back to article NASA-backed fusion engine could cut Mars trip down to 30 days

NASA, and plenty of private individuals, want to put mankind on Mars. Now a team at the University of Washington, with funding from the space agency, is about to start building a fusion engine that could get humans there in just 30 days and make other forms of space travel obsolete. FDR Fusion drive Rocket fuel is just so …

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  1. Anonymous Coward
    Coat

    But it takes 2!

    "... obsolete as the stream engine for earth-bound transportation"

    Yes, but you are forgetting the power of crossing the streams!

    Ghost Busters! Ta da da daaaa!

    1. Anonymous Coward
      Anonymous Coward

      Re: But it takes 2lbs of frozen peas

      So am I right in assuming this is just one giant pea shooter?

      1. Ian Yates
        Mushroom

        Re: But it takes 2lbs of frozen peas

        ... Only if your peas can initiate/sustain nuclear fusion

        Very cool tech (no pun)

    2. Bill Neal
      WTF?

      Re: But it takes 2!

      Crossing streams?

      It has the deuterium & lithium, but no anti-matter.

      we probably couldn't get enough solar power to control anti-matter.

  2. dssf

    Astonishing and nice!

    Astonishing, and a great time saver. Since it is claimed to be scalable, imagine what it might do for other mission types.

    Imagine it as a way to grab a sled of exotic asteroid belt minerals, etc, and slingshotting them to earth. The rv could be designed to survive by shielding and parachutes. The engine part could be set up to enter a semi orbit and then shove the rv into a proper descent, and the engin returns to the asteroid belt. If profits and mining are successful and steady, a chain of automated sleds and engines could be synchronized.

    We might become a rep-Warp civilization in under 200 years, maybe even 100...

    1. Wzrd1 Silver badge

      Re: Astonishing and nice!

      Perhaps, the final product will have a new name.

      Such as "impulse drive". ;)

      1. Dave 126

        Re: Astonishing and nice!

        > imagine what it might do for other mission types.

        Diverting asteroids that are heading our way should be on the list!

        1. I think so I am?
          Alert

          Re: Astonishing and nice!

          Also a good way to remove toxic wast an other such things from earth and send them into interstellar space

      2. Richard Wharram
        Meh

        Re: Astonishing and nice!

        Impulse? Meh.

        They should be working towards a conjoiner drive.

        1. Anonymous Coward
          Anonymous Coward

          Re: Astonishing and nice!

          Err...won't that attract the Inhibitors ?

          1. Richard Wharram
            Boffin

            Re: Astonishing and nice!

            Then we'll just use Greenfly to kill the Inhibitors and everything will be fine.

      3. Anonymous Coward
        Anonymous Coward

        Re: Impulse?

        Not keen on 'Impulse Drive'. Names that accurately describe the process are best. The way I see it, bands or 'straps' if you will, exert pressure 'on' the fuel pellet, producing a 'pulse'. It's clearly a 'Pulsating Strap On Drive'

        1. Steve Brooks

          Re: Impulse?

          Pulsing Electric Nuclear Injection System

        2. Trygve Henriksen

          Not PSOD...

          It's a DALEK

          Deuterium ALuminium Electro-Kinetic drive...

          We may need to call the Doctor about the weird noises coming from the control systems...

      4. Tom 13
        Joke

        Re: Such as "impulse drive". ;)

        No what we have now is an impulse drive. This is way more advanced. It's

        an ION drive.

    2. Bill Neal
      Go

      Re: Astonishing and nice!

      When can we expect this to be scaled down to a size appropriate for an F1 car, so race it around the Large Hadron Collider? I want to see Wipeout races in my lifetime.

    3. Matthew 3

      Re: Astonishing and nice!

      "We might become a rep-Warp civilization in under 200 years, maybe even 100..."

      We have to have it done by 2063. Someone with the right surname needs to get busy and make sure there's a lad called Zefram around at the right time.

      1. Greg J Preece

        Re: Astonishing and nice!

        We have to have it done by 2063. Someone with the right surname needs to get busy and make sure there's a lad called Zefram around at the right time.

        Hey, hey, we can do without World War III, thank you very much.

        1. mmeier

          Re: Astonishing and nice!

          WWIII is okay as long as we do the "Mirror Universe" version of First Contact! Shooting (male) Vulcans should be everyones favorit pasttime.

