# Can we use magnets to draw meteors and asteroids away from earth?

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#### mydogdottie

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I was watching a show the other day that discussed the feasability of shooting an asteroid with a nuclear weapon to deter it from impacting earth. So that got me thinking of different ways to impact asteroids. Is it possible to draw it out of its collision course with earth by the use of high powered magnets?

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#### DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I was watching a show the other day that discussed the feasability of shooting an asteroid with a nuclear weapon to deter it from impacting earth. So that got me thinking of different ways to impact asteroids. Is it possible to draw it out of its collision course with earth by the use of high powered magnets? <br />Posted by mydogdottie</DIV></p><p>Many asteroids have a high iron content and so might respond to a magnetic field.&nbsp; However, it would take an enormous magnetic field to have much effect from&nbsp;a distance.&nbsp; More importantly, you are still stuck with conservatioin of momentum and that force would have to emanate from a very large body to effectively deflect the asteroid.&nbsp; That large body would have to be in space somewhere -- if the magnet were based on Earth it would tend to create collisions rather than avoid them.&nbsp; Basically you are using the momentum of the magnet and whatever it is attached to, to couple with the momentum of the asteroid and provide a velocity vector that avoids a collision.&nbsp; Whatever means you use to give the magnet sufficient momentum might be more easily used to alter the momentum of the asteroid directly.&nbsp; What a nuclear explosion might do is to split the asteroid into parts, with individual velocities that result in no collision.&nbsp; But the momentum of the total system remains unchanged.&nbsp; Ditto with your magnet idea, but now the magnet is part of the system.</p><p>Now if the asteroid had a net electric charge that might, in principle, change things a bit, but you would still need an enormous magnetic field, and if it were based on Earth, your hard disc might have a problem or two.&nbsp; And a significant charge, for these purposes, on the asteroid is not likely.</p> <div class="Discussion_UserSignature"> </div>

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#### MeteorWayne

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<p>ANother thing to consider; one theoritcal plan to deflect asteroids away from an earth intersection is to use the gravity of a nearby spacecraft to move it (really, just shift it's velocity a tiny bit, which is all you really need to avoid an impact. It can still cross the earth's orbit, you don't have to change the position of the orbit much; just ensure that earth isn't there when the asteroid crosses our orbit).</p><p>I'm not sure whether gravtity of magnetism would be more efficient; I'll have to grapple with that for a bit. Any ideas Dr Rocket?</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

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#### DrRocket

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>ANother thing to consider; one theoritcal plan to deflect asteroids away from an earth intersection is to use the gravity of a nearby spacecraft to move it (really, just shift it's velocity a tiny bit, which is all you really need to avoid an impact. It can still cross the earth's orbit, you don't have to change the position of the orbit much; just ensure that earth isn't there when the asteroid crosses our orbit).I'm not sure whether gravtity of magnetism would be more efficient; I'll have to grapple with that for a bit. Any ideas Dr Rocket? <br />Posted by MeteorWayne</DIV></p><p>Kinda depends on what the asteroid is made of.&nbsp; You can certainly make an electromagnet that would apply more force to an iron asteroid than would gravity of anything like a spacecraft.&nbsp; After all they lift cars with magnets.&nbsp; But all that is doing is providing a means for coupling the momentum of the spacecraft to the momentum of the asteroid -- and this applies to the gravity notion also.</p><p>To really talk intelligently about this you need more specifics as to the orbit of the asteroid and where&nbsp;in that orbit you apply the perturbation.&nbsp; A little perturbation can go a long way, but only if you have a lot of time to realize the effect.&nbsp; I think the real issue is not how to apply the perturbatin so much as identifying the problem with sufficient lead time to be able to take action, and being able to take action far enough away from Earth for the action that is possible to be effective.<br /></p> <div class="Discussion_UserSignature"> </div>

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#### MeteorWayne

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<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>&nbsp; A little perturbation can go a long way, but only if you have a lot of time to realize the effect.&nbsp; I think the real issue is not how to apply the perturbatin so much as identifying the problem with sufficient lead time to be able to take action, and being able to take action far enough away from Earth for the action that is possible to be effective. <br />Posted by DrRocket</DIV><br /><br />We certainly agree on that. I'm rather encouraged by the recent NEO searches. They appear to be having great success, even identifying very small asteroids if they come close enough. Of course, if a previously undecteted one is&nbsp;found with our name on it (more likeley a comet or degassed comet nucleus with high eccentricity, and enough inclination to be out of the plane of the solar system) we would have no time to react.</p><p>These low acceleration methods only apply to short period asteroids that repeatedly pass us. That gives us time to be aware of the problem, formulate plans, and have somebody get off their ass and actually plan and pay for a mission. It's a good thing that, so far, we have plenty of time....</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

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