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Magnetic Ring Could Launch Satellites, Weapons

Posted by ryuzaki0 on from the round-and-round-it-goes dept.

MattSparkes writes, "A new study funded by the US Air Force has suggested a cheaper method of sending satellites (possibly missile weapons) into orbit. A 2-km-wide ring of superconducting magnets would contain and propel a payload, accelerating it over a period of hours, before suddenly flinging the satellite into space at 23 times the speed of sound. The satellites would be engineered to withstand the g-forces encountered (2,000 g), and be cased in an aerodynamic shell. A two-year study has been commisioned and will begin within a few weeks at LaunchPoint Technologies in Goleta, California." New Scientist points out that if such a launch ring were built, it would instantly become "one of the most important targets on the planet."

5 of 612 comments (clear)

  1. Re:Lost in space by megaditto · · Score: 5, Informative

    You are confusing pressure with acceleration. These are not the same.

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  2. a_c = - \omega^2 r by Kadin2048 · · Score: 5, Informative

    Except that the proposed design accelerates the payload around in a circle -- using magnets arranged inside a torus -- not a long straight runway. I doubt a linear runway would be practical; it would just be too long. The advantage of a torus is you can keep using the same magnets to accelerate the payload, over and over, until you've reached sufficient speed to let it fly.

    Unless the circle was ridiculously large (probably the size of a continent or better), you're not going to be able to get up to escape velocity before you'd (as a human being) would be crushed by the effects of the centripetal acceleration.

    I'm not going to do the math right now, but I'm pretty confident that of the 6,000 Gs they're quoting, most of them are in the radial direction and not in the tangential, so that even if you brought the payload up to speed slowly, you'd still be crushed. It would be just like being in a centrifuge.

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  3. Bad math? by Bender0x7D1 · · Score: 5, Informative

    Am I crazy, or did they get the math wrong in the article?

    The acceleration equation for circular motion is: a = v^2 / r

    We are given:

    Velocity: 10 kilometers/s

    Width of ring = 2 kilometers, so radius = 1 kilometer

    So:
    v = 10,000 m/s
    r = 1,000 m

    a = (10,000 m/s * 10,000 m/s) / (1,000 meters) = 100,000 m/s^2

    The acceleration due to gravity is about 10 m/s^2

    This gives: (100,000 m/s^2) / (10 m/s^2) = 10,000 g

    So it seems that their 2,000 g is way off. Even if we use 2 km for the radius it is still 5,000 g.

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    1. Re:Bad math? by doctor_nation · · Score: 5, Informative

      Your math is correct. I have an abstract from a presentation these guys gave last week and it lists the radial force at 20 MN (that's mega-Newtons) for a 200 kg projectile = 10,000 G. They don't list the acceleration in G anywhere so it's probably a New Scientist math error.

  4. Re:Sounds Good, except by NoData · · Score: 5, Informative
    I know there's a relationship between bird migration and magnetic fields, too, as a lot of them blindly smack into the brick walls at a local MRI center.


    Cute, but you gotta be kidding. I work with a 3T research MRI magnetic. Both the machine and the facility are heavily shielded, and the field drop-off is very steep. While the isocenter of the bore is at 3 Tesla (30,000 Gauss), the 5 Gauss line is only a few meters (about 5 in the axial direction, 3 in the radial direction) from the isocenter. By comparison, a kitchen magnet is maybe 100-250 Gauss.