EM as a means of propulsion?

I was thinking earlier today about how in space the only force that would impede a straight path of travel is gravity. So with this in mind, do you guys think it is feasable to use a giant electromagnet in space as a means of propulsion. Just line the ship up with the destination, accounting for the gravity of other spacial bodies for use as a sort of slingshot. Then use opposing forces of magnetism to hyperaccelerate the craft. I am fairly new to ATS, so I was wondering if you guys have any thoughts on this, its applications, feasability, or even if this has already been discussed.

First let me welcome you to ATS.

Ok now I have a question. Is the magnet inside the craft or outside. I serously do not see how such a scheme could work but if you could provite more details I might get a better picture of what you are trying to explain.

Thank you, I reread it and decided it was little vague. The magnet would be obitally mounted most likely, or possibly on the lunar surface. Although these aren't currently possible, I see these things within the grasp of science within the next 10-20 years. So to explain more on how it would work.

We use a conventional launch to reach the orbital platform/space station

The Orbital platform would have a fairly large electromagnet mounted on it, with a large protrusion from the middle of the magnet(this would serve as a method of guiding the craft. Here is a visual I just made. Click it so see a full size.

img5.exs.cx...

Isn't the technology already here? Isn't that how some amusement parks accelerate their rollercoasters from zero to ninty mph? Example: The incredible Hulk at Universal in Orlando.

I mainly meant have the orbital platforms/moon launch sites. We could probably be there if we wanted though.

I read this book as a kid: The Millennial Project: Colonize the Galaxy in 8 Easy Steps. It's a great book for inspiration, and as a general strategy for colonizing the solar system the overall approach the author suggests is much more thought out than anything I've seen elsewhere.

One thing he brings up, though, is basically what your picture suggests, if I'm reading it right:

at each major space travel "destination", you have what is essentially a giant double-barreled shotgun, except with an "in" and an "out barrel. Outgoing spacecraft are propelled out of the "out" barrel by using a pulsed electromagnet -- ie, the "out barrel" is a giant rail gun -- and the vehicle is sent off to whereever its going.

the "in" barrel does the same thing in reverse: one of the nifty things about electromagnetism is that a moving magnetic field induces electrical current in wire (which is how generators work), and thus if you have a long enough incoming barrel you can drain off the incoming vessel's kinetic energy by way of the induced current it makes.

since there's not much to slow you down in space -- not a lot of gas for friction, not too many strong gravity fields in deep space -- a vessel will retain most of its kinetic energy over the course of its journey, meaning that with reasonably efficient power reclamation facilities in the "incoming vessels" you could probably get back 80% or more of the energy originally given to the vessel you're slowing down. what this means is that on travels between destinations that have these stations, the total network is pretty energy efficient -- most of the energy put into going one way can be reused to send the ship back the other way, or to send another ship back home -- and for conventional propulsion (ie, chemical-based or nuclear-based) there's no equivalent way to reclaim your kinetic energy on landing.

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So, it's a very good idea, mainly because of the energy efficiency of a network of such propulsion devices. There are some engineering problems:

a) you can't really use a permanent magnet for your initial propulsion, because the ones that exist aren't sufficiently powerful; you need electromagnets that you can "pulse" power into, but unfortunately how to deliver large amounts of electrical current in very short amounts of time is a very difficult problem. there's been lots of research into it -- mainly for projects like railguns, which have both military and industrial applications -- but my understanding is that we're still a long ways off from being able to pulse enough power for space travel purposes, even if we assume we're starting from space.

b) this approach is really only that useful for trips to places you've already been; once the technology is there an electromagnetic push is still a better way to get going in a particular direction, but you'll still need to build in some kind of other propulsion devices to maneuver once you get there. without those, you're just riding a big bullet...

