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NASA Plans Test of New Plasma Drive 266

Posted by timothy
from the please-don't-bring-carrie-ann-moss dept.
Sallust writes "Flightglobal has an interesting article about the testing of a new electrically powered plasma engine called the Vasimir. It's being developed by former astronaut Franklin Chang-Diaz and promises to greatly reduce the time and fuel required for interplanetary journeys. According to the article: 'The Vasimir involves the injection of a gas such as hydrogen into an engine that turns it into a plasma. That plasma is then energised further using radio signals as it flows through the engine, a process controlled by electromagnetic waves from superconducting magnets. Accelerated and heated through this process the plasma is focused and directed as exhaust by a magnetic nozzle. Vasimir is many times more efficient than conventional chemical rockets and far less fuel is needed.' The developers are finalising an agreement with NASA to fit a scaled-down version of the engine to the ISS to conduct operational tests. There is also a concept video on YouTube suggesting a journey time for a manned craft to Mars on the order of 60-70 days."
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NASA Plans Test of New Plasma Drive

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  • by BigDaddyOttawa (948206) on Wednesday August 06, 2008 @02:45PM (#24500771) Homepage
    What could possibly go wrong?
    • by oldspewey (1303305) on Wednesday August 06, 2008 @02:49PM (#24500827)
      It's okay as long as they remember to leave the parking brake on.
    • by freddy_dreddy (1321567) on Wednesday August 06, 2008 @03:11PM (#24501155)
      I think the point here is to exploit the recent discovery of water on Mars. With conventional fuels you have to take the return-charge with you. Concepts like these allow them to harvest Hydrogen on Mars for the return trip, which is pretty useful. The painful detail (apart from the complexity) is the mechanism for braking - you're f*d if that fails.
      • by Amouth (879122) on Wednesday August 06, 2008 @03:31PM (#24501475)

        actualy because this design heats the gas to a plasma state then uses EM waves to move it to create thrust - the idea could be used on just about any gas - your effeciency would be how much energy goes into heating it to a plasma state and keeping it there.

        this is a great idea because they could design one engine and while the gas is consumed it could be replaced by any gas - and electricity is the true source of the power to run the engine..

        we already know what gasses are readly avaliable on mars - design one to run on say H to get there (assume Hyrdogen is the easiset to heat to plasma sate) but have the engine also able to run on the gasses from Mars.. then when it gets there refill the tanks.. carge up the batteries (or use a nuke power source on the thing) and come on back - or keep going.

        think of a ship with this type of drive.. then think about adding say a Bussard collector http://memory-alpha.org/en/wiki/Bussard_collector [memory-alpha.org] (i know we would have to invent a bussard collector but the idea is not that hard)

        if this works they way the say it does - it is going to be one of the best propultion advances for traversing our solar system.

        and with us having probes leaving our system - the data from there might show that there is a good ammount of particals in the space between systems.. if that is true then you could use this to send probes to other systems. sure it would take awhile but i bet they can alwasy make improvements.

        • by Omega996 (106762) on Wednesday August 06, 2008 @04:07PM (#24502057)
          yeah, designing and building a bussard collector isn't that hard, it just needs something that can generate a magnetic field that doesn't diminish as the inverse square of the distance, since your magnetic or electrostatic funnel would have to be huge to pull in enough material to be worthwhile (even inside the heliopause). unless you're planning on not using a vehicle with any live crew or any sort of electronic equipment. I'm sure the difficulty of initiating and sustaining a proton-proton fusion to generate plasma is just a quick fix (no doubt you've already figured out the materials and fuel source for your carbon-nitrogen-oxygen fusion catalyser), as are the problems associated with getting the ramjet to speeds above the solar wind (unless the vehicle is making a quick one-way trip into the sun).

