Magnetic Eddy-Current Brake for Tumbling Spacecraft Capture
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Solution Overview
Problem
Decommissioned spacecraft with high angular velocity pose a challenge for capture and deorbiting due to rotational speed limitations, which can complicate capture and subsequent operations, and existing control techniques are inefficient in managing such velocities.
Innovation Solution
An angular velocity control device comprising a stator and rotor, where the rotor is magnetized to induce braking eddy currents in the stator, utilizing Earth's magnetic field for alignment and dissipation of rotational kinetic energy, and includes lifting magnets for magnetic levitation and ground testing simulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a decommissioned satellite has high angular velocity, then it can remain in orbit longer, but capture operations become more difficult and require more propellant
Solution Approach 1:
The magnetic braking system is activated before capture operations to reduce the satellite's angular velocity. The rotor with magnets interacts with the conductive stator to generate eddy currents that create opposing magnetic fields, gradually slowing the rotation. This preliminary action makes the subsequent capture operation feasible by reducing the relative velocity between the satellite and capturing spacecraft.
Solution Approach 2:
The patent replaces active mechanical propulsion systems with a passive magnetic braking system. Instead of using engines or thrusters to slow the satellite, the invention uses magnetic fields generated by the rotor magnets interacting with the conductive stator to create electromagnetic damping. This substitution reduces the need for propellant and complex mechanical control systems during the deorbit phase.
2Ease of operation
If magnetic braking systems are used to reduce angular velocity, then capture becomes feasible, but the system complexity increases
Solution Approach 1:
The magnetic braking system is designed to be self-actuating. The rotor contains permanent magnets that automatically interact with the conductive stator to generate braking forces without requiring external control signals or power sources. The system self-regulates the braking intensity based on the relative motion between the rotor and stator, eliminating the need for complex control electronics or active management.
Solution Approach 2:
The patent extracts the braking function from the main satellite structure and places it in a separate, dedicated magnetic braking device. This extraction allows the braking system to be optimized independently and simplifies the overall control architecture by isolating the complex magnetic interaction mechanics from the satellite's primary mission systems.
3Force
If ferromagnetic materials are used in the magnetic braking system, then magnetic coupling is enhanced, but the system cannot be properly tested on ground under Earth's gravity
Solution Approach 1:
The patent applies non-ferromagnetic materials specifically in the regions where ground testing is required, while maintaining ferromagnetic or magnetized components in the rotor where magnetic coupling is needed during orbital operation. This localized differentiation allows the system to achieve strong magnetic coupling in orbit while enabling ground-based testing without the interference of ferromagnetic materials responding to Earth's gravitational field.
Solution Approach 2:
Instead of using ferromagnetic materials that would be attracted to Earth's gravity during ground testing, the patent inverts the approach by using non-ferromagnetic conductive materials for the stator and permanent magnets for the rotor. This inversion allows the magnetic braking effect to occur during orbital operation while eliminating the gravitational interference during ground testing, enabling proper validation of the braking mechanism.
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
Facilitates the reduction of angular velocity before capture, simplifies the capture process, and allows ground testing of the device under weightless conditions, ensuring efficient deorbiting of decommissioned spacecraft.
Implementation Method 1
The rotor comprises a magnetized system configured to induce braking eddy currents in the stator, counteracting the relative motion of the rotor with respect to the stator
Implementation Method 2
The rotor comprises a magnetized system configured to induce braking eddy currents in the stator
Implementation Method 3
creating a magnetic moment in the Earth's magnetic field
Implementation Method 4
The rotor comprises a magnetized system configured to induce braking eddy currents in the stator
Implementation Method 5
The rotor further comprises one (or more) lifting magnet(s) designed to cooperate with a magnetic field generated by a source external to the device to induce magnetic lift of the rotor relative to the stator
Data Source
Figure 1~2
Figure 3a~4
Figure 5~7
AI summary
The invention relates to a device (1) for controlling the angular velocity of an out-of-service spacecraft, comprising: - a stator (3) and a rotor (4) movable about an axis (A21) of rotation with respect to the stator, the stator (3) comprising an electrically conductive and non-ferromagnetic body (6) while the rotor (4) comprises a magnetized system (7) configured to induce, in the stator (3), eddy currents for braking a relative movement of the rotor (4) with respect to the stator (3); - a magnetic-suspension magnet (11) intended to cooperate with a magnetic field generated by an external source in order to suspend the rotor (4) magnetically with respect to the stator (3). The device (1) consists of one or more non-ferromagnetic materials in a zone (11ZI) of influence of the magnetic field generated by the magnetic-suspension magnet.