    4. Chronos

      Re: Astonishing and nice!

      dssf: We might become a rep-Warp civilization in under 200 years, maybe even 100...

      Aye, and we may be able to manage being civilised to each other before that, too. Something to look forward to...

    5. AceRimmer1980
      Boffin

      A rep warp civilization?

      So, the spacelanes will be full of FTL white van men. It's theorised that as objects accelerate past c, they lose mass. Hence, contents may be lost in Transit.

  3. MacroRodent
    Thumb Down

    Vaporware

    This and other reporting leaves a bit unclear if they have actually managed to magnetically crunch even a single pellet so that it produces fusion energy. Until they do, it is just vaporware.

    In fact, making the FDR work as explained would mean they have also cracked the problem of making Earth-bound fusion power plants. Write off ITER...

    Sorry, but this smells of too-good-to-be-true.

    (I also wonder why they plan to use solar panels. Wouldn't it make more sense to divert some of the energy from the explosions for running the machinery?)

    1. Wzrd1 Silver badge

      Re: Vaporware

      Sorry, but you confuse fusion energy generation with propulsion, which doesn't necessarily need to generate anything more than kinetic impulse to the craft.

      As the system would be using solar energy to create the magnetic fields and accelerate the fuel pellet, no excess energy is necessary to be released from the engine itself. Hence, without even break-even required for electrical energy generation, the unit would be ineffective for electrical energy generation, but highly efficient at delivering impulses to the spacecraft.

      Though, if there were a CERNesque magnetic coil failure at mid trip, the trip would be rather one way and probably not be survivable.

      1. MacroRodent

        Re: Vaporware

        OK, I see what you mean. Still, there are lots of hurdles. The system for feeding the metal liners into the engine is probably quite complex mechanically, more so than just injecting fluids like in traditional rockets or even ion engines. Probably the worst nightmare for the crew would be to find the mechanism has frozen in place after it has been inactive for days during the coasting phase, and the bracing burn needs to be made.

        1. Michael H.F. Wilkinson
          Happy

          Re: Vaporware

          Of course there are hurdles, that is why research is needed (hence the phrase "if we knew what we were doing it would not be research" ;-) ). There are many ways this can go pear-shaped, but I applaud the aim, and the proposal is plausible enough to investigate further. It is an audacious and exciting proposal.

          This scheme will need a rethink when going to the outer planets such as Jupiter, or its moon Europa, given the much lower intensity of solar radiation. Some other source of electric power will be needed.

        2. David Cantrell
          Boffin

          Re: Vaporware

          They talk about pellets the size of a grain of sand. At that sort of scale, it's not difficult <handwave handwave> to make solids behave like fluids. Or to transport them in a fluid.

        3. Stevie

          Re: Vaporware

          "[more complicated] than just injecting fluids like in traditional rockets..."

          That turns out to be a damn sight more complicated that just about anyone believes. In most cases a small internal rocket is used to drive the turbines that drive the pumps in order to get the incredible volume flow needed.

          This is why multi-engined rockets sometimes fall over instead of soaring majestically skyward, or change their mind and decide to make for the center of the earth instead of LEO. It is ever so easy for something to go wrong and shut an engine down (or quite often just remove it from the universe in a bloody great fireball).

          Science and engineering are hard at the sharp end of spaceflight. One should revere those who get it right as much as one reviles those who get it wrong.

          1. mjones52

            Re: Vaporware

            Yes, vaporware for now, I'll be interested to see how they do, how much progress they might make with this.

            Failure not to be reviled; failure at the very least hints at what to do right. Worst case, as with Edison and his quest for a filament for light bulb, plod along by eliminating all the stuff that doesn't work. Best case, the light bulb goes on, Eureka!, build it right the next time. Wash, rinse, repeat. It's how it's done. Nowadays we can do more things with computer-aided simulations, but it still comes down to bending metal and throwing a switch.

            Interesting re shock absorbers. Sounds worth a try.

            For getting some electricity back, exterior line the exhaust cone with coil - magnetohydrodynamics or somesuch, no?

            Initial juice for outer Solar system and backup and other stuff, just use a standard fission reactor, but do keep the solar panels. Biggest initial penalty is getting the heavy parts off planet; the rest is far lighter re-supply. And if water from asteroids and Moon becomes available, even better.

