The DARPA 100 Year Starship

Discussion in 'Science and Technology' started by John O., Jun 18, 2011.

  1. MANT!

    MANT! Rear Admiral Rear Admiral

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    I do like the *First one needs to have a destination* aspect of the project..
    once the destination is found, the political and financial backing would be easier.

    Also taking the long term approach is far better than any "Get There Now" as total costs (though high) would be spread out over a much longer period of time, making budgeting much easier.

    the matter of interstellar flight can take several tacks.. a new propellant source or crude use of power..

    http://en.wikipedia.org/wiki/Project_Daedalus
    http://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)

    http://en.wikipedia.org/wiki/Project_Longshot

    as designs already exist for crude interstellar spacecraft, it only makes sense that a destination needs to be found first...
     
  2. John O.

    John O. Rear Admiral Rear Admiral

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    I agree, another aspect this symposium will certainly have to tackle is that we can't just rely on ideas that may be technologically sound but pragmagically inviable. A pulsed nuclear propulsion system would require too many nuclear detonations to ever work, unfortunately, unless somehow the political climate about it were to change drastically or some powerful and influential politician were to get it into his head to make it possible..
     
  3. sojourner

    sojourner Admiral Admiral

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    Pulse nuclear will never be politically viable near earth. Once we branch out into the solar system though, it may catch on.
     
  4. John O.

    John O. Rear Admiral Rear Admiral

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    Yeah but we would have to be so branched out that even testing could be done at a safe distance, if the political environment about nuclear detonations remains the way it is.

    Actually I think the idea of even building warheads again, for any purpose, would be difficult to sell, in part because it involves rebuilding a lot of government infrastructure associated with nuclear arms construction and there'd be a hoopla over that.
     
  5. sojourner

    sojourner Admiral Admiral

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    ^well, I could see a scenario where the warheads are built off earth. I don't think nuclear pulse will ever be allowed near earth. period.
     
  6. Yminale

    Yminale Rear Admiral Rear Admiral

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    Uhm you do all know that this is a PR (and possible recruitment) even. DARPA is not serious about building a starship (America probably won't be around in a 100 years)
     
  7. sojourner

    sojourner Admiral Admiral

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    ^Nope, didn't know that at all..

     
  8. STR

    STR Captain Captain

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    As far as I'm aware, they never really disassembled much of the warhead building infrastructure. You actually need a fair amount of infrastructure to maintain and refurbish existing warheads. In fact, it appears that they've recently begun replacing older structures with new ones, like the "Kansas City Plant" which makes electronic and mechanical components for warheads.
     
  9. STR

    STR Captain Captain

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    Thanks! I was a bit confused until I realized you were talking about a Polywell. Interesting stuff. Do you need a self-sustaining fusion reaction to make this a viable space motor?
     
  10. John O.

    John O. Rear Admiral Rear Admiral

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    Cool, I didn't know that. That's encouraging, actually.

    I was actually thinking about also presenting on antimatter catalyzed thermonuclear pulsed propulsion on my own, I did some research on that a few years ago as well, but I doubted its political viability.


    We don't think so, no. Right now the math tells us that if the ions are coming out in a beam they will be highly energetic, enough to make it an extremely lucrative electric thruster to fill the gap between high-Isp Hall Thrusters and high thrust rocket motors. The "make or break" engineering problem right now is making sure it's in fact a neutral ion beam and not an electron beam. Electron beam = no appreciable thrust whatsoever (plus charge disparity issues). It may take some tweaking of the IEC to ensure it's a neutral ion beam.
     
  11. STR

    STR Captain Captain

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    Thanks, just a couple more Q's. Really interesting stuff, though the engineering is beyond this MBA student.

    Would you even be able to use the IEC as a fusion reactor while it's being used as a motor?

    Also, regardless of power source, how many kW of power would you need to sustain the thing? I know enough that RF is a decently efficient way to heat things up, but I have no clue what it takes to get plasma temperatures.
     
  12. Ronald Held

    Ronald Held Rear Admiral Rear Admiral

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    Our government cannot have steady spending for more than a few years, so 100 year plans will not work until the US( and world )can engage in long term projects.
     
  13. sojourner

    sojourner Admiral Admiral

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    ^Which is the whole point of the project. It's not "how to build a ship", it's "how to build a sustainable program on a long term basis".
     
