Space tethers are an intriguing propulsion or source of 'free energy' to power satellites, space stations, spacecraft or even perhaps spaceships.
It seems that different space electrical tether systems use a combination of gravity forces, electromagnetic forces, electrons, ionosphere and their potential differences around planet Earth.
One of the first space tether experiments (Tethered Satellite System or TSS) caused an event that destroyed itself, due to a surprising surge or amount of electrical energy created and flowing through the tether. This was certainly used back in the early days of the modern EU theory as Electric Universe evidence.
Drake Dorosh in the discussion/ideas area asked about Electric Universe spacecraft. Would electrodynamic tethers or other types of space tether propulsion systems be one way to help power an Electromagnetic spaceship at the start but would it work in deeper space?
Would you need to find and use Birkeland currents to obtain the required mixture of plasma, electromagnetic energy, gradients? Are there any other space plasma phenomena that you could use for a spaceship tether?
Space Tether Experiments
As the broken end whipped away from the shuttle, the plasma established electric contact with the ionosphere directly
The space tether experiment, a joint venture of the US and Italy, called for a scientific payload--a large, spherical satellite--to be deployed from the US space shuttle at the end of a conducting cable (tether) 20 km (12.5 miles) long. The idea was to let the shuttle drag the tether across the Earth's magnetic field, producing one part of a dynamo circuit. The return current, from the shuttle to the payload, would flow in the Earth's ionosphere, which also conducted electricity, even though not as well as the wire.
... The deployment was almost complete when the unexpected happened: the tether suddenly broke and its end whipped away into space in great wavy wiggles ... The nature of the break suggested it was not caused by excessive tension, but rather that an electric current had melted the tether
... The instruments aboard the tether satelite showed that this plasma diverted through the pinhole about 1 ampere, a current comparable to that of a 100-watt bulb (but at 3500 volts!), to the metal of the shuttle and from there to the ionospheric return circuit. That current was enough to melt the cable ... As the broken end whipped away from the shuttle, the plasma established electric contact with the ionosphere directly.
The Space Tether Experiment | NASA
The tether generated currents were higher than expected
Johnson leads a team of engineers and scientists at NASA's Marshall Space Flight Center developing ProSEDS, a tether that will "plug in" to the same physics principle that powers electric motors. Forces can be generated by sending a current through a wire loop - i.e. an electrical circuit - while it lies in a magnetic field. In space, one part of the electrical circuit is a long tether attached to an orbiting spacecraft. The return path of the circuit is supplied by the electrically charged gas in the ionosphere. The magnetic field is supplied by Earth. When properly controlled, the forces generated by this "electrodynamic" tether can be used to pull or push a spacecraft to act as a brake or a booster.
The ProSEDS concept builds on results from the second flight of the Tethered Satellite System (TSS-1R) in 1996 which gave scientists a surprise. The system was designed so that the satellite would be biased to a high positive voltage and collect electrons from the ionosphere.
"The theoretical models we had for current collection from the ionosphere before the mission were not accurate," said Dr. Nobie Stone, TSS project scientist at NASA/Marshall. "The tether-generated currents were higher than we had expected, and this is good news for future applications."
Spacecraft may fly on "empty" using propulsive tether concept | NASA
Two different shuttle missions — Atlantis' STS-46 in 1992 and Columbia's STS-75 in 1996 — took a crack at deploying a satellite, then dragging it through space connected by a 13-mile-long (21-kilometer) conducting tether.
The experiment, called the Tethered Satellite System (TSS), was a joint effort between NASA and the Italian space agency. The idea was to show that tethered satellites could generate electric current as they cruised through Earth's magnetic field.
During STS-46, the tether unspooled just 840 feet (256 meters) from Atlantis before the reel jammed. Four years later, 12.2 miles (19.7 km) of cable were released before the 0.1-inch (0.25 centimeter) tether snapped, sending the probe shooting away into a higher orbit.
Though neither attempt was 100 percent successful, the TSS belongs on this list for its scale and ambition alone. And the 1996 experiment did return some interesting results. Before the tether snapped, the TSS had been generating 3,500 volts and up to 0.5 amps of current, according to NASA officials.
