# Couldnt a Magnet be used to throw objects into orbit? **URL:** \ **Category:** Factual Questions\ **Created:** [January 28, 2009, 6:54pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412 "2009-01-28T18:54:21Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Frodo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/frodo/32/302_2.png) [@Frodo](https://boards.straightdope.com/u/Frodo)\ **Post date:** [January 28, 2009, 6:54pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412/1 "2009-01-28T18:54:21Z")
Inspired by the “Strongest Magnet” thread. Well, could a magnet be used to do that?, supose you build a very strong electro magnet, then put another one on top so they repulse each other and activate both, could such a device be used to put objects in orbit?, would it be cheaper than the current chemical rocket method?. ---
**Author:** ![Keeve](https://avatars.discourse-cdn.com/v4/letter/k/f07891/32.png) [@Keeve](https://boards.straightdope.com/u/Keeve)\ **Post date:** [January 28, 2009, 7:02pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412/2 "2009-01-28T19:02:20Z")
It would be difficult to aim straight. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [January 28, 2009, 7:02pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412/3 "2009-01-28T19:02:30Z")
Research is being done, but don’t hold your breath. The typical launching device is a type of [railgun](http://en.wikipedia.org/wiki/Railgun). There are lots of engineering problems to overcome. ---
**Author:** ![BrotherCadfael](https://avatars.discourse-cdn.com/v4/letter/b/977dab/32.png) [@BrotherCadfael](https://boards.straightdope.com/u/BrotherCadfael)\ **Post date:** [January 28, 2009, 7:05pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412/4 "2009-01-28T19:05:33Z")
Check out the magnetic catapult in Heinlein’s _The Moon is a Harsh Mistress_, for the classic science fiction treatment of this idea. Although, as **beowulff** said, don’t hold your breath. ---
**Author:** ![Frodo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/frodo/32/302_2.png) [@Frodo](https://boards.straightdope.com/u/Frodo)\ **Post date:** [January 28, 2009, 7:07pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412/5 "2009-01-28T19:07:07Z")
> [@Keeve](#): > > It would be difficult to aim straight. why? ---
**Author:** ![brewha](https://avatars.discourse-cdn.com/v4/letter/b/91b2a8/32.png) [@brewha](https://boards.straightdope.com/u/brewha)\ **Post date:** [January 28, 2009, 7:07pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412/6 "2009-01-28T19:07:13Z")
The biggest issue is the acceleration. The space shuttle acclerates for eight and a half minutes. Even if you use a rail gun, you’d have to accelerate your object to escape velocity in less than a second. The forces would be huge. ---
**Author:** ![Frodo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/frodo/32/302_2.png) [@Frodo](https://boards.straightdope.com/u/Frodo)\ **Post date:** [January 28, 2009, 7:10pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412/7 "2009-01-28T19:10:01Z")
Why is a railgun needed?, wouldnt the crude device I mentioned work better?, I guess there is a limit to the force you can give to a magnet that prevents doing it?. ---
**Author:** ![Frodo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/frodo/32/302_2.png) [@Frodo](https://boards.straightdope.com/u/Frodo)\ **Post date:** [January 28, 2009, 7:11pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412/8 "2009-01-28T19:11:34Z")
> [@brewha](#): > > The biggest issue is the acceleration. > > The space shuttle acclerates for eight and a half minutes. Even if you use a rail gun, you’d have to accelerate your object to escape velocity in less than a second. The forces would be huge. If you wanted to send people they’ll get squashed, but couldnt it be used to send heavy objects, like metal for space stations and so on, and use the shuttle to send delicate things (like computers and humans?) ---
**Author:** ![ivn1188](https://avatars.discourse-cdn.com/v4/letter/i/e480ec/32.png) [@ivn1188](https://boards.straightdope.com/u/ivn1188)\ **Post date:** [January 28, 2009, 7:24pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412/9 "2009-01-28T19:24:01Z")
> [@brewha](#): > > The biggest issue is the acceleration. > > The space shuttle acclerates for eight and a half minutes. Even if you use a rail gun, you’d have to accelerate your object to escape velocity in less than a second. The forces would be huge. Why? If you can build a railgun, you can presumably build a really long railgun and stretch out the acceleration period. An evacuated tube gun that projects into the atlantic for a few hundred miles has been theorized as a low cost launch system. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [January 28, 2009, 7:24pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412/10 "2009-01-28T19:24:17Z")
