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coilgun spacecraft

a spacecraft blasted through an elecromagnetic ring
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with all the ideas going around about how we can get to other planets quickly without using a lot of fuel, you begin to thing...why do we need it? my proposal is to construct electromagnetic rings in space, powered by solar panels channeled to batteries, or capaciters. The ship itself will only have small ion engines for course corrections and going to he ring. these rings will be spread out distances between where we are and where we want to go. ie: five on the way to mars, 2 to accelerate 1 to stabalize, and 2 to deccelerate.

Earth to Mars O I I I I I o

The ship will also have an electromagnetic generator on the fron and rear of the craft and a computer (linked to the rings) will control the on/off switch. the rings will have their own ion engines hooked to computers to help them stay in line. when the ring is on and the electromagnetic generator on the ship is on. (opposite charges of course...) the ring will pull the ship foward at a large speed. just before the ship gets to the ring the electronics on both will shut off. after the ship is through the electronics will come on again, this time both the ring and the ship are using the opposite pole of the magnet (because all magnets have two poles) this will pull the ship foward at high speed then push it away at high speed. this will continue for the next ring. the ring after that will be used just to make sure the path to the next ring is straight and the fourth ring will use less power and the SAME charge as the ship to gradually slow it down but not to a stop. the LAST ring will stop the ship and then it can travel with its own engines, the little way to the planet,space station, ect. for the return home the ship will fly backwards and all charges on the rings will be reversed.the ship will NOT enter atmosphere on any planet, it will be used for transportation. this will require the rings to be made in space and positioned through normal power...(with an unmanned or manned vehicle) thell me if this is baked or not, i'm just a 17 year old kid from Texas.

Falcion, Oct 06 2003

About Ion Engines (NASA) http://science.nasa...s/prop06apr99_2.htm
[Reverend_Cobol, Oct 04 2004, last modified Oct 21 2004]


       A few problems here.   

       See, Earth and Mars, well... they're moving around the Sun... and not at the same speed.   

       Second problem: Ion engines aren't that strong.
Cedar Park, Oct 06 2003

       Read Ringworld by Larry Niven. But you have a very good idea and I think you will enjoy his books.   

       Everyone wants a tasp. :)
sartep, Oct 06 2003

       There is the added problem that strong magnetic fields will create eddy currents in the metal of the spacecraft, which will heat it up. So in accelerating your spaceraft you may melt it.   

       When I was at school, I often wondered if there was anyone out there who was actually called Eddie Currents.
parky, Oct 06 2003

       Don't the laws of momentum (specifically Newton's third law) apply in space? If for every action there is an equal and opposite reaction then the rings will quickly be pushed out of position, making this a one use only system.
suctionpad, Oct 06 2003

       [suctionpad]: That's a third problem. Glad you thought of that. You'd need a set of rings with enormous mass to keep even a semblance of stability.
Cedar Park, Oct 06 2003

       Or you could get them to spin amazingly fast so that its gyroscopic forces stop it from flying backwards. And with a small nuclear reactor you can power the rings and move them by vaporising the waste and using a high powered ion engine.
angry_scientist, Nov 04 2003

       Actually the gyroscope idea won't keep the ring from flying backwards since that direction is perpendicular to the direction of rotation (assuming by spin you ment clockwise or ccw about it's center of mass, and not spinning like a washer on a table top). Spinning it quickly would keep the ring from turning about it's axis like a washer on spining on a table, but this is bad since we want the ring to be able to rotate at a precalulated velocity so that it is always facing the flight path perpendicular to the ring (i.e. we don't want the ring throwing our spacecraft off the flight path).   

       Now ion engines have been brought up alot in the other annotations so I thought I'd clear something up. Yes, ion engines can propell a craft to amazing speeds, however, the actual thrust output of an ion engine is very poor (see link). Current technology can only muster about the same thrust as a few sheets of paper resting on your hand. Ion engines are not the way to perform course corrections in space unless you have a few months to do it, and getting a row of massive rings to stay in proper orbit between earth and mars requires just a little more responsiveness than a few months.   

       Suctionpad is right, and his argument was the first that I thought of when reading this post. The rings would have to be massive in relation to the spacecraft, and contain one massive set of engines to keep them from either being attracted to the spacecraft, or thrown backwards as it propels said craft foreward. In a (near)frictionless environment like space. Anyone who has ever fired a shotgun can attest to this fact, and it is doubly more so in space since you're not firmly anchored to the earth by the friction of your feet. No matter how fast the craft is going initially, you're still going to have to absorb the relative extra push you give it with the ring, even if you only pulse a massive burst of current through it as the craft enters the ring itself.   

