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VASIMR Propulsion

  1. Jul 28, 2007 #1

    Astronuc

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    Evo brought this to my attention in another thread.

    http://www.adastrarocket.com/home.html

    http://www.adastrarocket.com/vasimr.html
    This is basically a plasma device, but there is not thermonuclear reactions. The gas propellant is simply heated by RF heating and passed through a magnetic nozzle.

    Cheers, Evo!
     
  2. jcsd
  3. Jul 28, 2007 #2

    Janus

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    A couple of years ago, we had a little project here at PF where we planned a sample return mission to Europa. The VASIMR was our propulsion system of choice.
     
  4. Jul 29, 2007 #3

    Astronuc

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    VASIMR is attractive, but the last I heard about 2 yrs ago was that there was no thrust, or rather insubstantial thrust.

    So the technical challenges have been thrust and duration.

    With very high Isp, VASIMR would be fine for a small spacecraft, e.g. on the order of 1 MT (1000 kg), and hopefully the thrust would be something like 10-100 N. Even then the acceleration is very low, but it's continuous.

    Basically, the force has to exceed the force imposed by the local gravitational field, otherwise the craft is not going anywhere.

    Then there is the matter of duration. About 20+ years ago, the benchmark was 7 yrs or ~61,000 hrs (219,600,000 s) of continous operation. The challenge for many plasma and electrodynamic systems is the erosion of components at temperature, and rates of nm/s add up.
     
  5. Aug 11, 2007 #4

    So you're saying that under ideal conditions, a 1000-kg VASIMR rocket could launch from earth to orbit? How slow would its acceleration be in Earth's gravity? How long would it take to reach orbit?
     
  6. Aug 11, 2007 #5

    Danger

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    No way could one of those launch from Earth. It would have to be either assembled in orbit or lifted to orbit by a chemical rocket. It would be the same idea as an ion thruster—small impetus over an extended period of time.
     
  7. Aug 11, 2007 #6

    Astronuc

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    VASIMR is low thrust, high Isp, so as Danger mentioned, it won't get from earth's surface to orbit. VASIMR would be applied to a craft already in orbit, whether launched whole from the surface or assembled wholly or partially in orbit.
     
  8. Aug 12, 2007 #7
    So then what is the solution for very heavy launch payload to orbit, like on the or of a thousand tonnes or more?
     
  9. Aug 12, 2007 #8

    Astronuc

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  10. Aug 12, 2007 #9
    There are no fundumental problems with VASIMR. The main problem is simply power. For example, just the 10 N thrust version with an Isp as low as 1,000 seconds would require over 50 KW, which is something above 11,000 square feet of solar panels. At this point, unless a nuclear reactor is used, the advantages of using such a system on a large spacecraft are negligible if any.
     
  11. Aug 12, 2007 #10
    Naturally, I was only considering VASIMR in conjunction with a nuclear power source, as any other power source would be impractical.
     
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