  14. John O.

    John O. Rear Admiral Rear Admiral

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    Exactly, I think it's a foregone conclusion that one of the goals of this symposium and future movements are to figure out how to make it self sustaining (think Men in Black funding itself through space technology patents, lol)


    1st Q - there's plenty of varying opinions on that. Some would argue quite ardently that in 30 years of trying, the IEC has not shown itself to be a promising potential environment for any significant amount of fusion to take place. Others disagree. I think the central point is that even if it never does, and the IEC functions as nothing more than an ion accelerator - in a sense, you could think of it as an electrostatic nozzle (versus the VASIMIR's magnetic nozzle), it still represents the potential for a very useful thruster compared to modern electric thrusters that are out there (Hall, Ion).

    2nd Q - it's not so much an issue of needing a lot of power to sustain the engine - what you're talking about when ur talking about sustaining the engine is in fact just making sure the helicon ignites a plasma and the IEC fires too, which has more to do with striking the right pressure / gas flow rate balance. There are minimum values the voltage on the IEC grid to get ignition, and RF power to get a plasma, but they're low.

    In other words, the engine doesn't have exceptionally high power requirements for missions like satellites - but if you wanted a big ole engine to get u to Mars, you are probably talking about needing anywhere from 2 kilowatts to... whatever you could generate. I mean as far as we can tell, it continues to scale upward without loss of efficiency in terms of power. I mean the point of increasing RF power is to get a higher plasma density (higher ionization fraction), but by the helicon's very nature it actually produces a very high ionization fraction (like .9) - hence recent (last 2 years) widespread interest in it as an ion source for propulsion systems, because that's much higher than previous ion production methods. In case it's not immediately clear, higher plasma density is desirable because in the IEC environment, only charged particles (ions) do you any good; neutral particles are useless. In academic discussions of modern electric thrusters this is not always made clear, but one of the major failings of electric propulsion systems to date has been a lack of an ability to generate a high ionization fraction, and the corresponding efficiency loss is termed "propellant utilization efficiency" which is often no higher than .6 or .7 in ion and hall thrusters, because the process of ionization is in fact, a somewhat difficult and high-energy process (conventionally). That's what's so cool about the helicon.

    Now, power in space is potentially hard to come by, but solar arrays are really taking monumental steps forward. I did a really large photovoltaic report recently (some may remember I asked for PV specs on Juno and Phoenix) and Dawn produced about 2.5 kW for its ion engine; Juno's array will produce (launches in August 2011) about 15 kW in LEO and ~500 W at Jupiter. That is really pretty remarkable, and it's not simply a giant array - it's large but it also represents a couple of fundamental leaps forward for PV technology. It's kind of a rare island of prosperity in the space industry in that there are 2 high dollar sources of funding for PV use - both the growing international and domestic interest in clean energy technology (which is gradual but ever present), and secondly and probably a more significant short term boon for the tech, is the fact that every single satellite going up today - whether it's for telecom, military, academic, whatever - has to rely on solar for power, so there's a tremendous interest in the private sector to reduce costs and improve efficiencies. Lot of money going into it, which is going to help make some of these next-gen electric propulsion systems become more viable.
     
  15. RAMA

    RAMA Admiral Admiral

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    Doesn't matter, its going to take 100 years of organizing, planning, testing and building to get such a starship going. Our problem on Earth is usually short-sightedness, the fact that there is even money involved now is a good sign to me.

    RAMA
     
  16. RAMA

    RAMA Admiral Admiral

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    :lol: Why? The US is is more stable than any nation on the planet. Its the most adaptable, diverse....these are good qualities to have, and ones that many supposed "empires" that did not last didn't have. Even if the world is more united in 100 years, I'd expect the US to be a strong component. The strange idea some people have that the US is at the end of its infleunce is one of the most ludicrous I've seen, and very likely just wishful thinking ifrom certain parts of the world.

    RAMA
     
  17. sojourner

    sojourner Admiral Admiral

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    What "doesn't matter"? Did you respond to the wrong person here? Because you seem to be agreeing with my post. DARPA realizes it will take 100 years. That's what this study is about. Developing an organization that can last that long to achieve it's goal.
     
  18. RAMA

    RAMA Admiral Admiral

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    It doesn't matter they're not actually building the ship, as many people are reading into this. Yes we are agreeing...
     
  19. MANT!

    MANT! Rear Admiral Rear Admiral

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    You sound like Al Qaeda's wishful thinking..
     
  20. John O.

    John O. Rear Admiral Rear Admiral

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    pft. If we're not around it won't have anything to do with al qaeda. Our social infrastructure is more fragile than people think. Stop paying cops & emergency services workers and see what happens.