecting an initial Right Ascension of Ascending Node (RAAN) to naturally drift to zero at mid-life, and indirectly controlling Argument of Perigee, apogee altitude, and perigee altitude through orbit maintenance maneuvers, reducing the need for inclination control and minimizing propellant usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional orbit maintenance maneuvers are performed to control inclination, argument of perigee, perigee altitude, and apogee altitude, then orbital parameters are maintained within desired ranges, but total impulse and propellant mass requirements become very significant over 10-15 year mission life
Solution Approach 1:
The patent changes the approach from actively controlling all orbital parameters to allowing natural drift of inclination and argument of perigee, while maintaining only perigee and apogee altitudes within acceptable ranges. This parameter change reduces the number of controlled variables and consequently the propellant mass required for stationkeeping maneuvers over the mission lifetime.
Solution Approach 2:
Instead of performing complete orbit maintenance maneuvers to control all four parameters (inclination, argument of perigee, perigee altitude, apogee altitude), the patent applies partial action by controlling only the critical altitude parameters and allowing natural evolution of the other parameters, thereby reducing the total impulse and propellant consumption.
2Reliability
If frequent orbit maintenance maneuvers are conducted to compensate for gravitational drift, then desired orbital parameters are maintained, but mission efficiency decreases and propellant consumption increases
Solution Approach 1:
The patent modifies the stationkeeping strategy by changing which parameters are actively controlled versus which are allowed to drift naturally. This parameter change reduces the frequency and magnitude of maintenance maneuvers, improving mission efficiency while maintaining sufficient orbital stability for the intended application.
Solution Approach 2:
The patent allows the orbital inclination and argument of perigee to evolve naturally without active intervention, utilizing the Earth's gravitational field and natural orbital dynamics to maintain these parameters within acceptable ranges, thereby reducing the need for propellant-consuming correction maneuvers.
3Reliability
If active control of argument of perigee is implemented, then orbital coverage requirements are met, but additional propellant mass is required beyond what is needed for altitude control alone
Solution Approach 1:
The patent changes the control strategy from actively maintaining argument of perigee to allowing it to drift naturally, relying on the coupled evolution of inclination and argument of perigee to maintain adequate polar coverage. This reduces propellant mass requirements while preserving the essential coverage capability.
Solution Approach 2:
The patent utilizes the natural coupling between inclination and argument of perigee drift, where the simultaneous evolution of both parameters provides sufficient polar coverage without requiring active control of argument of perigee, thereby achieving multi-functionality through natural orbital dynamics.
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 strategy significantly reduces the total impulse required for orbit maintenance, allowing for reduced propellant mass and extended periods without maintenance maneuvers, thereby enhancing the efficiency and longevity of satellite coverage in polar regions.
Implementation Method 1
a satellite initially disposed in a TAP orbit described above will experience considerable natural drift from desired parameters of amount of orbit inclination, argument of perigee, perigee and apogee altitude as a result of gravitational influence of the Earth, moon and sun
Data Source
AI summary
A stationkeeping strategy for a satellite disposed in a TAP orbit includes controlling parameters of the orbit such that, for a constellation of two satellites disposed in the orbit, the constellation provides substantially continuous coverage of a polar region. The stationkeeping strategy includes one or more of: establishing an initial Right Ascension of Ascending Node (RAAN) of the operational orbit such that naturally caused orbital drift results in a mid-life RAAN of approximately 0 degrees (360 degrees); and controlling Argument of Perigee (ARGP), only indirectly, by performing orbit maintenance maneuvers only to directly control one or more of the operational orbit apogee altitude, the operational orbit perigee altitude, and inclination within a respective required range.