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### Do orbiting wires generate?

Posted: Thu Aug 11, 2005 11:19 am
Hi.
Does the wiring inside satellites or the shuttle generate electricity (or unwanted electrical noise) by crossing the earth magnetic field ?
Miguel

### Re: Do orbiting wires generate?

Posted: Thu Aug 11, 2005 1:21 pm
<p>[ August 11, 2005: Message edited by: dacflyer ]</p>

### Re: Do orbiting wires generate?

Posted: Thu Aug 11, 2005 1:24 pm
i bet they could answer that.<p>
Hey, did any of you all know that NASA astronaughts wear diapers at least 3 different times during a mission??
1.during launch , they can be waiting hrs waiting for take off.
2.during space walks,,many hrs of work.cannot just come back in for a potty break
3 during re-entry , Hmmmm no explanitatin there..have to figgure in that pucker factor..lol<p>thank goodness for DEPENDS {:>D

### Re: Do orbiting wires generate?

Posted: Thu Aug 11, 2005 1:55 pm
I would bet not when they are in orbit since they are not crossing any lines of force. Maybe between ascent and descent. However, I bet the amount is very small.

### Re: Do orbiting wires generate?

Posted: Thu Aug 11, 2005 3:10 pm
Shouldn't be too difficult to work out (Unless of course it was me trying it) - The Earth magnetic field strength varies inversely as the squzre of the distance from the centre of the Earth so the filed strength (Tho extremely small) is known - Voltage generated is the Sine of direction to field normal multiplied by B.l.v wqhere B is the field strength in Webers.metre squared, l is length of conductor in metres and v is velocity of conductor/field relative movement in metres/sec

### Re: Do orbiting wires generate?

Posted: Thu Aug 11, 2005 4:10 pm
I think the shell of the craft would shield any interior wiring from the effect. And, in order for the shell to develop a voltage, there would have to be a potential difference across it- not likely, since it's a one turn coil.
However, if they dragged a substantial length of wire behind the craft........perhaps a few miles- I could see some generation there!

### Re: Do orbiting wires generate?

Posted: Thu Aug 11, 2005 4:12 pm
will
No doubt about a weak feild at that point in space, but with the orbiters tremendous velocity, would that make up for a weak feild?

### Re: Do orbiting wires generate?

Posted: Thu Aug 11, 2005 5:57 pm
The velocity of the orbiter even with a wire trailing behind it and the orbiter going nose first would not generate anything significant since the motion of a generating conductor has to be such its' direction of travel has to be perpendicular both to the length of the conductor and the direction of the magnetic field i.e if we assume that the Earth magnetic field direction is North/South i.e. the field lines exit one of the poles, travel perpendicular to the equator and return to the other pole. That means that any long conductor would need to have its' length in the plane of, or in a plane parallel to, the equator and be travelling in a direction perpendicular to its' length (The length of the conductor) There is no doubt that such an arrangement would generate some voltage (Didn't NAS already have an experiment with a long conductor hanging in space ?) Even so - how would you measure the volts - If you had to have instrument/meter leads long enough to take a measurement from both ends of the travelling conductor then wouldn't the leads have the same voltage generated, but equal and opposite in the loop ?

### Re: Do orbiting wires generate?

Posted: Thu Aug 11, 2005 6:45 pm
Some years ago NASA did an experiment where they slowly SPUN a long conductor loop behind the shuttle, thus negating the nifty trig/magnetic math formulas posted peviously. It oh-so-briefly generated a rather large amount of current, dissipated through a dummy load, before the cable broke.<p>I'm still looking up details; I'll post'em when I find 'em.<p>As for wires INSIDE, proper shielding is a basic consideration for all cabling.

