These EMFF rings look interesting. What is the limits/potentials of this sort of design? With 0 gravity involved, could this be used in a system for sending payload beyond earth orbit, say?

RINGS propels satellites without propellants

Electromagnetic formation flight (EMFF) gets around this propellant problem by turning the satellites in a formation into electromagnets. By using a combination of magnets and reaction wheels, spacecraft in formation can move and change their attitude and even spin without propellant. Satellites can change their polarity to attract or repel one another, turn, or shift their relative positions in any manner that doesn’t require changing the center of gravity for the entire formation.

According to an MIT study , when EMFF is perfected, it will have a wide number of applications including interferometers, space telescopes where each satellite carries a section of mirror, generating artificial gravity, creating a magnet shield against solar radiation storms, and clearing space debris by using their spin to toss the debris into a safer trajectory. However, there is still a great deal of work to do because EMFF will need superconducting wires, high-velocity reaction wheels, cryogenic cooling, and other critical technologies to be developed before they become practical.

This bit is the key limitation on the system:

Satellites can change their polarity to attract or repel one another, turn, or shift their relative positions in any manner that doesn’t require changing the center of gravity for the entire formation.

The Rev Dodgson said:

This bit is the key limitation on the system:

Satellites can change their polarity to attract or repel one another, turn, or shift their relative positions in any manner that doesn’t require changing the center of gravity for the entire formation.

What if you had a formation of these in orbit and aligned the trajectory of another similarly equipped vehicle to intercept the formation. Could you have sufficient momentum in a stable formation, to transfer momentum from the that formation to the smaller mass of the passing payload, boosting the payloads orbit and leaving a formation that requires minimal adjustment to it’s orbit?

Guess I’m thinking if you had a long enough formation of these you might use them like a rail gun?

if the magnetic satellite system is moving things, then the satellites will be moving too

to every force……

wookiemeister said:

to every force……

hides head in hands

Riff-in-Thyme said:

wookiemeister said:

to every force……

hides head in hands

any chance an etch-a-sketch app can be added to this forum?

Riff-in-Thyme said:

Guess I’m thinking if you had a long enough formation of these you might use them like a rail gun?

bullet goes one way where does the rail go?

Riff-in-Thyme said:

Guess I’m thinking if you had a long enough formation of these you might use them like a rail gun?

bullet goes one way where does the rail go?

Riff-in-Thyme said:

Guess I’m thinking if you had a long enough formation of these you might use them like a rail gun?

bullet goes one way where does the rail go?

wookiemeister said:

Riff-in-Thyme said:

Guess I’m thinking if you had a long enough formation of these you might use them like a rail gun?

bullet goes one way where does the rail go?

The ‘rail’ would hypothetically consist of enough of these to create a magnetically controlled tunnel that is long enough to guide a single small object out of orbit.

I was also wondering if these could be used in conjunction with the earths magnetosphere(computer guidance has made it possible to control systems that are too sensitive for human piloting)

Scenario 3: If a large enough formation of these was positioned so that they made a stable orbiting ring around the Earth, would it have enough propulsion control to lower a ‘sea-monkey’ type chain into the Earth’s atmosphere?

I posted this thread mostly out of interest in the maths involved. Any chance you could give a greater than yes or no answer to the formation hypothesised here PM? These are obviously intended for smaller formations but since these are essentially guided bucky balls I was wonder how far they could be pushed if scale of deployment were no obstacle.

Seemed like a good maths game to me. shrug

The Rev Dodgson said:

This bit is the key limitation on the system:

Satellites can change their polarity to attract or repel one another, turn, or shift their relative positions in any manner that doesn’t require changing the center of gravity for the entire formation.

I gather that you want to electromagnetically launch stuff from an Earth satellite into deep space. Is that correct?

The problem (as TRD mentioned in the quote above) is that the techniques in the OP don’t change the centre of mass of the satellite ensemble. You can’t get around the law of conservation of momentum.

So if you want to launch stuff without disturbing the orbit of your satellite, then you need to shoot some other stuff with equal and opposite momentum. You could do that by putting a rocket engine on your satellite, but that kinda defeats the purpose of your electromagnetic launch mechanism. Alternatively, you could launch payloads in pairs that go in opposite directions. That’s not much use for one-off launches, but it could be quite practical if we had a whole bunch of orbital habitats sending stuff to each other on a regular basis.

PM 2Ring said:

The Rev Dodgson said:

This bit is the key limitation on the system:

Satellites can change their polarity to attract or repel one another, turn, or shift their relative positions in any manner that doesn’t require changing the center of gravity for the entire formation.

I gather that you want to electromagnetically launch stuff from an Earth satellite into deep space. Is that correct?

The problem (as TRD mentioned in the quote above) is that the techniques in the OP don’t change the centre of mass of the satellite ensemble. You can’t get around the law of conservation of momentum.

So if you want to launch stuff without disturbing the orbit of your satellite, then you need to shoot some other stuff with equal and opposite momentum. You could do that by putting a rocket engine on your satellite, but that kinda defeats the purpose of your electromagnetic launch mechanism. Alternatively, you could launch payloads in pairs that go in opposite directions. That’s not much use for one-off launches, but it could be quite practical if we had a whole bunch of orbital habitats sending stuff to each other on a regular basis.

Not so much. I was thinking more of a formation of these rings that extended entirely around the planet at a ‘suitable’ orbiting distance. Imagination not being limited by obstacles like funding, what systems could be devised using these in a way that effectively makes the earth the centre of gravity of the formation?

