Satellite Longitude Drift Control with Quasi-Continuous Thruster Phasing
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Solution Overview
Problem
Current methods for managing geosynchronous satellite longitudinal drift require ion thrusters to be fired for longer durations due to electric power limitations and long-arc ΔV losses, necessitating frequent small-ΔV firings for station keeping, which is inefficient.
Innovation Solution
A satellite longitude and drift control method using continuously or quasi-continuously firing thrusters, such as stationary plasma thrusters or xenon ion propulsion systems, that applies tri-axiality counter-displacements and implements optimal two-phase continuous acceleration cycles with hybrid control loops to achieve efficient ΔV performance and mitigate thruster plume impingement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ion thrusters are fired for longer duration to achieve the same ΔV, then specific impulse efficiency is improved, but electric power consumption increases and long-arc ΔV losses occur
Solution Approach 1:
The patent implements periodic thruster firings structured in two phases: a first phase firing during the first half of the orbital period and a second phase firing during the second half. This periodic action allows the thruster to accumulate ΔV efficiently over the orbital period while avoiding continuous operation, thus reducing peak power consumption while maintaining fuel efficiency.
Solution Approach 2:
The thruster operation is segmented into distinct phases corresponding to different portions of the orbital period. The first phase operates during the first half of the orbit and the second phase during the second half, with each phase targeting specific longitudinal drift corrections. This segmentation enables optimized power usage by distributing thrust events rather than requiring continuous operation.
2Measurement precision
If ion thrusters are fired frequently for small-ΔV corrections, then station keeping precision is improved, but total thruster firing duration and complexity increase
Solution Approach 1:
The control program uses periodic thruster firings synchronized with the orbital period, implementing corrections at predictable intervals rather than continuously. This reduces control complexity by establishing a regular pattern of operations while maintaining precision through targeted phase-specific maneuvers.
Solution Approach 2:
The patent maintains continuous longitudinal control by ensuring that the combined effect of the first and second phase firings provides ongoing correction throughout the orbital period. This continuous useful action achieves station keeping precision without requiring frequent discrete interventions, simplifying the control logic.
3Speed
If thruster is canted to pass through center of mass, then longitudinal drift control is improved, but radial thrust component increases affecting solar arrays
Solution Approach 1:
The patent alternates between two canting configurations in sync with the orbital period. During the first phase, the thruster is canted in one direction to counter westward drift; during the second phase, it is canted in the opposite direction to counter eastward drift. This periodic reversal optimizes longitudinal control while distributing radial thrust effects, reducing net plume impingement on solar arrays compared to a fixed canting angle.
Solution Approach 2:
The thruster canting angle is made dynamic rather than fixed, changing in coordination with the orbital position and drift direction. This dynamic adjustment allows the system to optimize longitudinal control effectiveness at different points in the orbit while minimizing harmful radial thrust components that would otherwise continuously impinge on solar arrays.
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 allows for efficient longitude/drift control with low thrust, high specific impulse ion thrusters, minimizing fuel consumption and maintaining a desired orbit locus despite orbit determination and propagation errors, while also reducing the impact of radial thrust on solar arrays.
Implementation Method 1
the satellite has a continuously or a quasi-continuously firing thruster... the thruster includes a stationary plasma thruster (SPT), or a xenon ion propulsion system (XIP)
Data Source
AI summary
A satellite longitude and drift control method is provided that includes providing a satellite that has a continuously or a quasi-continuously firing thruster, where the thruster is disposed to apply accelerations which counter a tri-axiality displacement in an orbit of the satellite, and the satellite thruster is disposed to achieve optimal ΔV performance in the presence of orbit determination and orbit propagation errors. The method further includes targeting an optimal two-phase continuous acceleration target cycle using the continuously or the quasi-continuously firing thruster, providing a closed loop and a hybrid loop implementation of the thruster firing, where the hybrid loop implementation includes an open and closed loop implementation, and where the closed loop and the hybrid loop implementations are disposed to provide quasi-continuous implementations of an optimal continuous control program.