          not much to do there, at all. You should get right on it, and we'll be heading toward Mt. Lookitthat within a few months. *rolleyes*
        • Re: (Score:3, Interesting)

          by nacnud75 (963443)
          The Environmental Control and Life Support System (ECLSS) planned for the ISS will use recycled water and split it into Oxygen and Hydrogen. The Oxygen is used to support the crew while the hydrogen is dumped. A VASIMR might be able to use this hydrogen to reboost the station, reducing the need for ISS resupply with toxic propellants.
    • Sounds like a great idea given their success with other [slashdot.org] experimental electrically based thrusters

      tm

  • Makes me happy (Score:4, Insightful)

    by SSIlver2002 (1287620) on Wednesday August 06, 2008 @02:46PM (#24500785)
    It's stuff like this that makes me happy and brings a huge smile to my face. It also makes my imagination go wild! I hope something like this gets implemented sooner than later.
  • by oldspewey (1303305) on Wednesday August 06, 2008 @02:48PM (#24500801)
    Neither summary nor TFA give any indication of the velocity of plasma exiting the engine. How does it compare with chemical rocket? Ion drive?
    • by Intron (870560) on Wednesday August 06, 2008 @02:53PM (#24500887)
      We can guess that it is similar to the DS-1 Ion drive [nasa.gov] which propels Xenon ions at 30 km/sec.
      • by avandesande (143899) on Wednesday August 06, 2008 @03:15PM (#24501225) Journal

        From wiki:

        Current VASIMR designs should be capable of producing specific impulses ranging from 3,000 to 30,000 seconds (jet velocities 30 to 300 km/s). The low end of this range is comparable to some ion thruster designs. By adjusting the manner of plasma production and plasma heating, a VASIMR can control the specific impulse and thrust. VASIMR is also capable of processing much higher power levels (megawatts) than existing ion thruster electric propulsion designs. Therefore it can provide orders of magnitude higher thrust, provided a suitable power source can be provided.

    • by wurp (51446) on Wednesday August 06, 2008 @02:53PM (#24500893) Homepage

      This sounds a lot to me like it *is* an ion drive. I didn't RTFA, but a plasma is characterized by a separation of the electrons from the nuclei. The only difference between that and an ion drive is that not necessarily all electrons are stripped from the atom in an ion drive.

      I don't know how (or if) you would distinguish between ionic hydrogen and a hydrogen plasma (hydrogen atoms have only one electron...)

      In both cases you give the propellant momentum with either electric or electromagnetic force, and both are much more efficient than chemical rockets. I would also expect both to have miniscule thrust compared to chemical rockets, and hence only be appropriate for navigation when you already have orbital or superorbital velocities.

      • by HRogge (973545) on Wednesday August 06, 2008 @03:09PM (#24501111)

        Ion drives use electromagnetic fields to accelerate particles with an accelerator. Most times they use heavy atoms like xenon.

        VASIMIR makes plasma from light elements like hydrogen and then use electromagnetic fields to heat the plasma... by controlling the temperature you can change the thrust/momentum the engine creates.
        (at least that's what I heared).

      • by wurp (51446)

        Well, actually I *do* know the difference between ionized hydrogen and hydrogen plasma - hydrogen plasma may have all the electrons present, they just won't "stick" too the atoms because they're too energetic (i.e. hot).

        By definition, atoms in a plasma have lost their electrons due to temperature.

        I really just wanted to point out that they're very similar. I'm sure HRogge is right regarding the differences.

      • Re: (Score:2, Informative)

        by Anonymous Coward
        The VASIMIR isn't new... it was developed by NASA over 10 years ago, but the power-thrust/mass ratio didn't justify funding it. It just sounds like someone who wouldn't let it die. You're right, this is an ion drive with the difference that the net fuel charge is zero, as opposed to a true ion drive which ionizes a neutral fuel (usually a noble gas like Xe or Ar) and uses the excess charge repulsion to generate thrust. This disassociates neutral hydrogen using RF coils, so no charge is introduced, but th
    • by DarthVain (724186) on Wednesday August 06, 2008 @02:55PM (#24500913)

      More importantly how does it compare to twin ion engines? The empire wants to know!

      QIE - Quad Ion Engines, now with the added benefit that they don't look like bowties. Under utilized as the name isn't very catchy...

    • by bodino (240393) on Wednesday August 06, 2008 @03:00PM (#24500973) Homepage

      Wiki - the source of all knowledge - has some good details.

      http://en.wikipedia.org/wiki/Variable_specific_impulse_magnetoplasma_rocket [wikipedia.org]

    • radio heating scales (up) much more easily than ION thrusters.
      Google 'microwave plasma balls' and you will get the idea.

