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This sounds so cool, though I know nothing about it. I want to drive an asteroid. [+] |
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It's also possible that we can't. |
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Presumably easy-peasey to find out which, by building a big solar-powered-electro-magnet in space, and see what sticks |
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Some asteroids are already magnetic. |
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If the orbital dynamics are chaotic, then arbitrarily small
magnetic
perturbations should suffice to save the earth. Problem is,
it may require arbitrarily large computers. |
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// If the orbital dynamics are chaotic, then arbitrarily small magnetic perturbations should suffice to save the earth.// |
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Or destroy it. That's the problem with chaos, it's unpredictable. |
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Are you sure? My understanding was that a chaotic
system's only unpredictable in principle if you try to
predict for all future time. Since states diverge
exponentially, if you're predicting a finite time into the
future, there is, for any desired prediction accuracy, a
finite accuracy (for measurement and computation) which
suffices to achieve it. Of course, that accuracy will, in
general, not be practically achievable (hence the crack
about arbitrarily large computers). |
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Also, there are control systems for some chaotic systems
that don't rely on actually solving the system. |
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The point is, if an arbitrarily small perturbation would suffice to save the earth, then an similarly small perturbation could make it hit the earth. Perturbations such as a knot in the solar wind, a solar flare, or a micrometeorite strike. These can't be calculated, no matter how much computing power you have. |
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[ldischler] //Some asteroids are already magnetic.// |
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Well, that's easy then! Simply reverse the Earth's magnetic field and repell them! |
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Since a magnetic field can only impart a turning moment to the asteroid no change in orbit can be expected from changing its magnetisation. |
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Since magnets are bipolar, any turning motion, or other perturbations would only increase the chances of bringing the asteroid down towards one of the poles. Perhaps slightly preferable to an equatorial crash, but still pretty bad. |
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//Since a magnetic field can only impart a turning moment// |
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//Physics double-take moment// |
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A uniform magnetic field, that is, which it will be if we are considering the magnetic field of the earth out at the distance of a typical asteroid orbit. |
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Space: the final affront here. |
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I love the optimistic brevity of this idea. |
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