      2. DropBear
        Thumb Down

        Re: Vaporware

        Um, no. What I just read about was not a system using solar energy to create the magnetic fields and accelerate the fuel pellet, but a system using solar energy to create magnetic fields that will initiate fusion in a fuel pellet resulting in ejection of highly accelerated particles (without that it would be a plain old boring weakling of an ion engine). And that question remains unanswered. HAS THERE BEEN any single "pellet" compressed all the way to fusion yet in practice? Yes or no?

        1. Displacement Activity

          Re: Vaporware

          HAS THERE BEEN any single "pellet" compressed all the way to fusion yet in practice? Yes or no?

          No. It's just a proposal to generate $1B in funding. Here's a 30-page pdf which expands on the summary in the Reg link:

          http://www.nasa.gov/pdf/716077main_Slough_2011_PhI_Fusion_Rocket.pdf

          In short, fusion gain is required to get the necessary energy. The authors discuss Inertial Confinement Fusion (ICF), saying:

          "This Inertial Confinement Fusion (ICF) approach has been actively pursued by the National Nuclear Security Administration (NNSA) of the DOE for decades as it represents essentially a nano-scale version of a fusion explosive device.... It appears that the most promising solution to accomplish this is with a large array of high power pulsed lasers focused down on to the D-T pellet....The National Ignition Facility (NIF) at Livermore National Laboratory is now in the process of testing a laser driven pellet implosion capable producing significant fusion gain for the first time....While the expected energy yield is in the range appropriate for propulsion (E ~ 20- 100 MJ), the scale and mass of the driver (lasers and power supplies) is not, as it requires an aerial photograph to image the full system."

          Hence the cunning plan to use Magneto Inertial Fusion (MIF), where there's some theoretical work to show "that if the imploding shell on to the magnetized target were fully three dimensional, fusion gain could be achieved on a small scale with sub-megajoule liner (shell) kinetic energy. "

          The authors say there are a number of challenges still to be resolved, but "The key to answering all four “hows” stems from current research being done at MSNW on the magnetically driven 3D implosion of metal foils on to an FRC target for obtaining fusion conditions."

          So, Vaporware.

          1. Number6

            Re: Vaporware

            If they got it wrong then it, and some of its surroundings would definitely be vapourware.

          2. Anonymous Coward
            Mushroom

            Re: Vaporware

            > The authors discuss Inertial Confinement Fusion (ICF)

            Actually, I think I get it, they're chucking a bomb out the back, you wouldn't want to do it on earth.

          3. Euripides Pants
            Coat

            Re: "It's just a proposal to generate $1B in funding."

            If the funding falls through and they have to renegotiate, the renegotiated funding would be known as FDR's New Deal...

          4. MacroRodent
            Boffin

            Re: Vaporware

            I went and printed the PDF link you sent (nothing beats dead trees for reading while in commuter train). Halfway throught it, but it certainly answers most questions people have been later posting to this thread. People, read that PDF before posting nonsense! (I wish I had done so myself).

            As you note, the key to the cunning plan is to use a strong magnetic field to make fusion easier. This immediately made me wonder if there were then some less Rube Goldbergian ways to compress the plasma than imploding lithium hoops, which must be a nightmare to manage on a spaceship engine. How about the scheme known to be used in fission bombs: Implode a metal shell with a chemical explosive. This has the advantage that it is known and well-tested technology.

            1. Stevie

              Re: Vaporware

              "This has the advantage that it is known and well-tested technology."

              It has the disadvantage that it is horribly inefficient, requires precision manufacturing of the implosion shell and explosive coating and precision positioning (and activation) of the detonators or nothing happens.

              What you are describing is "Orion".

        2. FrMo
          Pint

          Re: Vaporware

          This question also occurred to me, so I went to the project's website and it repeated the misleading sentence,

          "Nuclear fusion occurs when this plasma is compressed to high pressure with a magnetic field. The team has successfully tested this technique in the lab."

          On reading it further it becomes clear that in their experiments NO FUSION HAS ACTUALLY TAKEN PLACE.

          Yes it seems like a promising project, and it's exciting that it is getting funding, but if they can generate fusion in this way in any reasonable timescale, it will be Nobel Prizes and a place in the history books for them. A whiff of "too good to be true" indeed.