    • by AKAImBatman (238306) <akaimbatman.gmail@com> on Wednesday August 06, 2008 @03:08PM (#24501093) Homepage Journal

      VASIMR (Variable Specific Impulse Magnetoplasma Rocket) [wikipedia.org] is a variation on the Magnetoplasmadynamic thruster (MPDT) [wikipedia.org] that has been in development for a decade or two. These thrusters are coveted for their rare combination of high specific impulse (i.e. efficiency) and thrust to weight ratio (power). Such a combination makes them ideal for manned missions, as they allow space craft to fly under constant, high powered thrust. This is the "holy grail" of space travel because it cuts down the TIME in flight significantly. Thus the summary's mention of a 90 day flight time to Mars. (Normal flight time using a minimal Hohmann Transfer is ~1.5 years.)

      Obviously, the exact thrust numbers depend upon the rocket. However, the VASIMR rockets have a range of specific impulses from 3,000 to 30,000 seconds. You can see how that compares to Ion Thrusters here [wikipedia.org]. Chemical rockets tend to top out at 500 seconds and thus don't even place when compared to VASIMR or Ion thrusters. The only reason why we want to keep using chemical rockets once we have better thruster technology is that all these new technologies lack the thrust to weight ratio to get a rocket off the ground. i.e. They are only good for space travel. Atmospheric flight need not apply.

      • by rk (6314) * on Wednesday August 06, 2008 @04:25PM (#24502313) Journal

        (Normal flight time using a minimal Hohmann Transfer is ~1.5 years.)

        I think you forgot to divide by two. The duration of the whole Hohmann Earth/Mars transfer orbit is about this long, but you only use half of it to get there.

      • Re: (Score:3, Interesting)

        by mi (197448)

        However, the VASIMR rockets have a range of specific impulses from 3,000 to 30,000 seconds.

        This is the part I don't get, but you probably do. Why would I lower the exhaust speed, instead of lowering the mass?

        The distances a spacecraft can travel in a given time are limited by the mass of "stuff" it can throw back multiplied by the speed, with which it is thrown. So, one would think, the most efficient engine would be throw "stuff" out as fast as it can, and if lower thrust is desired at times, it would th

        • by GleeBot (1301227) on Wednesday August 06, 2008 @10:02PM (#24505571)

          Actually, the main reason to have a variable Isp (specific impulse) engine is because there's a direct trade-off between Isp, and energy.

          Note that momentum transfer increases linearly with velocity and mass, but kinetic energy increases linearly with mass and with the square of velocity. Thus, to make a given amount of mass go faster requires a lot more energy.

          A more concrete example: You want to impart a total impulse of 2MV. You can either get it throwing out a mass M at 2V (mass efficient), or by throwing out a mass 2M at V (energy efficient).

          In the first case, you use 1/2 M (2V)^2 = 1/2 M 4V^2 = 2MV^2 energy, while in the second case, you use 1/2 2M V^2 = MV^2 energy, or half as much, for the same total impulse. This only gets worse the bigger the velocity difference gets.

          Often, the limiting factor in electric propulsion technologies like these is the power supply, not the thruster. Generally, to get the max Isp all the time you'd need a power supply so massive (like a nuclear reactor) as to completely throw off the mass fraction.

          So generally, the way these systems are proposed to be operated is with a fixed power budget, and switched between mass efficient, low thrust mode (for long term delta-V), and mass inefficient, high thrust mode (for certain maneuvers).

    • by jmichaelg (148257)

      The manufacturer has this chart [adastrarocket.com] showing that it's a variable thrust rocket - hence the name: Variable Specific Impulse Magnetoplasma Rocket (Vasimir).

      Unsaid is where the power comes from to drive the rocket. To get the kind of thrust they're looking for, it'll most likely be a descendant of Admiral Rickover's reactors we use in submarines because they're compact power sources.

      Unfortunately, we're talking about NASA which means they're not really planning on doing anything. Per the article, Griffin wouldn't

  • by CRCulver (715279) <crculver@christopherculver.com> on Wednesday August 06, 2008 @02:49PM (#24500823) Homepage
    Who knows if this thing will work out, but it would be amusing if it did. In histrilogy beginning with Red Mars [amazon.com] , Kim Stanley Robinson had interplanetary journeys being trimmed down to such short lengths only a couple of hundred years from now, and KSR's work tried hard to be scientifically plausible.
    • by spun (1352) <loverevolutionary @ y a hoo.com> on Wednesday August 06, 2008 @03:00PM (#24500975) Journal

      Fact is often capable of moving faster than fiction, it just takes a collective decision to make it so. We could have been to Mars already, just like we could be feeding everyone in the world. We just don't care enough.

