Thought experiment: Giant magnet for cleaning up space

Thread Starter

wayneh

Joined Sep 9, 2010
16,399
Suppose we placed a large wire loop into orbit, say 10 miles in diameter. It’s plenty cold, so it’s superconducting. Then use a solar panel to get current flowing, say 1000A.

The magnetic field generated would be perpendicular to the plane of the loop. Any conductive, ie. metallic debris passing through the nearby region would experience eddy current braking. Any deceleration would send that piece of junk to a lower orbit and maybe a fiery end.

If this thing was in action long enough, it might have a useful impact on the cloud of junk up there.

Thoughts?
 

Papabravo

Joined Feb 24, 2006
14,389
Would that work on aluminum and other non-ferrous metals? Besides who wants a great cloud of uncontrolled junk filtering down through the atmosphere. The smaller pieces might burn up, but the bigger ones might land where we don't want them to land.
 

Thread Starter

wayneh

Joined Sep 9, 2010
16,399
Would that work on aluminum and other non-ferrous metals? Besides who wants a great cloud of uncontrolled junk filtering down through the atmosphere. The smaller pieces might burn up, but the bigger ones might land where we don't want them to land.
It does work on any conductor. And it’s all coming down eventually.
 

BR-549

Joined Sep 22, 2013
4,938
For that size and trouble of a project.....the magnetic property would leave a lot of flack. Such as paint, insulation or plastic.

Solar powered, suitcase size tracking radars with MW or laser cannon.

What would heating a piece of flack do? Would it alter is course? Would it be adding mass?

Maybe just vaporize the smaller pieces.
 

WBahn

Joined Mar 31, 2012
26,141
Suppose we placed a large wire loop into orbit, say 10 miles in diameter. It’s plenty cold, so it’s superconducting. Then use a solar panel to get current flowing, say 1000A.

The magnetic field generated would be perpendicular to the plane of the loop. Any conductive, ie. metallic debris passing through the nearby region would experience eddy current braking. Any deceleration would send that piece of junk to a lower orbit and maybe a fiery end.

If this thing was in action long enough, it might have a useful impact on the cloud of junk up there.

Thoughts?
Why would it be plenty cold? The sun would heat it up, as would radiation from the Earth and the moon. Even if it was cold, why would that make it superconducting?

Remember that any force it exerts on another object is going to be reciprocated. So you are just as likely to deorbit your magnet instead of the junk.

Even in low Earth orbit, a ten mile diameter hoop, including the volume over which it has any appreciable effect, is insignificant compared to the volume of space.
 

oz93666

Joined Sep 7, 2010
737
This is a solution looking for a problem ....

There is no space-junk hazard .... sure there's numerically a great deal going around Earth at orbits of all distances , but the volume of space is so huge it doesn't pose a significant risk ....

Slightly similar to mid air collisions of aircraft a chance in a trillion trillion ...alarm bells ring if they come within a mile of each other !

And the asteroid belt ... looking at artists renditions the impression is given of a great swarm of bodies and you would be risking life and limb to go through it .... when you do the actual numbers there's almost zero hazard the asteroids are spaced many 10's of thousand miles apart.

Fanciful depiction of the asteroid belt
 
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Glenn Holland

Joined Dec 26, 2014
705
This is a solution looking for a problem ....

There is no space-junk hazard .... sure there's numerically a great deal going around Earth at orbits of all distances , but the volume of space is so huge it doesn't pose a significant risk ....

Slightly similar to mid air collisions of aircraft a chance in a billion billion ...alarm bells ring if they come within a mile of each other !
Man made space hardware is designed to disintegrate upon entering the atmosphere so there's no hazard in the lower atmosphere. However, there are meteors and asteroids lurking out there that we must keep tabs on.
 

oz93666

Joined Sep 7, 2010
737
Man made space hardware is designed to disintegrate upon entering the atmosphere so there's no hazard in the lower atmosphere. However, there are meteors and asteroids lurking out there that we must keep tabs on.
Well that's another issue , but again IMHO not a significant danger ... And how exactly can we keep tabs on them?? with what purpose??

Meteors ... by definition have already entered earths atmosphere and are burning up .... they shower the earth constantly from small dust grain size to larger , nothing we can do to stop them or avoid them ...