Would it even be theoretically possible to have a ring formation of these around the earth so that formation can use the earth as a center of gravity?

Riff-in-Thyme said:

PM 2Ring said:

I gather that you want to electromagnetically launch stuff from an Earth satellite into deep space. Is that correct?

Not so much. I was thinking more of a formation of these rings that extended entirely around the planet at a ‘suitable’ orbiting distance. Imagination not being limited by obstacles like funding, what systems could be devised using these in a way that effectively makes the earth the centre of gravity of the formation?

What sort of systems are you talking about, then?

Creating some sort of ring formation right around the planet isn’t going to make the conservation of momentum problem go away. However, the greater the mass of the launch “platform” the smaller will be the perturbation in its velocity when a payload of a given mass is launched because momentum = mass × velocity.

I did not provide a very clear idea of what I was suggesting here. The exercise requires that these magnetic rings are developed to the point where they can behave in space similar to the synchronised quadrotor swarms recently developed and can exert a strong enough force between each other that they are substantially difficult to separate. From there the challenge was to explore the possible applications that might be developed through various scales of formation or even through formations that might apply the electromagnetics available in a unique manner.

The orbital ring formation presented a design I thought might find some uses. If these can correct each others positions magnetically, wouldn’t that mean that a ring formation around the earth could be slowed or sped up above and below the velocity that a free mass would require to maintain the same orbit?

If this ring formation were tubular, could it be used to guide a payload to a velocity that would send it beyond earth orbit?

disclaimer as I mentioned earlier in the thread, this is just a buckeyball game for the imagination. this EM-ring guidance system just seemed to have more “theoretical” potential than the article seemed to give it credit for

Riff-in-Thyme said:

The orbital ring formation presented a design I thought might find some uses. If these can correct each others positions magnetically, wouldn’t that mean that a ring formation around the earth could be slowed or sped up above and below the velocity that a free mass would require to maintain the same orbit?

If this ring formation were tubular, could it be used to guide a payload to a velocity that would send it beyond earth orbit?

As I said above:

Creating some sort of ring formation right around the planet isn’t going to make the conservation of momentum problem go away. However, the greater the mass of the launch “platform” the smaller will be the perturbation in its velocity when a payload of a given mass is launched because momentum = mass × velocity.

Yes, a ring formation around the earth could be slowed or sped up above and below the velocity that a free mass would require to maintain the same orbit. Thus you can effectively use the ring as a store of kinetic energy. But bear in mind that such ring formations are not gravitationally stable: if they drift out of place for some reason they don’t self-correct gravitationally, they have to be moved back into place, and if you don’t act quickly to get them back “on track” they tend to accelerate in a disastrous fashion.

I suppose such a ring could harvest energy from the Earth’s magnetic field, and with careful manipulation, it could even exchange momentum with the Earth via the magnetic field interaction, so using it a launch platform wouldn’t perturb its orbit.

Happy now?

PM 2Ring said:

Riff-in-Thyme said:

The orbital ring formation presented a design I thought might find some uses. If these can correct each others positions magnetically, wouldn’t that mean that a ring formation around the earth could be slowed or sped up above and below the velocity that a free mass would require to maintain the same orbit?

If this ring formation were tubular, could it be used to guide a payload to a velocity that would send it beyond earth orbit?

As I said above:

Creating some sort of ring formation right around the planet isn’t going to make the conservation of momentum problem go away. However, the greater the mass of the launch “platform” the smaller will be the perturbation in its velocity when a payload of a given mass is launched because momentum = mass × velocity.

Yes, a ring formation around the earth could be slowed or sped up above and below the velocity that a free mass would require to maintain the same orbit. Thus you can effectively use the ring as a store of kinetic energy. But bear in mind that such ring formations are not gravitationally stable: if they drift out of place for some reason they don’t self-correct gravitationally, they have to be moved back into place, and if you don’t act quickly to get them back “on track” they tend to accelerate in a disastrous fashion.

I suppose such a ring could harvest energy from the Earth’s magnetic field, and with careful manipulation, it could even exchange momentum with the Earth via the magnetic field interaction, so using it a launch platform wouldn’t perturb its orbit.

Happy now?

EXTREMELY!!! :D

Riff-in-Thyme said:

EXTREMELY!!! :D

Thanks

Riff-in-Thyme said:

PM 2Ring said:

Yes, a ring formation around the earth could be slowed or sped up above and below the velocity that a free mass would require to maintain the same orbit. Thus you can effectively use the ring as a store of kinetic energy. But bear in mind that such ring formations are not gravitationally stable: if they drift out of place for some reason they don’t self-correct gravitationally, they have to be moved back into place, and if you don’t act quickly to get them back “on track” they tend to accelerate in a disastrous fashion.

I suppose such a ring could harvest energy from the Earth’s magnetic field, and with careful manipulation, it could even exchange momentum with the Earth via the magnetic field interaction, so using it a launch platform wouldn’t perturb its orbit.

hehe. wish I understood the subtleties of EM a bit better

Riff-in-Thyme said:

Riff-in-Thyme said:

EXTREMELY!!! :D

Thanks

No worries.

PM 2Ring said:

Riff-in-Thyme said:

Riff-in-Thyme said:

EXTREMELY!!! :D

Thanks

No worries.

I think my imagination has a sense of responsiblity and needs permission to explore some ideas! :P