      • I frequently see in slashdot replies that this or that could happen if enough folks decide to do it. People say things like "feeding the world is a political problem, not a resource problem." The problem is that political will and the ability to manipulate it are kind of like limitations based on laws of physics. Sure in theory we could steer the earth if we all jumped up and down at the right time. It just isn't possible to convince everyone to play.
    • by molo (94384)

      Yeah, but in the series, transport power was based on cheap cold fusion of water. They would accelerate a craft at 1g towards the target, drift for a time in the middle, and then turn around and decelerate at 1g for roughly the same time. It provided transport between Mars and Earth orbits on the scale of a week (depending on their relative positions).

      Then the slow part of the journey was considered to be the time spent ascending and descending the space elevators to reach the planet's surface from orbit.

  • by fiannaFailMan (702447) on Wednesday August 06, 2008 @02:49PM (#24500831) Journal
    ...is optimize the plasma conduits, although they'd better make sure not to divert too much power away from the main deflector array, I'd hate to have to reconfigure that thing yet again.
    • by fm6 (162816)

      It took longer for somebody come up with a Star Trek tie-in than I thought. Are we finally tired of that particular franchise?

      As I recall, the plasma conduits on Star Trek were always blowing up. Very convenient for the writers in case they need to stage a tragic death on the bridge, though it seems strange that they'd route such a dangerous device into an area populated by so many key people. In any case, plasma is obviously dangerous and unreliable, and I wonder at NASA using it!

      • by FauxPasIII (75900)

        > though it seems strange that they'd route such a dangerous device into an area populated by so many key people

        The EPS (electrified plasma system) is basically the power grid of a starship, it has to go anywhere that needs electricity.

        http://memory-alpha.org/en/wiki/EPS [memory-alpha.org]

        • Re: (Score:3, Interesting)

          by fm6 (162816)

          And this is superior to simple (relatively non-lethal) copper wires because...?

          • by lgw (121541) on Wednesday August 06, 2008 @05:29PM (#24503237) Journal

            You can only put so much current through a busbar. What do you do when a solid copper bar 4 inches across won't carry the power you need? Eventually the size and mass of the busbar required make scaling up in power impractical. For drives, weapons, computer cores, and the like it makes sense.

            Of course, that doesn't explain why the bridge consoles exploded regularly - that's just lowest-bidder construction.

          • by SlowMovingTarget (550823) on Wednesday August 06, 2008 @05:38PM (#24503359) Homepage

            I can think of a number of reasons:

            1. It's harder to run out of magnetic fields than it is to run out of copper.
            2. Exploding Plasma is way cooler than non-exploding copper. I suppose you could make copper plasma, but see number 1.
            3. The old Constitution class used copper wiring, but the space rats and non-corporeal vampiric fart-wraiths kept chewing through it (begin dramatic STOS music). With plasma conduits, the whole ship is one big giant bug zapper.
            4. EPS conduits can also predict pregnancy when you pee on them. I'd like to see your copper wire do that!
  • all is left now is for someone to come up with a warp drive :p

  • horray! (Score:4, Funny)

    by nawcom (941663) on Wednesday August 06, 2008 @02:53PM (#24500891) Homepage

    we will bring the name of Jeebus to Mars before the Apocalypse that Revelations speaks of begins.

    *runs away after starting un-needed religious flamewar*

  • I can see the Big Oil putting a stop to this ASAP!
  • by Anonymous Coward on Wednesday August 06, 2008 @02:54PM (#24500901)

    ...have to be playing Magic Carpet Ride

  • New, it is not (Score:5, Informative)

    by ivanthered (153258) on Wednesday August 06, 2008 @02:58PM (#24500955)

    The VASIMIR has been in developement since 1979.
    http://en.wikipedia.org/wiki/Variable_specific_impulse_magnetoplasma_rocket [wikipedia.org]

    I wonder where they will get the 200 kW to drive it from?

