Satellite Attitude Control via Segmented Axis Rotation
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Solution Overview
Problem
Satellites with large payloads face challenges in maximizing solar energy absorption while performing frequent and large rotations, which puts costly demands on the attitude control system due to increased moment of inertia.
Innovation Solution
A satellite design where the payload is disposed along a first axis and rotatable solar panels are along a second axis perpendicular to it, allowing for efficient orientation to face the Sun and direct sensors at terrestrial targets by rotating only about the first axis, minimizing the use of high-capacity motive elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the satellite rotates frequently and through large angles to direct sensors at terrestrial targets, then the payload data collection capability is improved, but the requirements on the attitude control system (particularly motive elements) increase significantly
Solution Approach 1:
The satellite is divided into functionally independent rotational segments: the payload array can rotate independently about the flight path axis to track terrestrial targets, while the solar panels rotate independently about the satellite body axes to track the Sun. This segmentation allows each subsystem to perform its function without requiring the entire satellite to undergo complex attitude maneuvers, thereby reducing the burden on the main attitude control system.
Solution Approach 2:
The payload array is positioned with its rotation axis aligned with the satellite's flight path axis (a dimension independent of the solar panel tracking dimensions). This allows the payload to track terrestrial targets by rotating in a different dimensional space than the solar panels, enabling simultaneous or independent operation without conflicting attitude control requirements.
2Productivity
If the satellite orientation is changed frequently for payload operations, then the sensor targeting capability is improved, but the solar energy collection efficiency deteriorates
Solution Approach 1:
The satellite's orientation control is segmented into independent rotational degrees of freedom: the payload array rotates about the flight path axis to target sensors, while the solar panels rotate about the satellite body axes to maintain Sun orientation. This allows the payload to perform targeting operations without compromising the solar panels' ability to collect energy, as each subsystem operates in its own rotational domain.
Solution Approach 2:
The system dynamically adjusts the orientation of different subsystems independently: the payload array dynamically tracks terrestrial targets by rotating about the flight path axis, while the solar panels dynamically track the Sun by rotating about the satellite body axes. This dynamic independence ensures that sensor targeting and solar energy collection can occur simultaneously or in sequence without one compromising the other.
3Adaptability or versatility
If high-capacity motive elements are used to enable frequent large rotations, then the payload deployment flexibility is improved, but the satellite cost increases
Solution Approach 1:
The rotational capability is segmented into two independent systems: a lightweight payload rotation mechanism about the flight path axis, and a separate solar panel rotation mechanism about the satellite body axes. This eliminates the need for a single high-capacity motive element that would be required to rotate the entire satellite for both functions, thereby reducing mass while maintaining full operational flexibility.
Solution Approach 2:
The payload rotation function is extracted from the main satellite attitude control system. Instead of using the satellite's primary motive elements to rotate the entire satellite for payload targeting, a dedicated lightweight rotation mechanism is provided for the payload array about the flight path axis. This extraction allows the main attitude control system to focus on solar panel tracking and orbital maintenance, reducing overall system mass.
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 design optimizes solar energy collection and sensor data acquisition without the need for high-capacity attitude control elements, reducing operational costs and maintaining efficient solar power absorption during non-payload data collection modes.
Implementation Method 1
The satellite's solar panels are also rotated about the second (y) axis at a first angle (θ) from the satellite orbital plane to orient the solar panels towards the Sun
Data Source
AI summary
A method and apparatus for maneuvering a satellite in orbit to alternately optimize the collection of solar energy and to take sensor data of terrestrial objects is disclosed The longitudinal axis of a large payload package is oriented perpendicular to the orbital plane to minimize the disturbance torque due to gravity gradient, and to allow simple rotation about the axis for attitude change between optimal Sun and optimal ground coverage.