c) likewise, you'd still need some kind of propulsion onboard for course adjustments or unforeseen difficulties

d) lastly, EMP pulses can totally ruin electronic and computer equipment, even if the stuff isn't turned on (ie, it's not like in the matrix where you just turn off the ship and you're ok). so, if you got this approach working you'd have to shield all your onboard electronics and computer systems, and while not overly difficult it's a big hassle and adds weight and bulk to your ship.

all of these are just obstacles, and not reasons why EMP propulsion like you're suggesting can't work. if you'd like some really outside-the-box ideas on space travel and colonization, take a look at that book; it's very inspirational, even if a bit dated (and even though it doesn't take into account, say, the idea of a space elevator becoming feasible, which is looking more and more likely in our lifetimes if the funding and motivation are there for it).

d) lastly, EMP pulses can totally ruin electronic and computer equipment, even if the stuff isn't turned on (ie, it's not like in the matrix where you just turn off the ship and you're ok). so, if you got this approach working you'd have to shield all your onboard electronics and computer systems, and while not overly difficult it's a big hassle and adds weight and bulk to your ship.

Well thats sorta easy to answer, Optical based or Nanoscale Analog based both are increadibly fast and immune from EM as they don't work like traditional electronics, but its still on the drawing board at Intel and IBM, so it could be awhile before they release anything tangible in that area in the next year. Maybe by 2007-08...

Not to take this out of the outer space realm but what about an Electromagnetic Pulse Engine here on Earth to power autos? I know a man who has a working model of this engine. He was told it would not work by physicists, and then made the model to show them that it did, and they were amazed. He shielded the magnets with a type of Mu-metal to protect the electronics and such. He has many inventions he is trying to get off the showroom floor, but so far has only received a contract for one of them.

It wouldn't work in one giant pulse and the launch tower would need to have MANY coils so that the ship could be accelerated slowly enough so the G forces would be safe for the crew. But even still the ship would start to crumple because the high flux magnetic fields would try to compress the hull.

tesladownunder.iinet.net.au...
pictures of a can that was crushed by a high flux magnetic field and other fun stuff that can kill you.

i hadn't thought about the accelleration forces, but yeah; i think the book did, but even if it didn't all you have to do is have a much-much longer tube, and a bunch of magnetic rings each of which pulses on at the right time to give you another push. not being an engineer or a doctor i don't know either how long the tube would have to be or how much accelleration the body can withstand, but this difficulty seems like it could be worked around...it'd just be a pain in the rear.

NOT probable.
NOT feasible.

The amount of energy needed to use electromagnetism to shoot a rocket from Earth to the Moon would be enormous, not to mention it would disrupt the electronic equipment of entire countries.

Let's not forget the difference between magnetic fields and static fields.

Force generated by static fields (electric and gravitational) between two bodies aren't affected by distance as much as magnetic fields.

Magnetic fields are ALWAYS closed loops (if you can find one that isn't a closed loop, congrats, you've just discovered a monopole! Go collect your Nobel Prize :lol. This means that the equations used for force calculations depends VERY heavily on distance.

You'd sooner give people cancer and insomnia from those magnetic fields than move heavy arse rocket.

A much more feasible idea that we're already considering is a space elevator (made using CNT, a diamond wannabe; just as strong, a little more flexible).

if you create a triple emfield which are all adjusteble for that if you raise one fields strenght you can propel it away in a surten way.
and then if you have this fields use the external surface as a guidance and place it under high voltage (surface has to be highly superconducting)
the surface will create also an Em Field. then we know surten particals which can be taken into such a state that it goes faster as light.
project these particles into the surface of the craft it will captured into this field guided around it and then quantum entangle them onto other particles on the place were you wanna go.

but for you entangle create a map of know universe and place a raster over this map with squares of 1 by 1 lightyear and then you can say i want to go there that is the distance the inboard cpu calcutales distance and tries to detect inspace particles and then it will quantum entangle with these particles the ship inside the emshield of surface hyjacks on with the entangling particles for only the particles around the ship will entangle and then they will disapate with the craft intact on the its planned coordinates.

when in orbit the three other field projectors will create EM Fortex underneath the craft by using ways of spinning the three field and then it will use this fortex to navigate and propulsion for short distances.

notice this is highly theory and i just beginning to work it out.

