Sattelite Power Idea...

[sao123]

So... the earth has a fully surrounding magnetic field.
Electricity is created when a wire moves through a magnet field....

could we construct a sattelite which would power itself if placed in the proper orbit, using this principle?
discuss.

 

[Matthias99]

Originally posted by: sao123
So... the earth has a fully surrounding magnetic field.
Electricity is created when a wire moves through a magnet field....

could we construct a sattelite which would power itself if placed in the proper orbit, using this principle?
discuss.

Someone else suggested this a while back in this very forum.

You'd bleed gravitational/kinetic energy off the satellite over time, gradually reducing its speed (and eventually causing it to fall out of orbit). But it might work until then.

You can't get something for nothing.

 

[sao123]

since most sattelites only have a useful life of about 10 years (or so) how long could this be maintained with periodic chemical propulsion orbit boosts?

Are we talking weeks/months or years/decades?

 

[Gibsons]

Originally posted by: sao123
since most sattelites only have a useful life of about 10 years (or so) how long could this be maintained with periodic chemical propulsion orbit boosts?

Are we talking weeks/months or years/decades?

if you're carrying all this rocket fuel up, why not use it to create your electricity directly (fuel cell), instead converting it to kinetic energy and then to electricity? Don't have to worry about the sattelite changing its orbit constantly and I'd guess it's much more efficient.

 

[sao123]

Originally posted by: Matthias99

Originally posted by: sao123
So... the earth has a fully surrounding magnetic field.
Electricity is created when a wire moves through a magnet field....

could we construct a sattelite which would power itself if placed in the proper orbit, using this principle?
discuss.

Someone else suggested this a while back in this very forum.

You'd bleed gravitational/kinetic energy off the satellite over time, gradually reducing its speed (and eventually causing it to fall out of orbit). But it might work until then.

You can't get something for nothing.

yes...BUT...
doesnt this happen anyways now? Sattelites do interact with the magnetic field and produce some current value...we just arent using it. No matter what, they eventually slow down and orbit decay.

if you're carrying all this rocket fuel up, why not use it to create your electricity directly (fuel cell), instead converting it to kinetic energy and then to electricity? Don't have to worry about the sattelite changing its orbit constantly and I'd guess it's much more efficient.

Potential for cheaper design, construction, & deployment.
A monthly 3-10 second burn, does not consume that much fuel.
The difference is fuel cells are large and heavy, you can accomplish this without carrying as much equipment with you.

 

[Steg55]

No it wouldnt work, we covered this in a physics lecture a while back.

I can't find me notes on it - sod.

Anyway - to break the flux lines with the wire you would have to dangle it off the satalite towards earth. Also, to produce the voltage needed to power the Space Shuttle, 110v, the wire would need to be 11km long if I remember my maths correctly and THEN, once you have managed all that, you have this long wire connected at one end to the satalite with a potential difference across it. Now, how do you complete the circuit and allow a current to flow? If you looped the wire back again it would be inducing a current flowing the other way giving a net result of 0. It wouldnt work.

Steg

 

[Matthias99]

here's the earlier thread that this came up in

It's discussed in the last few posts. It can work in some situations, but it sounds like it's proven more useful as a way to generate force from electricity rather than the other way around.

 

[sao123]

Originally posted by: Steg55
No it wouldnt work, we covered this in a physics lecture a while back.

I can't find me notes on it - sod.

Anyway - to break the flux lines with the wire you would have to dangle it off the satalite towards earth. Also, to produce the voltage needed to power the Space Shuttle, 110v, the wire would need to be 11km long if I remember my maths correctly and THEN, once you have managed all that, you have this long wire connected at one end to the satalite with a potential difference across it. Now, how do you complete the circuit and allow a current to flow? If you looped the wire back again it would be inducing a current flowing the other way giving a net result of 0. It wouldnt work.

Steg

Power the space shuttle??? Woah... back the train up a few hundred light years...
I said power a sattelite... not the space shuttle.
the difference is tremendous...like
powering your entire street vs powering 1 microwave oven

 

[DrPizza]

Originally posted by: sao123

Originally posted by: Steg55
No it wouldnt work, we covered this in a physics lecture a while back.

I can't find me notes on it - sod.

Anyway - to break the flux lines with the wire you would have to dangle it off the satalite towards earth. Also, to produce the voltage needed to power the Space Shuttle, 110v, the wire would need to be 11km long if I remember my maths correctly and THEN, once you have managed all that, you have this long wire connected at one end to the satalite with a potential difference across it. Now, how do you complete the circuit and allow a current to flow? If you looped the wire back again it would be inducing a current flowing the other way giving a net result of 0. It wouldnt work.

Steg

Power the space shuttle??? Woah... back the train up a few hundred light years...
I said power a sattelite... not the space shuttle.
the difference is tremendous...like
powering your entire street vs powering 1 microwave oven

But, he makes a good point about needing a loop to complete the circuit. Nonetheless, didn't they attempt to do some sort of experiment with something like this on the shuttle? IIRC, their wire got "stuck" when it was only partway untethered.

 

[Geniere]

The experiment has been done twice using the NASA shuttles. The winch failed in the first trial but several years later over 12 miles of cable was deployed. Very high currents at low voltages were recorded. After 5-6 hours, the cable snapped at the winch connection with a large shower of sparks.

 

[DrPizza]

Originally posted by: Geniere
The experiment has been done twice using the NASA shuttles. The winch failed in the first trial but several years later over 12 miles of cable was deployed. Very high currents at low voltages were recorded. After 5-6 hours, the cable snapped at the winch connection with a large shower of sparks.

Thanks. I was going to search for it, but was on the home computer (dial-up)... it's not worth searching for things sometimes

 

[Geniere]

A cable dangling from a satellite can be used for higher or lower altitude corrections via changing the center of mass. A variety of losses come into play so inevitably some type of active propulsion must make up for it. Systems of tethered satellites may use the energy loss or gain of one to change the orbit of another. A space elevator is being considered using the earth as one of the satellites and immensely strong carbon nano-tube cables.

 

[Geniere]

Originally posted by: DrPizza
home computer (dial-up)...

Yucky - but I'm old enough to remember the 16 baud modems and 5 bit com codes.

 

[Geniere]

Link to NASA re: power from satellite cable.

http://science.msfc.nasa.gov/newhome/headlines/ast08sep97_1.htm

 

[Armitage]

Originally posted by: Geniere
A cable dangling from a satellite can be used for higher or lower altitude corrections via changing the center of mass.

The mass of the tethers would have to be very large to effect an orbit change due to the change in CG. I haven't done the math, but I'd wager that a similar mass of fuel would get you a bigger orbit change with less complexity & risk then you encounter with tether dynamics. They have been proposed to assist in deorbiting LEO spacecraft due to the drag effect mentioned previously.

A variety of losses come into play so inevitably some type of active propulsion must make up for it. Systems of tethered satellites may use the energy loss or gain of one to change the orbit of another. A space elevator is being considered using the earth as one of the satellites and immensely strong carbon nano-tube cables.