Gravity Gradient Aerobraking Sail for Satellite Deorbiting
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Solution Overview
Problem
Current satellite deorbiting technologies, particularly aerobraking systems, face challenges in maintaining stability and efficiency due to solar activity cycles, leading to a wide variation in deorbiting times, which complicates compliance with regulations requiring satellites to be deorbited within 25 years without excessive mass or hydrazine usage.
Innovation Solution
A satellite deorbiting device combining an aerobraking surface with a gravity gradient attitude control system, featuring a mast with a mass at its end to stabilize the sail perpendicular to the satellite's trajectory, optimizing aerobraking efficacy and minimizing mass while reducing the impact of solar activity on deorbiting time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an aerobraking structure is used for satellite deorbiting, then the deorbiting capability is provided, but the satellite stability deteriorates due to solar activity cycles causing wide variation in deorbiting times
Solution Approach 1:
The patent changes the physical state and parameters of the aerobraking surface by deploying it from a compact stowed configuration to an extended deployed configuration. This parameter change increases the surface area exposed to atmospheric drag, providing reliable deorbiting capability. The surface transitions from a low-drag stowed state to a high-drag deployed state, allowing control over the deorbiting process despite solar activity variations.
Solution Approach 2:
The patent employs a deployable aerobraking surface that can transition between stowed and deployed states dynamically. This dynamic capability allows the system to adapt to varying solar activity conditions by adjusting the effective drag area, thereby maintaining stable and predictable deorbiting times despite external environmental variations.
2Stability of the object's composition
If the aerobraking structure is designed to operate with incorrect satellite positioning, then stability is maintained, but the aerobraking efficacy decreases leading to excessive mass
Solution Approach 1:
The patent employs an asymmetric deployment strategy where the aerobraking surface is deployed preferentially on the side of the satellite opposite to the direction of motion. This asymmetric configuration creates a restoring moment that naturally orients the satellite correctly, maximizing aerobraking efficacy while maintaining stability without requiring symmetric deployment on all sides.
Solution Approach 2:
The patent converts the potentially harmful effect of incorrect satellite orientation into a beneficial self-correcting mechanism. The asymmetric aerobraking force generated by deploying the surface on one side creates a torque that naturally reorients the satellite to the correct attitude, turning what would be a performance-degrading condition into a stabilizing feature.
3Reliability
If a dedicated deorbiting system of high mass is carried on board, then deorbiting requirement is met, but the satellite mass increases
Solution Approach 1:
The patent uses a thin-film aerobraking surface that provides significant drag force despite having minimal mass. This flexible thin-film structure expands to create a large surface area for atmospheric interaction, enabling effective deorbiting while adding only a small fraction of the satellite's total mass, unlike traditional heavy deorbiting systems.
Solution Approach 2:
The patent replaces traditional mechanical deorbiting systems (such as heavy retro-rockets or ballast drops) with an aerodynamic braking mechanism. This substitution uses the natural atmospheric drag force acting on a deployed surface, eliminating the need for high-mass dedicated deorbiting hardware while meeting the same functional requirement.
4Reliability
If hydrazine is used to move satellite into deorbiting position, then deorbiting capability is achieved, but hydrazine consumption increases by approximately 30%
Solution Approach 1:
The patent employs a passive aerobraking mechanism that utilizes the natural atmospheric drag force to slow and deorbit the satellite without requiring active propulsion. The deployed surface automatically interacts with the residual atmosphere, eliminating the need for hydrazine consumption and providing a self-service deorbiting solution.
Solution Approach 2:
The patent substitutes chemical propulsion (hydrazine thrusters) with an aerodynamic braking system. This replacement eliminates the need for consumable propellant by using the physical interaction between the deployed surface and atmospheric molecules to provide the necessary drag force for deorbiting.
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
The solution ensures controlled and efficient deorbiting by maintaining the aerobraking surface perpendicular to the satellite's trajectory, reducing the spread of deorbiting times and minimizing mass, thus enhancing the efficacy/mass ratio and improving deorbiting predictability regardless of solar cycles.
Implementation Method 1
aerobraking surfaces, i.e. surfaces that use the residual atmosphere present in low Earth orbit as an aerodynamic brake to brake and to slow an object, and thus in the end to reduce the altitude of its orbit
Implementation Method 2
a gravity gradient device, the gravity gradient device including at least one mast carrying the aerobraking surface and a first end of which is secured to the satellite and the second end of which is provided with a mass, such that said mast orients itself in a direction opposite the direction of the planet around which the satellite orbits
Data Source
AI summary
A satellite deorbiting device including an aerobraking surface including a satellite attitude control device with gravity gradient, the device with gravity gradient including at least one mast carrying the aerobraking surface, a first end of which is secured to the satellite and the second end of which is provided with a mass, such that the mast is oriented in a direction opposing that of the planet around which the satellite orbits.