      3. Anonymous Coward
        Anonymous Coward

        Re: Vaporware

        >Sorry, but you confuse fusion energy generation with propulsion...

        Propulsion and energy generation are not unconnected, consider the rotor in an alternator, if you make it go round you can make leccy from it.

        >...the unit would be ineffective for electrical energy generation, but highly

        >efficient at delivering impulses to the spacecraft.

        It's putting out more than 200KW though otherwise where has the energy from the fusion reaction gone?

      4. Anonymous Coward
        Anonymous Coward

        Re: Vaporware

        "Sorry, but you confuse fusion energy generation with propulsion, which doesn't necessarily need to generate anything more than kinetic impulse to the craft."

        Given that the vast bulk of our electricity generation is based on chemical - kinetic - electromagnetic conversions, why can't this be used (in much modified form) for electricity generation?

        You give me some form of controllable kinetic energy, and I'll give you some electricity.

        1. Badvok
          FAIL

          Re: Vaporware

          Have a re-read of the article. In the theoretical space vehicle the electricity is being generated by solar cells, this electricity is then used to power the fusion drive and generate impulse thrust. The theoretical concept is converting solar power into a significant amount of thrust.

          So yes of course we can use the same mechanism for electricity generation - I see them popping up on roofs all the time these days.

          1. Anonymous Coward
            Anonymous Coward

            Re: Vaporware

            "Have a re-read of the article.....So yes of course we can use the same mechanism for electricity generation - I see them popping up on roofs all the time these days"

            Err, you have a re-read of my post and Zanzibar Rastopolous' posts. We're fully aware that in the article electricity is being generated by solar power, and we don't give a stuff. Our identical point was that if you can convert nuclear fusion energy to kinetic energy, Einsteinian intellectuals that we are, we would have thought it relatively simple to convert kinetic energy to electrical energy, like we do for the vast majority of electrical energy on earth.

            1. Badvok
              Facepalm

              Re: Vaporware

              "Einsteinian intellectuals that we are, we would have thought it relatively simple to convert kinetic energy to electrical energy, like we do for the vast majority of electrical energy on earth."

              Not much point in doing that if you are using Electrical energy to generate the Kinetic energy in the first place. Or did you actually think that they are likely to be generating MORE Kinetic energy than the Electrical energy they put in? That has been the unrealised dream of Fusion power research for a long time and we're still 50 years away from being able to achieve it.

              1. David Cantrell
                Mushroom

                Re: Vaporware

                Yes, this would produce more kinetic energy than the electricity put in, when in use. Whether there's a net energy gain I don't know - you have to consider the energy cost of manufacturing the fuel pellets, and of boosting them out of the atmosphere so that you can use them without all those pesky NIMBYs getting cross about the thermonuclear explosions.

        2. Loyal Commenter Silver badge

          Re: Vaporware

          You give me some form of controllable kinetic energy, and I'll give you some electricity.

          Yup, the only problem you need to crack is what to do with those fast moving highly radioactive pellets that you're creating. Not such a problem in space, where everything is bathed in solar radiation anyway, and you're essentially throwing them out behind you.

          1. Spanners Silver badge
            Happy

            Re: Vaporware

            Agreed. That pretty much rules out taking off from Earth or landing back here.

            Doing it do remove a lot of speed prior to re-entry might be OK if you can watch where you point your exhaust.

            Possibly not even a good idea for landing on Mars but might be OK for the moon and asteroids.

        3. 3-I

          Re: Vaporware

          "why can't this be used (in much modified form) for electricity generation?"

          Entropy.

      5. Infernoz Bronze badge
        Mushroom

        Re: Vaporware

        A deflection field failure could occur for several reason e.g. particle impact in the wrong place, and unless detectable, boom, or at the very least lots _more_ Neutron radiation exposure; yes Fusion gives off lots of Neutrons, so there had better be enough Neutron shielding between the engine, and the engine controller and payload! Oh, BTW, the Neutron shielding will eventually become Radioactive and transmuted, so better be easily replaced if reuse is a consideration.

        All this supposes a reliable and affordable system can be produced; if so, maybe we could produce a Fusion version of an internal combustion engine for power generation; yes it's rather low tech, but may work.

        1. Dave 126

          Re: Vaporware

          >My car accelerates rather smoothly to 60mph. This system appears to pulse once per minute. I think that was the OP's point.

