Talk:Electrodynamic tether

"Closed" vs "Open" circuit
Dudes, current flow requires a closed circuit. Open systems theory has nothing to do with it. Current flows from one end of the tether, through the surrounding environment, to the other end of the tether, down through the tether back to the start point. That's a closed circuit, not an open circuit. Please don't revert unless you can explain it here. Rpresser 16:52, 11 April 2006 (UTC)


 * Sir, current flow requires a circuit. Open systems theory has everything to do with it. Current flows from one end of the tether (the circuit), through the surrounding environment (not the electronic circuit), and back to the tether. That's a open circuit, not closed circuit (just of electronic elements). J. D. Redding 17:16, 11 April 2006 (UTC)


 * Just let me state that a different phrase may be needed. Although a voltage will build up between the ends of a conducting tether, no current will flow unless the "circuit is completed" [between the environment and the tether]. I understand that many times "closed circuit" means that there is a "full path" and "open circuit" means "not a full path" ... but this is not what is meant by the text, it means that there is "interaction in the outside environment (the plasma mediums of space) the electronic circuit proper (the tether)" [aka., an open system]. J. D. Redding 17:43, 11 April 2006 (UTC)

We're getting closer to agreement; the phrase you are using ("current will not flow unless a open circuit exists") makes no sense. Closed circuit is the only term that is ever used in connection with a current flow; not just "many times" but every time. If you want to talk about the system receiving energy from the outside environment and reference open systems theory, fine, but don't use the phrase open circuit. Or find me some reference, perhaps one specifically on tethers, that uses the phrase open circuit just the way you are using it, and I'll be convinced. But with the sentence that follows the one under argument, I really don't see how anything but "closed circuit" makes sense. You're talking about an electrical circuit, and open electrical circuits are ones where the current flow is broken. Ask any electrician. 14:30, 12 April 2006 (UTC)


 * Your point is of terminology, not concepts. "Open" electrical circuits that use the environment is well know to knowledgeable electricians. 204.56.7.1 14:51, 12 April 2006 (UTC)

Seeing that the only mention of "open system" on the phantom loop page was added by Mr. Redding, my opponent in this discussion, I am still less than convinced. If you want to label this as a terminology dispute I will accept that label, but the terminology "open circuit" remains confusing, as evidenced by this argument here. See the open circuit disambiguation page, for Pete's sake. "In electronics, where there is nothing connected to a load and no current can flow."

Bert Hickman, thank you! I am content with this resolution. Mr. Redding? Rpresser 18:35, 13 April 2006 (UTC)

Thank you Heron and Bert Hickman. The article is much better now. 204.56.7.1 14:22, 14 April 2006 (UTC)

That was possibly the most civil content dispute I've ever witnessed on Wikipedia. A pat on the back for all of you. -Toptomcat 19:02, 18 February 2007 (UTC)

Voltage and current
This section really needs to be rewritten. In its previous incarnation it made references to the magnetic field rotating with the Earth, but electromagnetic theory admits of no such rotation. I've removed those references, but the result is hardly an improvement in terms of understandability.

The movement of charges in a conducting tether can be explained either as a lorentz force acting on those charges when they are moving relative to some observer in a magnetic field, or alternatively as a response to the electric field that exists as a result of a lorentz transformation from the frame of that observer to the frame of the charges. To avoid the complication of the observer also seeing an electric field, we need to make the observer stationary relative to the axis about which the currents in the Earth's core are flowing. Since that axis presumably at least roughly intersects the Earth's axis of rotation, we can conveniently make the observer stationary relative to the centre of the Earth. Such an observer sees only a magnetic field (leaving aside a residual electric field that results from separation of charges in the Earth's core as they move in the magnetic field that they are creating). The velocity used both in calculating both the lorentz force on the charges in the tether, and the lorentz transformation into the frame of the tether, is the orbital velocity relative to the stationary observer.

Now, all of that could go into the article, but it would really be obscuring the main focus of the article. The problem I'm having is how to explain the charge displacement, and possible resulting current, in a way that is physically valid and doesn't lead to flawed notions about eletromagnetism, but doesn't drown the reader in a morass of detail that they're probably not interested in.

Sylvia 22:22, 6 March 2007 (UTC)

The following relates this to the Space elevator and perhaps can be a new article and/or incorporated somewhere: The Wikipedia article is about conductive tethers in low earth orbit with a speed of about 17,000 miles per hour with respect to Earth's magnetic field. The 91,000 kilometer space elevator will move much slower = lower voltage, current and electrodynamic thrust, and may be a non-conductor. An electrical conducting space elevator will produce additional vibrations = transients as a result of electric current flow. Adjusting the current flow will suppress transients of some kinds, but a learning period will be necessary as the tether is built, as our computer models will likely have considerable error. Moving the anchor ship also produces transients, but sufficiently accurate timing to cancel transients (with transients) may be occasionally unsuccessful, with tangling, excessive tension, slack ribbon or rubbing the result. Correcting 99% of the bad transients may not be sufficient. Weeks is possible, but my guess is transients will be close to negligible one week after they are created, unless they are deliberately prolonged. My guess is tide induced transients will be tiny even if the space elevator is 200,000 kilometers long, but tides and transients will require careful monitoring of the ribbon tension over the entire length. Ccpoodle (talk) 03:29, 6 April 2010 (UTC)

worse than useless
Unintelligible. Scrap the whole thing and start over. So disgusted with this so-called encyclopedia.


 * In contrast I found this to be one of the best articles written in all of Wikipedia. It goes from general principles well understand by anyone with a reasonable k-12 education and then get's into details rarely found on Wikipedia. I loved it. Good job authors! War (talk) 17:31, 10 December 2016 (UTC)

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Assuming a standard east to west orbit around Earth?
Under the 'Electrodynamic tether fundamentals' section : '(Assuming a standard east to west orbit around Earth)' - Maybe I'm missing something here, but isn't a standard orbit west to east? — Preceding unsigned comment added by Sam Pender (talk • contribs) 05:34, 15 July 2018 (UTC)