    -------------
    http://borislegradic.blogspot.com/ [blogspot.com]

    • Re:New, it is not (Score:4, Informative)

      by Fast Thick Pants (1081517) <fastthickpants@@@gmail...com> on Wednesday August 06, 2008 @03:04PM (#24501021)
      Sounds like a job for a small, contained nuclear reaction.
    • by qoncept (599709) on Wednesday August 06, 2008 @03:38PM (#24501577) Homepage
      I'm sure in 1979 they could walk in to any corner drug store and buy plutonium, but this is 2008. No, no, the only thing that could generate that kind of electricity is a bolt of lightning, but unfortunately you never know when or where it's going to strike.
    • Re: (Score:2, Interesting)

      by Nef (46782)
      Seriously, it's only 200 kW? That being the case, a few square meters [wikipedia.org] of solar panel should do just fine, even at Mars like distances, you'd still be getting enough energy that it would be trivial ( something like 5 square meters would be sufficient at even Mars furthest distance of 2.5EE6 KM from the sun)

      Yes, I know my figures aren't exact, but this is /., so I'm sure someone will come along and actually do the calculations.
      • Re:New, it is not (Score:5, Informative)

        by Squiffy (242681) on Wednesday August 06, 2008 @04:23PM (#24502283) Homepage

        Seriously, it's only 200 kW? That being the case, a few square meters of solar panel should do just fine, even at Mars like distances, you'd still be getting enough energy that it would be trivial ( something like 5 square meters would be sufficient at even Mars furthest distance of 2.5EE6 KM from the sun)

        Yes, I know my figures aren't exact, but this is /., so I'm sure someone will come along and actually do the calculations.

        From the article you linked, the Earth gets 1366 Watts per square meter. 200000/1366 = 146.4.

        Near Mars, which gets about half of that flux, you need about 300 square meters.

        • by glebfrank (58922)

          Near Mars, which gets about half of that flux, you need about 300 square meters.

          So, a couple of 10 by 15 meter panels. That doesn't sound out of the question.

          • Re: (Score:3, Informative)

            by Squiffy (242681)

            So, a couple of 10 by 15 meter panels. That doesn't sound out of the question.

            I wasn't arguing against the use of solar panels. I was correcting OP's arithmetic.

            I forgot to include a treatment of the actual efficiency of the solar panels we know how to build. We can build 18% efficient panels, and we might have figured out how raise that efficiency to 50%, so the actual area would be between 300/.5 and 300/.18 (i.e. 600-1700) square meters.

        • Another option would be to pump the plasma with solar power directly; a gas like CO would be a good candidate. You can get temperatures of over a million degrees.

          http://www.allbusiness.com/professional-scientific/scientific-research-development/155648-1.html [allbusiness.com]

    • That's easy. A ZPM, you silly person.

  • Engine? (Score:5, Interesting)

    by jdb2 (800046) * on Wednesday August 06, 2008 @03:00PM (#24500981) Journal
    Engine? The scaled down test version might use something "conventional" as its power source, such as an RTG. But, in order for the VASIMIR to work at full-scale, say in a human Mars mission, the power source is going need a VERY large energy density -- something not achievable with any known and tested chemical reaction. I have no idea why they call the power source the "engine" but perhaps it's to placate the environmentalist wackos who will go nuts after hearing the obvious : the "engine" or power source is a nuclear reactor. It will be interesting ( and probably funny ) to see how this plays out in the long run if NASA sticks with this technology.

    jdb2
    • by kestasjk (933987)
      Because NASA have never taken nuclear power sources up into space before..

      (I actually feel like I need to specifically say; they have [wikipedia.org], regularly. Voyager hasn't been sending data back to us for the last 30 years (and the next 30) from inconceivable distances running on biofuel.)
      • Re: (Score:3, Informative)

        by samkass (174571)

        I think the parent poster was trying to differentiate between an RTG (like Voyager has) which relies on the natural decay of radioactive isotopes and a full-bore nuclear fission reactor which induces decay with a neutron chain reaction.

        • by jdb2 (800046) *

          I think the parent poster was trying to differentiate between an RTG (like Voyager has) which relies on the natural decay of radioactive isotopes and a full-bore nuclear fission reactor which induces decay with a neutron chain reaction.