### Re: Do orbiting wires generate?

Posted: Thu Aug 11, 2005 9:27 pm
The answer is yes. <p>Huge amounts of tap-able power was sought by NASA for this very reason but what they didn’t figure in the equation was the weight of their experiment. <p>They trailed a long wire beind the space shuttle and produced gobs of power, but the wire length was too much and it snapped under its own weight. <p>I believe it was several miles in length and they figured ZERO grav? <p>All the wiring in the shuttle is co-ax shielded to stop stray charges biulding up in the circuitry, between potentials, and upon landing the orbiter is discharged to ground safely to stop from killing the ground crew and to save all the equipment from a high potential difference between the charge building up in space, and the charge at rest on the ground. <p>All the time the shuttle is in space, the entire body including its wiring is being charged by the rotation and magnetic fields of the earth as well as the fact that the space shuttle is one large conductor.

### Re: Do orbiting wires generate?

Posted: Thu Aug 11, 2005 9:40 pm
Hi.
I don't think the aluminium shell bodies nor copper shielding of wires block the magnetosphere at all.
In fact, very sophisticated alloys as mu-metal partially achieve it.
And the magnetosphere is not much weaker at the orbiting altitudes, and with the brutal speeds, something undesirable has to happen. Who knows what NASA does to counteract the effects...<p>My search shows only a couple of perhaps relevant results, and of course, my §ƒ¶‡ compfuser choked on both, unable to open:<p>http://www.scirus.com/srsapp/search?q=e ... +generatio n+orbit+wiring+crossing+magnetic+field&ds=jnl&ds=web&g=s&t=all<p>Wire loops EXTERNAL to orbiters failed mechanically to prove generation, and I think trailing single wire tether experiments were for other purpose -as far as I know-:
http://www-istp.gsfc.nasa.gov/Education/wtether.html<p>Miguel <p>[ August 11, 2005: Message edited by: Externet ]</p>

### Re: Do orbiting wires generate?

Posted: Thu Aug 11, 2005 10:28 pm
I don't think any of the conductors in the shuttle are long enough to pick up any substantial current.<p>But the tether experiment was indeed conducted for the purpose of generating current, and it succeeded better than they expected.<p>The reason the wire parted was not from weight. When the cable snapped, they examined the remains and found it had burned in half where it arced through the insulation to the body of the shuttle. Their engineering oversight was not in the mass of the cable, it was that they grossly underestimated just how much electricity it could generate.

### Re: Do orbiting wires generate?

Posted: Fri Aug 12, 2005 5:24 pm
The previous study by NASA that was mentioned I believe was the Gemini project. But there is actually significant interest in it now. Its actually the topic of my graduate research. There was a decent article in Popular Science or Popular Mechanics a few months ago. A lot of info can be found at NASA's website by searching for tethered satellites (or google it).
I think the best potential for the technology is realized by asking the question "How can you accelerate an object in space without expending fuel?" A force directed either towards or away from Earth is created as shown from right hand rules. If the current generated is used to charge batteries in the satellite, the force can be used to bring decomissioned satellites out of orbit. If a current is forced through the tether in the opposite direction the force can be used to keep satellites in space positioned at a specific altitude (They are considering this for the ISS). I might have those effects backwards.

### Re: Do orbiting wires generate?

Posted: Sun Aug 14, 2005 6:26 pm
Whenever a current is generated in a conductor there is a force generated as well. Any force applied to an orbiting spacecraft will effect it's orbit. It's probably a good thing that the conductor loop broke because it would have brought the craft out of orbit in a short time. Again there is no free power.

### Re: Do orbiting wires generate?

Posted: Mon Aug 15, 2005 6:42 am
Although a current might be generated, I'd think that the effect would be minimal, for if all circuits are closed loops, the current generated in one side of the loop would be pretty much cancelled by the current induced in the other side of the loop. All of this would depend upon orientation of the ciruits with respect to the various fields, of course, but for more circuits, I'd think that the problem would be minimal.<p>It is this characteristic that makes an EMP so devastating to spacecraft. Certainly in case of another global war, an EMP here an there would be critical pre-emptive moves.<p>But let's not have any more of those global war things, OK?<p>Dean