Nox:

the amount of energy needed to shoot a rocket to the moon electromagnetically is the same (modulo efficiency of propulsion device) as to shoot a rocket to the moon chemically, so that point's not really valid...if anything, electrical generation can be made more efficient than energy extraction by means of combustion (think a couple nuclear power plants around your launch facility).

similarly, the advantage of a space elevator is that you use electrical energy to lift your spaceship up into earth orbit; the amount of energy required to do this with a space elevator (ignoring the energy cost of building and maintaining the elevator, etc.) is the same as needed for blasting something up into space by way of chemical rockets, so again the advantage of the space elevator is really the ease of generating the energy, not requiring less energy.

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what is a terrible idea is using some static electrical field to push a ship up to the moon (and using some permanent magnet or electromagnet to do the same is even more terrible, for the reasons you describe) because, yes, to continually push something that far using electronic or magnetic repulsion is woefully inefficient, and maintaining that field requires boatloads of energy...if that's what Grendelsbacon was suggesting, than yeah, it's totally impractical.

using something like a railgun to shoot a rocket into space is much more practical, though still a long ways off and of dubious safety for human passengers without some modification. using a railgun mounted at the end of a space elevator is an even better idea, because you can scale down the amount of electrical impulse needed dramatically by waiting to apply it until after you're most of the way out of the earth's gravity well. using something like the double-barrelled approach described in an earlier approach is smarter still for travel between already-visited destinations, because you can harvest the induced current from the decelerating incoming ships to make greatly reduce the systemwide need for energy (even if some stations with more outbound than inbound traffic still require lots of energy pumped into them on the spot).

if we've got space colonies in a couple hundred years, i'll metaphorically bet you good money that at least for passenger-free transportation the bulk of goods are transported using some version of the double-barrelled railgun approach described above, and possibly human transport will use a similar mechanism; the energy economics are just too good to ignore, mainly because no other currently hypothesized means of propelling objects provides as nice of a way to recover the incoming vessel's kinetic energy as they decelerate upon arrival.

i'm not sure about the amount of emp disturbance using a railgun approach like this would cause. certainly the immediate vicinity would need lots and lots of shielding if the equipment there is to survive the emp pulse accompanying a launch. if we were talking about using a static field (which again is a terrible idea, and a "permanent pushing magent" is even worse) than you'd almost certainly be correct in that the electronic fields put out would disrupt stuff over a couple hundred miles or so, but for a pulsed system -- especially a space-based pulsed system -- i suspect that local shielding will preserve the equipment and the health risks from exposure to the emp would be close to nil for all but the onsite staff (who, hopefully, would be automated for the most part).

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i'm not sure what the point of bringing up the fact that "magnetic fields are always closed loops" has to the problem at hand; using electromagnets to accellerate objects is pretty well established (it's how many paricle accellerators and railguns operate) and the feasibility of this approach doesn't depend on the existence or not of magentic monopoles, because the technology manifestly works.

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so yeah, if you're responding to the idea of using a fixed field -- either electric or (heaven forbid) magnetic -- to keep pushing an object all the way to its destination, you're absolutely right, but most of your objections don't apply to using something akin to a giant railgun or particle accellerator to provide an enormous impulse to your spacecraft all at once....that works, and you don't even need new physics to make an argument for it.

I thought there was research on the effects of magnetic fields on people and it proved it had no major effects on people

And, how will the EMP be dispersed over a wide area if the Electromagnetic "Rail" is very local?

I know little about how EMP acts so please bear with me...

And is it true that in space you infinitly accelerate? or do you actually decelerate?

sorry, i'm not too smart on science topics, I shouldn't have dropped out of school

@ sisonek:

I was assuming that he meant using electromagnetic pulse to push or pull a rocket to the moon (his diagram "TehRepresentation" REALLY didn't help much). That's why I nearly shot milk out of my nose when I first read the description.

