Floating Conductive Tethers for Propellantless Spacecraft Orbit Control
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Solution Overview
Problem
Current propulsion systems for spacecraft, such as chemical and electric rockets, require fuel and energy, increasing launch costs and limiting satellite lifespan, while electrodynamic tethers with hollow cathodes face inefficiency and gas storage issues, and floating tethers lack efficient electron emission mechanisms.
Innovation Solution
A floating tether design where the tethers themselves trap and emit electrons, with an electrical power source connected to two sets of conductive tethers, utilizing photoelectric emission and high electron-emissivity materials like alkaline metals or compounds to facilitate efficient electron exchange with ambient plasma, allowing for propellantless propulsion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If chemical or electric rockets are used for spacecraft propulsion, then thrust and orbital manoeuvres can be achieved, but fuel mass increases launch costs and limits satellite lifespan
Solution Approach 1:
The invention extracts the propellant requirement entirely from the propulsion system by using the Earth's magnetic field and ionospheric plasma as the reaction medium. The tether collects electrons from the ionosphere and uses the Lorentz force from the magnetic field to generate thrust without expelling any propellant mass, thereby eliminating the weight penalty of fuel storage.
Solution Approach 2:
The invention replaces the mechanical chemical combustion process or electric plasma acceleration with an electromagnetic interaction system. Instead of burning fuel to generate thrust mechanically, the system uses electromagnetic induction to generate current in the tether, which interacts with the magnetic field to produce Lorentz force, substituting chemical/electric propulsion with direct electromagnetic propulsion.
2Reliability
If hollow cathodes are used on electrodynamic tethers to emit electrons, then current flow can be maintained, but cathode efficiency degrades over time and requires inert gas storage
Solution Approach 1:
The invention makes the tether self-sufficient by eliminating the hollow cathode and its inert gas storage system. The tether naturally collects electrons from the ionospheric plasma through its motion across magnetic field lines, generating the necessary current without requiring active electron emission devices or propellant storage, thereby simplifying the system and improving reliability.
Solution Approach 2:
The invention removes the hollow cathode assembly and inert gas storage system from the tether design. By extracting this complex subsystem, the patent relies on the natural interaction between the moving tether and ionospheric plasma to provide the necessary electrons for current flow, eliminating the reliability issues and complexity associated with cathode maintenance.
3Force
If traditional electrodynamic tethers are used, then propulsion can be achieved, but the system requires complex cathode control mechanisms and gas management
Solution Approach 1:
The tether system operates autonomously by naturally collecting electrons from the ionosphere through its orbital motion. The system requires no active control of electron emission, no gas flow management, and no cathode maintenance, making the operation extremely simple while maintaining the Lorentz force propulsion mechanism.
4Weight of moving object
If propellantless propulsion is implemented using floating tethers, then fuel mass is eliminated, but efficient electron emission mechanisms are lacking
Solution Approach 1:
The invention replaces the need for active electron emission mechanisms with a passive electromagnetic induction process. As the tether moves through the magnetic field, an electromotive force is induced that naturally drives electron collection from the ionosphere, eliminating the need for thermionic or photoelectric emission systems while maintaining propellantless operation.
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 provides a robust, propellantless propulsion system that maintains efficiency even if a tether is cut, with controlled current direction and Lorentz force, enabling altitude adjustments or orbit maintenance without fuel or expellant, and can optimize electron emission through thermionic or photoelectric mechanisms.
Implementation Method 1
the Lorentz force exerted by the magnetic field on the current that flows along the tether
Implementation Method 2
the electromotive force gives control over the current and therefore also over the Lorentz force
Implementation Method 3
the tether acts like a Langmuir probe that naturally captures electrons from ambient plasma
Implementation Method 4
The cathode generates a low-impedance path for the electrons, which are returned to the plasma, giving rise to a stationary current along the tether
Implementation Method 5
utilizing photoelectric emission and high electron-emissivity materials like alkaline metals or compounds to facilitate efficient electron exchange with ambient plasma
Implementation Method 6
can optimize electron emission through thermionic or photoelectric mechanisms
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a system for in-orbit propulsion via floating conductive tethers loaded in a spacecraft (1), comprising two sets of electro-dynamic conductive tethers (2, 3), respectively connected to each of the two poles (4, 5) of a source (6) for generating electrical power, and wherein each set is formed by at least one conductive tether. In the presence of plasma and a magnetic field, such as in the ionosphere of the earth, an electrical current flows naturally along the conductive tethers. A Lorentz force is generated over the tethers via the interaction of the magnetic field with said current. Said force can be used to control the orbit of the spacecraft (1), varying the same in terms of direction and magnitude by means of the electrical power-generating source (6), thereby permitting the modification of the intensity and direction of the current along the tethers.