Trying out a 13-mile space tether - 6 Coolest Space Shuttle Science Experiments | Space.com
Unlike chemical and rocket systems, which must expell a propellant to create thrust, an electrodynamic tether generates thrust through Lorentz-force interactions with a planetary magnetic field. By using the space environment to create thrust, electrodynamic tether systems can dramatically reduce the cost of many space missions by eliminating the need to launch large quantities of propellant into orbit.
An electrodynamic tether is essentially a long conducting wire extended from a spacecraft. The gravity gradient field (also known as the "tidal force") pulls the tether taut and tends to orient the tether along the vertical direction. As the tether orbits around the Earth, it crosses the Earth's magnetic field lines at orbital velocity (7-8 km/s!). The motion of the conductor across the magnetic field induces a voltage along the length of the tether. This voltage, which is called the "motional EMF", can be up to several hundred volts per kilometer.
In an "electrodynamic tether drag" system, such as our Terminator Tape and Terminator Tether products, the tether can be used to reduce the orbit of the spacecraft to which it is attached. If the system has a means for collecting electrons from the conducting ionospheric plasma at one end of the tether and expelling them back into the plasma at the other end of the tether, the motional EMF voltage will drive a current along the tether. This current will, in turn, interact with the Earth's magnetic field to cause a Lorentz JXB force which will oppose the motion of the tether and whatever it is attached to. This "electrodynamic drag force" will decrease the orbit of the tether and its host spacecraft. Essentially, the tether converts the orbital energy of the host spacecraft into electrical power, which is dissipated as ohmic heating in the tether.
Electrodynamic Tethers | Tethers Unlimited
Electrodynamic tethers are typically between five and 20 kilometers long. As the long wire moves through Earth's magnetic field, the changing magnetic field in the vicinity of the wire induces a current that flows up the tether. If a power supply is added to the tether system and used to drive current in the other direction, an electrodynamic tether can "push" against the Earth's magnetic field to raise the spacecraft's orbit. The major advantage of this technique compared to other space propulsion systems is that it doesn't require any propellant. The Earth and the red curves denote planetary magnetic field lines. Currents are induced in conducting wires as they orbit through the magnetic field.
A Little Physics And A Lot of String | NASA
Propellant-free propulsion technology has taken a critical step toward reality, completing a series of systems tests at NASA's Marshall Space Flight Center in Huntsville, Ala. The Propulsive Small Expendable Deployer system - called ProSEDS - is a tether-based propulsion experiment that draws power from the space environment around Earth, allowing the transfer of energy from the Earth to the spacecraft.
... The initial flight of ProSEDS, scheduled for early summer, will mark the first time a tether system is used for propulsion. To be launched from Kennedy Space Center, Fla., ProSEDS will fly aboard an Air Force Delta II rocket and demonstrate an electrodynamic tether's ability to generate significant thrust.
... During the tests, all subsystems functioned as designed, including the hollow cathode plasma contactor, a critical component that enables the tether system to complete its electrical circuit.
During the flight, the process of collecting energy will begin when the electromagnetic portion of the tether collects electrical current along the tether's length as it moves through the Earth's magnetic field. To keep the current flowing, the plasma contactor reconnects the electrons with the invisible, electrically charged plasma that surrounds the Earth, emitting the electrons back into space so it can complete its circuit.
NASA prepares to launch space tether experiment | Space Flight Now
The ProSEDS system requirements drove the design of the tether to have three different sections of tether each serving a specialized purpose. The tether is a total of 15 kilometers long: 10 kilometers of a non-conductive Dyneema lead tether; 5 km of CCOR conductive coated wire; and 220 meters of insulated wire with a protective Kevlar overbraid.
Development of the flight tether for ProSEDS
When analysis suggested that several ProSEDS key performance parameters could not be met, NASA decided not to fly the mission. It was expected that particle impacts on the tether would compromise the insulating properties of portion of the tether before mission science goals could be met.
ProSEDS - Propulsive Small Expendable Deployer System | Utah State University