Asteroids ... are space rocks from the asteroid belt ,,,, If a big space rock was heading our way I'm sure we could cope with the impact , cos we have no way of stopping it ( except in movies).

TS needs to clarify what exactly he's concerned about , I suspect it's man made items impacting skylab or satelights etc....a non issue.

As for TS's idea of a 10 mile coil. You have the challenge of keeping the 31.14 mile length of wire cold when the sun is shining on it , and the coil's diameter is so big the magnetic field generated would be insignificant . The field required would be unimaginably large in order to decelerate a fast moving object during the split second it passed through the coil . The moment the coil was switched on there would be an enormous pull from Earths own field which would cause it to crash into one of the Earths polls .... But suppose it could neutralise everything passing through it , a 10 mile circle is tiny compared to the volume of space under consideration .
 
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Thread Starter

wayneh

Joined Sep 9, 2010
16,399
Why would it be plenty cold?
The sun would heat it up, as would radiation from the Earth and the moon.
I have to admit ignorance on this issue. Would it not be possible to shade the wire itself, and keep its temperature below the superconducting critical temperature?
Even if it was cold, why would that make it superconducting?
Well obviously it would need to be made of the proper material to become superconducting at the relevant temperature.
Remember that any force it exerts on another object is going to be reciprocated. So you are just as likely to deorbit your magnet instead of the junk.
Definitely true, and I envision the hoop as not completely passive. It would need to change position from time to time and to compensate for the drag due to successful encounters. I imagine that it should probably spin, to help it hold it's circular perimeter.
Even in low Earth orbit, a ten mile diameter hoop, including the volume over which it has any appreciable effect, is insignificant compared to the volume of space.
I do appreciate how meager just one of these would be. If it actually worked, I suppose there could be several of them. Could they have a positive cost benefit ratio? Probably not unless there is very cheap transport costs into orbit.
 

Thread Starter

wayneh

Joined Sep 9, 2010
16,399
For that size and trouble of a project.....the magnetic property would leave a lot of flack. Such as paint, insulation or plastic.
True, but I suppose that category of junk is less dangerous than pieces of metal. Maybe there's more of it, though. I'm not really sure of the composition of space junk.
Solar powered, suitcase size tracking radars with MW or laser cannon.

What would heating a piece of flack do? Would it alter is course? Would it be adding mass?

Maybe just vaporize the smaller pieces.
A laser seems like a possible solution but not without problems. One problem is unintended targets - the beam is going to be dangerous far past whatever the target is. Multiple laser triangulation might help with that. No one beam would be devastating but crossing the streams on the target would zap it. But the mass would still be there, and now it would be smaller and harder to track. Filling orbital space with vaporized paint and plastic seems like not much of a solution.
 

Thread Starter

wayneh

Joined Sep 9, 2010
16,399
The moment the coil was switched on there would be an enormous pull from Earths own field which would cause it to crash into one of the Earths polls ....
That's definitely one of the major hurdles. I have no idea how big a factor that would be and whether it would be possible to design ways to counteract it by orientation of the hoop.
 

oz93666

Joined Sep 7, 2010
737
Glancing through those 3 articles . I'm more convinced than ever this is another exaggerated doom and gloom issue .... The scientists are looking for more funding and job security in this area , and the magazines have to fill pages ....

Looking carefully at the articles "scientists predict" and "May have underestimated the problem" ... lots of perhaps , maybes and projections ... The only picture posted in these articles of damage is this one .....



But when you read the caption it was caused over 20 years ago when Russia's Mir Space Station incurred damage after a collision with a resupply ship ....Not collision with space Junk ..lol ( they know no ones paying attention)

The articles all highlight the 'danger' to satelights ,since around 500 new ones are being launched each year , well that is a lot of satelights... so sooner or later we might get a killer impact ... they normal have insurance , we can just send up a new one.

But as for the coil ... Is anyone interested enough to calculate what sort of magnetic field could be generated by a 10 mile coil??

We tend to think the sky's the limit with super conductors ... Certainly MRI's develop quiet a good field , but I suspect space junk passing through it would not be perturbed too much ... and that coil is only a few meters diameter .... the bigger the diameter gets the weaker the field , At 10 miles diameter I would bet the field would be pitifully small.

 
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oz93666

Joined Sep 7, 2010
737
In 1993 NBS produced this rigged video ...

