Absolute Targeting via Star Sensor and Laser Ranging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current star sensors in space missions cannot achieve the required absolute pointing accuracy of a tenth of a second of arc due to mechanical and thermoelastic biases, making precise calibration difficult and costly, and adding weight to satellites.
Innovation Solution
Coupling a star sensor with an optical metrological sensor to accurately determine relative positions, allowing the star sensor to roughly point towards a known bright star, and the optical sensor to provide optimized absolute accuracy within its measurement tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional star sensors are used for absolute pointing, then the system can determine absolute direction using known star catalogues, but the pointing accuracy is limited to several seconds of arc due to mechanical and thermoelastic biases
Solution Approach 1:
The patent introduces a laser range finder as an intermediary device between the star sensor and the target. The laser range finder provides precise relative distance measurements that compensate for the inaccuracies in star sensor absolute pointing. By combining the absolute directional information from the star sensor with the precise relative distance from the laser range finder, the system achieves high-precision target location without requiring perfect calibration of the star sensor's mechanical and thermal biases
Solution Approach 2:
The patent changes the measurement parameters by combining absolute angular measurements from the star sensor with relative distance measurements from the laser range finder. This parameter transformation allows the system to achieve sub-second of arc accuracy by computing target position in three-dimensional space using the formula: target position = star direction vector × stellar distance, where the stellar distance is precisely measured by the laser range finder
2Measurement precision
If new high-accuracy star sensors are developed to achieve less than a second of arc accuracy, then the absolute pointing precision improves, but the satellite weight and cost increase significantly
Solution Approach 1:
The patent merges two existing instruments - the star sensor and the laser range finder - into a hybrid absolute target system. The star sensor provides absolute directional information while the laser range finder provides precise distance measurement. By combining these two functions, the system achieves high-precision pointing (less than a second of arc) without the need for a completely new high-accuracy star sensor, thereby avoiding additional weight and cost
Solution Approach 2:
The patent makes existing instruments serve multiple functions. The star sensor, originally designed for absolute pointing, is combined with the laser range finder's distance measurement capability to create a multi-functional system that achieves both absolute orientation and precise ranging. This multi-functionality allows the system to achieve high-precision targeting using existing hardware without additional weight
3Measurement precision
If new high-accuracy star sensors are developed to achieve less than a second of arc accuracy, then the absolute pointing precision improves, but the development cost increases significantly
Solution Approach 1:
The patent merges two existing instruments - the star sensor and the laser range finder - into a hybrid absolute target system. The star sensor provides absolute directional information while the laser range finder provides precise distance measurement. By combining these two functions, the system achieves high-precision pointing (less than a second of arc) without the need for a completely new high-accuracy star sensor, thereby avoiding additional weight and cost
Solution Approach 2:
The patent makes the existing laser range finder serve an additional function - providing distance information for absolute targeting. By utilizing the self-service capability of the laser range finder for both formation flight ranging and absolute target positioning, the system achieves high-precision pointing without additional development cost for new sensors
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
Achieves absolute pointing accuracy of less than 0.1 seconds of arc without adding weight or cost, by leveraging existing sensors on satellites and allowing ground calibration of the optical metrological sensor.
Implementation Method 1
the optical metrological sensor then accurately determining the direction of said known bright star in its own frame of reference
Data Source
AI summary
The present invention relates to an absolute target system intended to be incorporated in observation satellites. To establish an absolute target system provided with maximum accuracy, the present invention proposes coupling a star sensor (4) to an optical metrological system (5N, 5R). Since these two items of equipment are normally already on board the satellites, in particular for formation flight missions, this solution adds no extra weight or cost.