There’s a basic orbital mechanics problem that no has mentioned yet that makes this impossible. You cannot launch an object into a sustainable orbit with a single impulse (as opposed to a continuous acceleration, like that supplied by a rocket), unless the object is already at orbital altitude. The reason for this is that a single impulse (like a shell launched from a cannon), can, at best, only put an object into an orbit that intersects the launch point. So any object launched from a given point on the surface of the Earth is either going to hit the surface of the Earth at some other point, or at best, is going to make one orbit that terminates at the launch point. So your hypothetical satellite is still going to need a chemical rocket, even if you did use a magnetic launch system. It is possible to launch an object with a single impulse into an escape trajectory, but the velocity necessary to do this means that you would have problems with frictional heating with the atmosphere (i.e. the object burning up on the way up). ---
**Author:** ![Quercus](https://avatars.discourse-cdn.com/v4/letter/q/7ab992/32.png) [@Quercus](https://boards.straightdope.com/u/Quercus)\ **Post date:** [January 28, 2009, 7:24pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412/11 "2009-01-28T19:24:59Z")
> [@Frodo](#): > > Why is a railgun needed?, wouldnt the crude device I mentioned work better?, I guess there is a limit to the force you can give to a magnet that prevents doing it?. The force of magnets gets smaller as you get farther away. So if you’re just using one magnet to push and one magnet on the payload, you’re only pushing for a short distance. Which isn’t much different from just loading the payload into a giant cannon or whatever. First, since you’re only pushing for a short time, you need to push really, really, really hard. Second, the payload is going to be smooshed (just like being shot out of a giant cannon). A railgun is a little different: it’s a whole line of electromagnets, so the payload can be pushed a more gently by each magnet, and still get up more speed. ---
**Author:** ![Frodo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/frodo/32/302_2.png) [@Frodo](https://boards.straightdope.com/u/Frodo)\ **Post date:** [January 28, 2009, 7:30pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412/12 "2009-01-28T19:30:13Z")
> [@Quercus](#): > > The force of magnets gets smaller as you get farther away. So if you’re just using one magnet to push and one magnet on the payload, you’re only pushing for a short distance. > Which isn’t much different from just loading the payload into a giant cannon or whatever. First, since you’re only pushing for a short time, you need to push really, really, really hard. Second, the payload is going to be smooshed (just like being shot out of a giant cannon). > > A railgun is a little different: it’s a whole line of electromagnets, so the payload can be pushed a more gently by each magnet, and still get up more speed. Yes, but the idea wasnt to accelerate it gently, just to give it a brute force kick so big that puts it in orbit in one go. ---
**Author:** ![Frodo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/frodo/32/302_2.png) [@Frodo](https://boards.straightdope.com/u/Frodo)\ **Post date:** [January 28, 2009, 7:31pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412/13 "2009-01-28T19:31:17Z")
> [@robby](#): > > There’s a basic orbital mechanics problem that no has mentioned yet that makes this impossible. > > You cannot launch an object into a sustainable orbit with a single impulse (as opposed to a continuous acceleration, like that supplied by a rocket), unless the object is already at orbital altitude. > > The reason for this is that a single impulse (like a shell launched from a cannon), can, at best, only put an object into an orbit that intersects the launch point. So any object launched from a given point on the surface of the Earth is either going to hit the surface of the Earth at some other point, or at best, is going to make one orbit that terminates at the launch point. > > So your hypothetical satellite is still going to need a chemical rocket, even if you did use a magnetic launch system. > > It is possible to launch an object with a single impulse into an escape trajectory, but the velocity necessary to do this means that you would have problems with frictional heating with the atmosphere (i.e. the object burning up on the way up). Ouch, so no go then, perhaps using the magnet as a “first stage”? ---
**Author:** ![Santo\_Rugger](https://avatars.discourse-cdn.com/v4/letter/s/e95f7d/32.png) [@Santo\_Rugger](https://boards.straightdope.com/u/Santo_Rugger)\ **Post date:** [January 28, 2009, 8:23pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412/14 "2009-01-28T20:23:07Z")
> [@Frodo](#): > > Ouch, so no go then, perhaps using the magnet as a “first stage”? What would be the advantage? I think you’re underestimating the constant\* force of gravity while overestimating the impulse strength a magnet can provide. \*Constant as in “always present from launch to orbit”, not as in a constant value. ---
**Author:** ![Cervaise](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cervaise/32/16693_2.png) [@Cervaise](https://boards.straightdope.com/u/Cervaise)\ **Post date:** [January 28, 2009, 8:26pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412/15 "2009-01-28T20:26:37Z")
Sure, this could work. You set up a platform with a matrix of powerful magnets, aligned slightly to create a focal point, such that another magnet would be repelled upward from that point. Then you attach a bunch of rockets to the platform… 😛 ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 28, 2009, 9:12pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412/16 "2009-01-28T21:12:59Z")