          Exactly.

          jdb2

    • Re: (Score:2, Interesting)

      by avandesande (143899)

      I know this technology is in its infancy but beaming microwave energy to an antenna might work.

    • Re: (Score:2, Informative)

      by luzr (896024)
      Actually, current solar power of ISS is around 100kw (350 m^2 of solar panels).

      So you can perhaps power VASIMIR even using the sun.

      No doubt, small nuclear reactor would be an excellent idea too, especially for Mars and further missions....

    • Re: (Score:2, Insightful)

      by toby34a (944439)
      It will be interesting. However, we've known for a long time that a nuclear reactor would be the best fuel source for a space vessel. Truth be told, it's probably safer to put a nuclear reactor in a spacecraft then in a submarine or aircraft carrier, and the Navy does that all of the time (and it would be more environmental... out in space, you wouldn't have the radioactivity in the oceans). Considering most sub reactors get >100 MW, 200 kW isn't a big deal, and you can power the ship off of it too.
      • Re: (Score:3, Interesting)

        It will be interesting. However, we've known for a long time that a nuclear reactor would be the best fuel source for a space vessel. Truth be told, it's probably safer to put a nuclear reactor in a spacecraft then in a submarine or aircraft carrier, and the Navy does that all of the time (and it would be more environmental... out in space, you wouldn't have the radioactivity in the oceans). Considering most sub reactors get >100 MW, 200 kW isn't a big deal, and you can power the ship off of it too.

        Subm

  • Prepare for wackiness in 3, 2, 1...
  • What is the power source for these drives? Was deep-space I powered purely by solar power? Can that produce enough power to be useful? Or is something like an RTG [wikipedia.org]or a nuclear power source more appropriate? I am also curious as to how much plasma they need to carry with them. I assume they eventually run out, but I gather that a very small amount lasts for a long time.

    It would be awesome to see a purely electrically powered engine that required no fuel mass at all. I guess this is the closest thing we

    • by X0563511 (793323)

      Most likely an RTG would be used, but one "hotter" and shorter lived than what deep space 1 had. After all, it would only need to last a year at most rather than the years upon years the cooler ones go.

    • by rbanffy (584143)

      DS1 was powered by solar panels. They were very high-efficiency compared to other models of the time.

      A nuclear reactor poses another set of problems - it's really hard to get rid of excess heat in a vacuum. Those fins you see between the yellow tanks in the YouTube video are radiators. It's interesting that the ship appears to use three very big RTGs for power placed in long structures far from the crew compartment but the main source of radiated heat seems to be the engine.

      But it's an interesting video.

    • A no fuel mass vehicle is impossible for all practical purposes. Newton's third law: "Every action has an equal and opposite reaction". You can't accelerate a spaceship in one direction without accellerating something else in the other.

      The only possible "exceptions" are an earth based laser propulsion (in which case you are infentesimably accelerating the earth in the opposite direction) or a ram scoop which could pick up fuel as it goes and accelerate that.

  • Make sure you are not an ensign on this ship. Additionally if your in a red shirt it would be best to stay away from the plasma conduits. Or yellow shirt for the next generation of this engine.
  • That plasma is then energised further using radio signals

    I'll bet they're broadcasting the plasma's college fight song to it.

  • by 4D6963 (933028)
    Reminds me that lots of UFOs reported by pilots and military personal are reported to be surrounded by plasma. So if the aliens use that to achieve their blazing speed we must be on the right direction.
  • by mdm-adph (1030332) <mdmadph@nospaM.gmail.com> on Wednesday August 06, 2008 @03:28PM (#24501421) Homepage

    ...and get the ownership rights for the drive squared away before you make the trip to Mars -- the last time this happened, the resulting legal battles (between the UN and some free-love hippie with a strange fixation for water) lasted for years.

  • Can we use this puppy on earth to generate electricity in a cost efficient way?
    • by X0563511 (793323)

      No, this uses energy with fuel to function. What your asking isn't be very far from asking "will an electric motor generate electricity in a cost efficient way?"

      • by swb (14022)

        I think you meant "...in an energy efficient way."

        Because an electric motor will generate electricity in a cost efficient way, provided you're not paying for the electricity input!