What you're describing is just a really large "rail gun" (which is essentially just a really fast version of the elevator anyway), which sounds a LOT better than what I originally assumed the thread was about. It will still take an enormous amount of power. Also, everything within the vicinity would be affected.

I highly disagree that a space elevator would require as much energy as fuel combustion. Fuel combustion is extremely wasteful.

It would make more sense if we used some hybrid method, providing initial velocity to the rocket with a electromagnetic rail, and then providing the rest of the escape velocity with rocket fuel. That makes more sense until corporations finally give a rats arse about new "risky" technologies like CNT and start investing in mass production technologies for CNT.

@ GrOuNd_ZeRo:

Magnetic fields on people has minimal if any effect. However, take into the context that I originally thought GrendelsBacon was referring to electric or magnetic repulsion or attraction, not the more likely rail gun design sisonek is referring to.

Such an enormous magnetic field (if generated at all) would have unknown effects. They could be serious enough to affect the weather or create Auroras or all sorts of other funky crap.

I'm sure a magnet of that magnetude (ok... bad pun, ) would have some effects on people. Honestly, if a magnet was that strong a few pacemaker users might just roll over.

Wow, the response to this is awesome, thank you all for your input. I would like to say that I was thinking of a rail gun when I had this idea, but I don't know alot about their workings. One thing that probably made me forget this is that it had been about 8 hours between when I had the idea and posted. I had in in my first class of the day at school, so I would like to thank everyone for the replies. Also, where can I find more info on space elevators.

Google it.

I suggest looking for "carbon nanotubes space elevator".

Be creative.

EDIT: Or you could look for "CNT space elevator", whatever.

[edit on 2-12-2004 by Nox]

Nox: we're basically talking past each other...looks like we agree on just about everything. And yeah, a space elevator would have a much lower net energy cost over the long run in getting things to orbit (especially if you disregard the initial energy investment in setting the thing up) precisely because it's a far more efficient way to transfer energy than is using combustion, and moreover generating the energy to be transferred is more efficient also.

when i said "take the same energy" i meant simply that strictly speaking (ie, ignoring efficiency) the energy required to put a rocket in orbit fixed...once you throw in efficiency of energy sources, yeah, you need a lot less energy with a space elevator than with a chemical rocket because your utilization efficiency is a lot higher with the space elevator.

i think i assumed he meant a giant railgun based on tehrepresentation and the outlandishness of using a pusher plate, but all your objections to the pusher plate idea are spot on; that's an idea that really will never work.

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as for the giant railgun, that's exactly what i mean...i'm not sure how you'd solve the problem of having the emp pulse affect everything around it, other than:

A) put it in space at the end of the space elevator, and shield everything in range (still have to worry about passing satellites, though)
B) bury it underground (on earth, in the moon, etc.), maybe in an equatorially located extinct volcano...for launches from the earth to the moon, say, you don't need much more energy to launch something from 2-3 miles below ground than you do to launch it from ground level (though this is more significant if you're just going into orbit) and having a few miles of earth between the launch center and everything else makes the local shielding issue much less serious...though building that far underground is pretty expensive, too...although, also, a launch tube miles long means you have more time to accellerate the thing and it's therefore that much easier on the human passengers

Slow acceloration Space Elevators will be good for transporting fragile goods(ie people) to orbit. Rail Guns will be used to lauch satellites and cargo into orbit at high speed. IMHO. BTW Theoretical Physists are just now starting to poke and prod the nature of Inertia and how it relates to Mass and Gravity. Who knows what will come out of that reasearch Maybe some day we can dampen Inertia.

I feel this is a great idea but their are a few hole in this theory one the EM would attract space "junk" also i would my create problems for sattelit that come in to close proxcimity to the EM but other wise sounds good