It ended up damaging their reputation ...
lol ...you couldn't make that up !!! ...they placed "incendiary devices , overfilled the gas tank , and fitted the wrong fuel tank closure" ...Notice only an apology from NBS , no police investigation, or trail for conspiracy !

But they were only exposed because of a fire chief , and the motor company had a reputation to protect ..

I see a great many suspicious news articles , but because no one has a financial interest in exposing them , they go unchallenged .
 

Thread Starter

wayneh

Joined Sep 9, 2010
16,399
But as for the coil ... Is anyone interested enough to calculate what sort of magnetic field could be generated by a 10 mile coil??
I think the comparison to Earth's magnetic field would be interesting. It seems to me that Earth's field should already provide a degree of eddy-current braking to any conductors passing through it. I've never heard anyone talk about this, so I guess the effect is very weak? But the field is really, really big and should eventually send any metal to its doom.
 

WBahn

Joined Mar 31, 2012
26,141
I think the comparison to Earth's magnetic field would be interesting. It seems to me that Earth's field should already provide a degree of eddy-current braking to any conductors passing through it. I've never heard anyone talk about this, so I guess the effect is very weak? But the field is really, really big and should eventually send any metal to its doom.
Earth's magnetic field does interact with satellites, but not very strongly. The satellite would need to be about 50 m long before the electromagnetic drag would start exceeding the friction drag in low Earth orbit.
 

nsaspook

Joined Aug 27, 2009
7,586
I think the comparison to Earth's magnetic field would be interesting. It seems to me that Earth's field should already provide a degree of eddy-current braking to any conductors passing through it. I've never heard anyone talk about this, so I guess the effect is very weak? But the field is really, really big and should eventually send any metal to its doom.
The total field (of the earth or maybe a space junk coil) might be big but the local field cross-section for di/dt electromagnetic damping to any one piece of space junk will be tiny in relation to the KE of the moving object in most cases. The total magnetic field stores most of the energy into X volume of space near the magnetic field source so take the volume of the objects size with consideration to construction, orientation (tumbling) and trajectory (crossing field lines) into that field for a fraction (eddy current torque is inversely proportional to the square of the distance) of possible slowing energy.

One type of damping system.
https://courses.lumenlearning.com/physics/chapter/23-4-eddy-currents-and-magnetic-damping/
 

WBahn

Joined Mar 31, 2012
26,141
Glancing through those 3 articles . I'm more convinced than ever this is another exaggerated doom and gloom issue .... The scientists are looking for more funding and job security in this area , and the magazines have to fill pages ....

Looking carefully at the articles "scientists predict" and "May have underestimated the problem" ... lots of perhaps , maybes and projections ... The only picture posted in these articles of damage is this one .....

But when you read the caption it was caused over 20 years ago when Russia's Mir Space Station incurred damage after a collision with a resupply ship ....Not collision with space Junk ..lol ( they know no ones paying attention)

The articles all highlight the 'danger' to satelights ,since around 500 new ones are being launched each year , well that is a lot of satelights... so sooner or later we might get a killer impact ... they normal have insurance , we can just send up a new one.
You keep talking like no collisions with debris have ever happened and that the odds of it ever happening are too low to even be concerned about.

While I agree that the risk is often exaggerated, more often than not by ignorant media folks, the simple fact is that it HAS happened and more than once.

The first documented case was in 1996 the French had a recon satellite hit and severely damaged by debris from an unrelated Ariane rocket that was cataloged space debris.

The Russians had a comm satellite rendered inoperable in 2006 by impact with space debris.

The Iridium satellite constellation (about 60 satellites) has to content with about 50 cases each DAY of passes of other objects within 5 km of one of its birds and has to decide whether to move it (using up the very finite amount of maneuvering fuel on board) or take the risk of a collision. In 2009 they had a report that a defunct Russian bird would pass within 600 m of one of their satellites and since it was one of their oldest it had very little fuel left, so they opted not to move it. The two collided at well over 20,000 mph and the resulting debris plume has been causing problems ever since, with the ISS having to execute evasion maneuvers more than once.

There were two collisions between satellites and space debris in the first half of 2013.

It is estimated that, even out in geostationary altitudes, that defunct satellites pass within 50 m of active satellites about once a year.
 
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