      • No, this uses energy with fuel to function. What your asking isn't be very far from asking "will an electric motor generate electricity in a cost efficient way?"

        Seeing as how an electric motor doubles as a simple electric generator ... I think you picked a bad analogy. It's more like asking whether an internal combustion engine can produce gasoline, since the combustion reaction, like the heating and dispersal of the ions, can't easily be reversed.

      • What your asking isn't be very far from asking "will an electric motor generate electricity in a cost efficient way?

        You jest, but in hydro/wind power stations where the rotational frequency of the turbine blades doesn't often match the grid frequency, they used to use electric motors and synchronous machines coupled together to convert between the two.

        Nowadays the push is towards solid state conversion, usually based on IGBTs, which results in convertors which are smaller, cheaper, more reliable and easier to maintain.

  • How about the Franklin drive or Chang-Diaz Drive?

  • by dlapine (131282) <{dlapine} {at} {ncsa.uiuc.edu}> on Wednesday August 06, 2008 @03:41PM (#24501619) Homepage

    Try this Atomic Rocket website [projectrho.com] for some more information on this type of engine outside of Wikipedia. What's interesting about this type of engine is that it's capable of trading thrust (what you want to liftoff) for Specific Impulse (what you want in orbit to get best reaction mass efficiency).

    This is a pretty good site for information on all types of potential/possible/theoretical propulsion systems, and what it would take to do "real" solar system space travel. That being said, space travel (even within the bounds of just our solar system) via our current level of technology bites.

    As someone else noted, this type of propulsion requires about 10MW of electrical energy to function. That energy is not provided by the propulsion system. Something else has to provide it in a compact, dense and energetic form- namely a nuclear reactor onboard the craft. That's why this type of engine shows up at the "Atomic Rocket" website, even though the engine itself doesn't use any nuclear reactions. Some people might not appreciate that the exhaust is not radioactive, as the power plant is just used for electricity.

    Unlike a chemical rocket, a spacecraft using this engine would be able to get to orbit with some payload, and would not resemble "a disintegrating totem pole" getting there. Unfortunately, it also requires a nuclear reactor, a VASMIR engine, a large amount (50-75% of the whole thing) of reaction mass, and probably, wings [projectrho.com].

    • Unlike a chemical rocket, a spacecraft using this engine would be able to get to orbit with some payload, and would not resemble "a disintegrating totem pole" getting there.

      If by "get to orbit" you mean "take off from the ground and travel upward into orbit around the Earth," I don't think this engine is able to do that. Assuming this plot [adastrarocket.com] is correct, 10MW gives you 40 Newtons of thrust (less than 10 pounds) at maximum exhaust velocity. It's great for long trips (like to Mars) where you need as much impulse as possible for a given reaction mass, over a long period of time, but is completely useless for getting off the ground.

      • by dlapine (131282)

        Hmmm, you're correct. The Atomic Rockets [projectrho.com] site shows that while a VASMIR can generate up to 400 Newtons in "low gear", it doesn't have a thrust to weight ratio even close to 1. Darn. I was hoping for a cool "Buck Rogers" style craft. In my excitement I forgot to check the thrust numbers.

        So, any spacecraft using this method requires "a nuclear reactor, a VASMIR engine, a large amount (50-75% of the whole thing) of reaction mass, wings" and some means of getting it to orbit.

        I do think I mentioned that space t

  • How can anyone be a "former" astronaut? I thought once an astronaut, always an astronaut. It's not like they can take going into space away from you.

  • With this kind of speed, I would be concerned with a random piece of dust hitting the ship and possibly tearing a hole in it. I know that orbital debris is a real concern due to the speed at which the shuttle orbits the earth.

    We can see from this website that orbital debris can be an issue:

    http://orbitaldebris.jsc.nasa.gov/photogallery/photogallery.html [nasa.gov]

    What about other forms of space debris? If a ship is moving at such speed to be able to reach mars in 60 days, (that's 1440 hours) and the shortest distanc

  • by reallocate (142797) on Wednesday August 06, 2008 @07:01PM (#24504213)

    This is exactly what needs to be done: Provide more speed.

    Combine that with a cheap and reliable way to get to LEO and you have the beginnings of a real exploration of the Solar System.

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