Spacecraft Orbit Determination During Thruster Maneuvers
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Solution Overview
Problem
Accurate determination and control of spacecraft orbit, particularly for geostationary satellites, is challenging due to poor GPS satellite visibility and geometry, and is further complicated by thruster maneuvers.
Innovation Solution
A GPS-based system that includes a receiver, a filter configuration control module, and an orbit determination filter to sense thruster operations and adjust the spacecraft's position, velocity, and residue acceleration, using an orbit propagator to propagate the spacecraft's position and velocity in an Earth-centered inertial coordinate system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS satellites are used for orbit determination of GEO spacecraft, then orbit position can be determined, but GPS satellite visibility and geometry are poor at GEO orbit
Solution Approach 1:
The filter configuration control module performs preliminary detection of thruster maneuver operations before they affect orbit determination. By anticipating thruster events and pre-configuring the filter accordingly, the system prepares to handle the upcoming measurement disturbances, maintaining orbit determination precision despite poor GPS geometry
Solution Approach 2:
The orbit determination filter is made dynamic by allowing its configuration to change based on detected thruster maneuvers. The filter adapts its parameters and structure in real-time according to the operational state, switching between different filter configurations to optimize performance during both normal operation and thruster maneuver conditions
2Ease of operation
If thruster maneuvers are performed to control spacecraft orbit, then orbit control is achieved, but orbit determination accuracy deteriorates due to maneuver interference
Solution Approach 1:
The system implements feedback by continuously monitoring GPS measurements and comparing them with predicted orbit values. When thruster maneuvers are detected, the filter configuration control module adjusts the filter parameters based on this feedback, compensating for the maneuver-induced errors and maintaining orbit determination accuracy throughout the maneuver process
Solution Approach 2:
The filter configuration control module acts as an intermediary between the thruster maneuver commands and the orbit determination filter. It processes the maneuver information and translates it into appropriate filter parameter adjustments, mediating the conflict between maneuver execution and accurate orbit measurement
3Measurement precision
If filter parameters are adjusted to handle thruster maneuvers, then orbit determination during maneuvers improves, but system complexity increases
Solution Approach 1:
The filter configuration control module implements self-service by automatically detecting thruster maneuvers and autonomously adjusting filter parameters without requiring external intervention. The system monitors its own performance, detects anomalies caused by thruster operations, and self-corrects by reconfiguring the filter, thereby managing complexity internally while maintaining simple external operation
Data Source
AI summary
A system for determining and controlling an orbit of a spacecraft may include a GPS receiver mounted to the spacecraft to receive GPS information from a plurality of GPS satellites visible to the GPS receiver for determining a position of the spacecraft relative to a reference coordinate system. The system may also include a filter configuration control module to sense a thruster maneuver operation to adjust the orbit of the spacecraft. The system may also include an orbit determination filter to determine at least one of a spacecraft position, velocity, and residue acceleration based on the GPS information and information from the filter configuration control module related to the thruster maneuver operation.