       I'm not going to argue about the ability of mankind to fire a spacecraft through a set of rings orbiting in space at [BLAH] Km/sec, assuming you could keep them in a proper orbit, which, btw wouldn't have to be a straight line UnaBubba*. We've been making trick shots for centuries.   

       Lastly, to address Eddy currents, you could construct your ship of basically a hollow shell of superconducting metal (space is fairly cold, and current sc reasearch is yielding some fairly warm sc metals) since basically all you're doing is firing a bullet from earth to mars. If you have a simple enough engine system, with some manner of magnetic shielding around the sensitive bits (not sure how you'd accomplish this) you could get away with some pretty huge magnetic fields in the rings. Of course you wouldn't be able to have anything onboard that would be susceptible to melting due to induced currents, but I think that the effects this problem could possibly be at least greatly reduced.   

       *Each ring would only have to be at the proper place to accelerate the spacecraft on it's filght path, and then only for an instant, so technically, if you timed it right, you could have the rings in a sort of a trailing orbit, getting closer and closer to a straight line as you approached mars. This is because you're not travelling at a constant linear velocity, but rather increasing it as you go. Think about it with equidistant rings, the math works out.   

       Sorry about being so wordy, i kinda went off there...
Reverend_Cobol, Nov 04 2003

       If you sent equal traffic both ways, the rings might not be pushed too far.
Tranai, Feb 18 2004

       A major sheduling problem will be the differential orbital velocities. Each ring as we move away from the sun will orbit the sun at progressively longer periods. With one set of rings, they will only line up for a shot at your target very rarely. The obvious halfbaked (and very expensive) answer to this problem is to place multiple rings in each orbit, spaced at equal distances. Each higher orbit should have more rings than the lower, with enough rings to line us up for a Mars shot no less than once per opposition.   

       We will have to need to move an AWFUL lot of payload to justify the expense and effort of building, placing, operating, and servicing this amount of infrastructure. As we get higher up, solar power becomes less and less effective as a means to power these rings too.   

       Giving it a bun anyway. The idea appeals to my Niven/Asimov/Bradbury side.
gardnertoo, Jul 03 2004

       I like it and it reminds me of the rings used in Babylon 5 without the hyperspace part, so maybe you could add that later. :-) All the comments are correct, that the rings would have to be massive in comparison to the ships mass. I see it as converted asteroids guided into orbit with either ion engines or solar sails. The orbital mechanics issues are tough, though possibly simplified by the need to only use the system during specific Mars-Earth alignments, but I think this has more applications than Earth-Mars-Earth, it is an infrastructure that could be continually be expanded for all destinations.
MisterQED, Oct 25 2007

       What if the magnetic rings were to push each other into the next, pancake style, carrying the ship along with them.   

       This way you would lose the first ring, but the 2nd would travel with your ship to the third, which would stop the 2nd ring, and continue with your ship to the 4th etc.   

       Ths way you wouldn't have to lose all your rings.   

       Maybe if the first ring was incporporated with the moon as well. It's got some mass I hear.
Giblet, Oct 25 2007

       Here's a much simpler version: simply have a long coilgun in earth orbit, on a rigid tubular frame, instead of rings floating off separately and scattered between earth and the destination. First off, that means you don't need multiple ring pathways, because the coilgun will orbit earth every 90 minutes; if you want to go to Mars, you launch the craft when the coilgun is pointing in the direction of earth's forward orbit, adding additional solar-orbit velocity so the payload spirals outward; if you want to reach the inner solar system, just wait 45 minutes until it's pointing the opposite way. If you want to reach different destinations, just vary the force on each coil segment to achieve different delta-Vs.   

       A coilgun that can deliver a delta-V of 10km/s at tolerable accelerations will be over 1000km long, but it would still be easier to build and maintain than scattered rings all over the solar system, and there's no difficulty with aiming from one ring towards the next one. Another advantage is that you can fire it in reverse, taking a payload in orbit and slowing it down to zero velocity at the top of the atmosphere within minutes; then you can just use small retro rockets in combination with parachutes to land the craft, without having to deal with the complexities and dangers of atmospheric braking.
scottinmn, Nov 01 2008


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