Just as a nitpick, this isn’t a rail gun, but a coil gun. In a rail gun, your projectile is always in contact with two rails, through which you run a current through the projectile, with a magnetic field perpendicular to the direction of current and the direction of motion. ---
**Author:** ![Der\_Trihs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/der_trihs/32/233_2.png) [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)\ **Post date:** [January 28, 2009, 10:11pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412/17 "2009-01-28T22:11:37Z")
[Here’s](http://www.newscientist.com/article/dn10180) a proposal for a magnetic launcher. > [@](#): > > Anything launched in this way would have to be able to survive enormous accelerations - more than 2000 times the acceleration due to gravity (2000g). This would seem to be an obstacle for launching things like communications satellites, but Fiske points out that the US military uses electronics in laser-guided artillery, which survive being fired out of guns at up to 20,000g. > > Long-range weapons > The US air force’s interest stems from the ring’s potential to launch small, 10-kilogram satellites into orbit, though the team says it has not been told what kind of satellites these are. Aeronautics researcher Alan Epstein at MIT in Cambridge, US, who is not on the team, says the ring could potentially be used as a weapon. > > Aside from microsatellites, the launch ring would be ideal for delivering supplies to support human spaceflight, such as food and water, which are not sensitive to such high accelerations, Fiske says. “Nearly all of this materiel could be shipped via launch rings, resulting in major reductions in the cost of manned space activities,” he told New Scientist. > > Such a launch ring is technologically possible, but getting the projectile safely through the atmosphere would be challenging, says Epstein. Also, it’s not quite the same, but I recall a proposal for using a large, lightweight superconducting cable ring to levitate cargo off the planet. If possible at all it would only work at the poles, though, since that’s where the Earth’s magnetic field lines go up. ---
**Author:** ![Saltire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saltire/32/553_2.png) [@Saltire](https://boards.straightdope.com/u/Saltire)\ **Post date:** [January 28, 2009, 10:34pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412/18 "2009-01-28T22:34:03Z")
These things are often known in futurism and science fiction as “mass drivers.” One way around the problem that a single inpulse can’t put something into orbit is not to attempt to put the payload in orbit. Throw it into space and catch it on the first pass somehow. You’d want a truly reliable retrieval system, plus some sort of self-destruct device in case of a loose projectile. A common use these are put to in speculation is to send the output of mines and factories on the Moon to a Lagrange point. The ‘bucket’ is magnetically kicked away from the lunar surface with a good deal more force than needed for lunar orbit, because the target is a point in space closer to Earth than to the Moon. The lovely elements of the Moon’s crust are then cheaply available to build stuff in space, which can then be put into other orbits or could then travel about the solar system. ---
**Author:** ![Peter\_Morris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peter_morris/32/359_2.png) [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)\ **Post date:** [January 28, 2009, 10:56pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412/19 "2009-01-28T22:56:03Z")
> [@BrotherCadfael](#): > > Check out the magnetic catapult in Heinlein’s _The Moon is a Harsh Mistress_, for the classic science fiction treatment of this idea. > > Although, as **beowulff** said, don’t hold your breath. Actually, Cyrano De Bergerac was possibly the first to suggest using magnets to fly to the moon. (He was joking, he knew how absurd the suggestion is) ![](https://img.youtube.com/vi/q3PP6ZVe66c/maxresdefault.jpg)https://www.youtube.com/embed/q3PP6ZVe66c?feature=oembed&wmode=opaque ---
**Author:** ![Inigo\_Montoya](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/inigo_montoya/32/124_2.png) [@Inigo\_Montoya](https://boards.straightdope.com/u/Inigo_Montoya)\ **Post date:** [January 28, 2009, 11:10pm UTC](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412/20 "2009-01-28T23:10:32Z")
Why would massive accellerations have to be damaging to electronics? What if you were to pack a component in non-conducting, non-compressible liquid, freeze it and then launch it with the magnets as a first stage and then have a rocket 2nd stage perfect the orbit. The liquid then melts/evaporates away. And (hijack) whatever happened to the cable-system to heaven wherein cables are anchored to the earth and extend well into space? Centrifugal force keeps the cables rigidly erect (heh) and you get stuff into space via elevator. [Next page](https://boards.straightdope.com/t/couldnt-a-magnet-be-used-to-throw-objects-into-orbit/483412.md?page=2)