Solar Array Momentum Control via Selective Cell Deactivation
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Solution Overview
Problem
Spacecraft face challenges in maintaining directional pointing due to finite momentum capacity of reaction wheels and the weight and space requirements of thrusters for momentum unloading, which limits mission life and efficiency in counteracting environmental forces like solar pressure.
Innovation Solution
The spacecraft employs a solar array momentum control system that selectively activates and deactivates solar cell sections to generate torque based on differences in solar and thermal radiation pressure, allowing for adjustable angular momentum management without the need for additional thrusters or increased mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reaction wheels are used to maintain spacecraft pointing, then directional control is achieved, but the finite momentum capacity causes saturation limiting mission life
Solution Approach 1:
The patent converts the harmful solar radiation pressure into a beneficial torque source for momentum unloading. By strategically deactivating solar cell sections, the spacecraft creates asymmetric radiation pressure that generates controlled torque to counteract momentum accumulation in reaction wheels, extending mission life without additional fuel.
Solution Approach 2:
The solar array itself serves dual functions: generating electrical power and providing momentum control through differential radiation pressure. The system uses its own structure and environmental interaction (solar pressure) to resolve the momentum saturation problem, eliminating the need for separate momentum management resources.
2Reliability
If thrusters are added for momentum unloading, then angular momentum can be removed, but significant space and weight are occupied
Solution Approach 1:
The solar array is designed to perform multiple functions simultaneously: electrical power generation and momentum control. By deactivating specific solar cell sections, the same structure that generates power also creates asymmetric radiation pressure for torque generation, eliminating the need for dedicated thruster systems.
Solution Approach 2:
The patent replaces the mechanical thruster system with a radiation pressure-based control mechanism. Instead of using propellant-driven thrusters to unload momentum, the system exploits solar radiation pressure on asymmetrically deactivated solar cells to generate the necessary torque, significantly reducing mass requirements.
3Reliability
If additional momentum unloading thrusters are installed, then momentum unloading is enabled, but the fuel amount is finite shortening mission life
Solution Approach 1:
The system converts the previously harmful or wasted solar radiation pressure into a useful resource for momentum control. By strategically deactivating solar cell sections, the spacecraft harnesses radiation pressure to generate torque for momentum unloading, replacing finite fuel-based thruster operations with an effectively unlimited solar-powered mechanism.
4Reliability
If solar cell sections are deactivated to generate torque, then momentum control is achieved, but electrical power generation is reduced
Solution Approach 1:
The system deactivates only specific portions of the solar array necessary for momentum control while keeping the majority of solar cells active for power generation. This partial deactivation approach achieves the required torque for momentum management while minimizing the impact on overall electrical power output.
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 enables efficient momentum control, reducing the reliance on thrusters and reaction wheels, conserving space and weight, and extending mission life by leveraging solar and thermal radiation pressure to maintain directional pointing and counteract environmental forces.
Implementation Method 1
Each of the solar cell sections can be configured to generate electrical power from received solar radiation
Implementation Method 2
generate a torque on the spacecraft based on a difference in at least one of solar and thermal radiation pressure between an activated portion of the array of solar cell sections and the deactivated portion
Implementation Method 3
generate a torque on the spacecraft based on a difference in at least one of solar and thermal radiation pressure between an activated portion of the array of solar cell sections and the deactivated portion
Data Source
AI summary
One embodiment of the invention includes a spacecraft. The spacecraft comprises at least one solar array panel comprising an array of solar cell sections. Each of the solar cell sections can be configured to generate electrical power from received solar radiation. The spacecraft also comprises a solar array selection controller configured to selectively deactivate a portion of the array of solar cell sections to generate a torque on the spacecraft based on a difference in at least one of solar and thermal radiation pressure between an activated portion of the array of solar cell sections and the deactivated portion of the array of solar cell sections.