A circular railgun in space to propel objects to other solar systems?

Discussion in 'Astronomy, Exobiology, & Cosmology' started by s0meguy, May 29, 2011.

  1. Eagle9 Registered Senior Member

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    billvon
    If we do like this then the spacecraft will have to spend millions of years to reach the nearest stars

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    And do you think that the rope can work as railgun?

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  3. phlogistician Banned Banned

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    Oh dear. That final velocity is just not achievable, is it? And, you forgot to factor in the Lorentz transformation, because approaching 2/3c, relativistic effects are significant.
     
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  5. billvon Valued Senior Member

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    Then just make the rope longer. Or start an engine after you release from the rope. (You'll need one anyway to slow down at the other end.)

    More like a slingshot - but same idea.
     
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  7. phlogistician Banned Banned

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    Nah, no retro rocket required, given the projectile won't survive the initial acceleration phase anyway. One speck of dust, and the kinetic energy in that collision will destroy it.
     
  8. billvon Valued Senior Member

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    Eh, put an ablative barrier on it, along with a magnetic field to deflect the charged particles and you'd survive a pretty long flight.
     
  9. phlogistician Banned Banned

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    Then it will be the ablative barrier that blows everything to smithereens. It doesn't matter what that particle hits, it's the the kinetic energy of objects colliding at 2/3c you have to worry about.

    Magnetic field to deflect charged particles? Since when was dust charged? So you are going to try to ionise and deflect particles at 2/3c? Any idea what sort if impulse you are going to need to give them to get them out of the way? Do the maths please, and factor that into keeping the vehicle running straight on it's accelerator, because if you push a particle out of the way real quick, that force has an equal and opposite reaction moving your vehicle.
     
  10. Eagle9 Registered Senior Member

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  11. billvon Valued Senior Member

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    Yeah, that's how it works. It's a series of very fine, very thin membranes hundreds of miles in front of the vehicle. Any small collision turns into energy and you get a big explosion - miles from the vehicle. Once you lose enough of them you deploy new ones.

    Most of the stuff you will run into in interstellar space isn't "dust" per se - it's molecular in sized, and in denser areas, is generally ionized (which means it has a charge.) For example, the solar wind is primarily hydrogen nuclei and electrons, both of which are easily deflected by a magnetic field.

    Particles larger than a few hundred atoms generally won't have a significant net charge, and have to be stopped by mechanical barriers (like the membranes mentioned above.) Fortunately they are in the very small minority.

    Not much. Keep in mind that if you are trying to clear a space for, say, a 20 foot diameter vehicle, and your fields extend out 200 miles in front of you, you only have to deflect the path of the particle (as seen from the vehicle's perspective) by .001 degrees over the course of about a millisecond. That's not much, especially for nuclear-sized particles. Magnetic fields in particle accelerators do far more deflection in far shorter periods of time.

    Oh, that's definitely true - and you will be expending a lot of power/reaction mass to maintain your speed against the drag caused by the interstellar medium. Interstellar travel is not easy.
     
  12. NMSquirrel OCD ADHD THC IMO UR12 Valued Senior Member

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    lol..the space elevator got a little out of control..next stop orion nebula..prepare for emergency landing..

    i had other questions but couldn't figure out how to ask them..
     
  13. phlogistician Banned Banned

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    Hundreds of miles? Got a practical solution, rather than this purely hypothetical one?


    We aren't talking about attempting 2/3c inside a solar system though are we? Only beyond the heliopause, 'cos inside a solar system would certainly involve a collision with a large enough particle to ruin your day.

    Yeah, rare, but then space is very, very big. Travelling a few light years, you only need one speck.


    200miles? Again, do you have a practical, and not hypothetical solution for generating such a HUGE magnetic field?

    Not from 200miles away. What's the diameter of the LHC? A few metres, that's the distance from which particles are deflected. Add an inverse square law and we are talking humongous amounts of power.
     
  14. MicroCubedX3 Registered Member

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    Other then molecular particles within the heliosphere most micro meteors are iron so magnetized shielding should push them out of the way.
     
  15. wlminex Banned Banned

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    . . . .h-m-m-m-m . . .perhaps the railgun track would effectively be shorter from an outside (railgun) observer POV . . . due to LF contraction as the payload velocity approached c? Once attaining near-c, railgun length would 'shorten'? . . . I'm not sure how LF contraction would would work in a curved path configuration, however. Also . . . have to consider all that additional mass gained by acceleration. Might be kinda like the trip Jodie Foster took in "CONTACT"?

    wlminex
     
    Last edited: Aug 12, 2011
  16. billvon Valued Senior Member

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    It is entirely practical, one currently being used on the space station. Due to the vastly lower speeds involved they just use fabrics that are separated from the hull by a few inches; high energy impacts vaporize the external fabric and dissipate by the time they reach the pressure hull. Works well, although from reports by astronauts larger impacts make quite a racket.

    The original poster was, yes.

    It takes a lot of power to establish a strong magnetic field but it takes zero power to maintain one.
     
  17. origin Heading towards oblivion Valued Senior Member

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    The rail gun does not move so it would not have any length contraction. The projectile would be the object that the outside observer would see as length contracted.

    Regardless as mentioned earlier in the thread to reach relativistic speeds it would still take an absurdly huge diameter and an ungodly amount of power.
     
    Last edited: Aug 12, 2011
  18. wlminex Banned Banned

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    Origlm: "Agreed!"

    wlminex
     
    Last edited: Aug 12, 2011

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