          That's probably not an insurmountable issue... shock absorbers.

          1. deMangler

            Re: Vaporware

            I was thinking this. Shock absorbers consisting of lumps of iron in long longitudinal magnetic fields, some kind of coil tube. would dampen the accelleration and could also provide electricity for the next pulse.

          2. Anonymous Coward
            Anonymous Coward

            Re: Vaporware

            >>>That's probably not an insurmountable issue... shock absorbers.<<<

            Project Orion was extensively researched and is not entirely dissimilar in principle, in that you're using a series of nuclear explosions to power your craft.

            They had a big blast shield and shock absorber arrangement, with 1 atom bomb per half second being chucked out the back. So the shock absorber approach doesn't seem infeasible. Getting meaningful fusion is the deal maker/breaker.

            http://en.wikipedia.org/wiki/Project_Orion_%28nuclear_propulsion%29

      6. 3-I

        Re: Vaporware

        "Though, if there were a CERNesque magnetic coil failure at mid trip, the trip would be rather one way and probably not be survivable."

        Well, yes, but the same could be said of most kinds of spaceflight.

      7. John D. Blair
        Holmes

        Re: Vaporware

        I think it has to achieve better-than-break-even performance or you could use an electric ion drive powered from the solar panels. However, perhaps I'm missing something about propellant mass savings due to the high-energy exhaust from the fusion drive (since f = m * a, more acceleration would require less mass).

        Even if it has to achieve break-even, harvesting the energy would be significantly easier than terrestrial power generation: just aim it out the back. No need to absorb the heat w/o destroying the containment vessel, generate steam, etc.

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        2. This post has been deleted by its author

    2. Anonymous Coward
      Anonymous Coward

      I know how fast a car accelerates, but what would be the acceleration of this thing? From what I gather it would be a tad uncomfortable.

      1. Anonymous Coward
        Anonymous Coward

        Let's say your car takes ten seconds to get to 60 miles per hour, over three days at that acceleration you would be travelling at 155520 miles per hour.

        225 million miles average distance Earth to Mars... Trip said to take 30 to 60 days, lets call it 40.

        225 million /40/24 would mean you need an average speed of around 234375 miles an hour. To reach that speed over three days would require less acceleration than that achieved by a sports car.

        1. Ken Hagan Gold badge

          My car accelerates rather smoothly to 60mph. This system appears to pulse once per minute. I think that was the OP's point.

        2. Number6

          Fastest Trip

          For the fastest trip you wouldn't coast at all, apart from a short period in the middle where you changed the way your ship was pointing. Accelerate to the half-way point, turn round, and then decelerate to the destination.

          Of course, the downside is that you'd be going quite fast at turnover, and if there was a failure, you'd be leaving the solar system at quite a speed. You'd also get perforated by a lot of micrometeorites. You'd also need quite a bit of fuel for a continuous drive.

          1. Anonymous Coward
            Anonymous Coward

            Re: Fastest Trip

            why turn around? what's wrong with having an engine in the front as well as the back? just don't fire both of them at the same time or you might be the next "expended pellet" tossed into space ;)

            1. Spanners Silver badge

              Re: Fastest Trip

              Having 2 identical engines would be a waste of resources. You would also have to redefine up & down when you changed over.

              1. Pirate Dave Silver badge
                Pirate

                Re: Fastest Trip

                "Having 2 identical engines would be a waste of resources."

                But it would provide redundancy in case one engine experienced a mechanical failure.

              2. RegGuy1 Silver badge

                Re: Fastest Trip

                Well if it was me I'd have at least two engines. I'd just put them on the same side. I'd go for a concept called redundancy, so if one engine failed I'd at least have one or more left to help me out.

                Failing that I'd have to call the help desk.

                1. Grave

                  Re: Fastest Trip

                  while the aliens used tripple redundancy in clarke's rama, i'd go for a quad redundancy (three is such a pretentious number, lucky my #$% :)).

                  1. primary engine <-> secondary engine = switching between these works on-the-fly without need to turn either on/off

                  2. and then a mirror backup for the entire primary setup (preferably in a different ship section, in a case of a major failure like losing that part of a ship)

              3. Anonymous Coward
                Anonymous Coward

                Re: Fastest Trip

                [quote]Having 2 identical engines would be a waste of resources. You would also have to redefine up & down when you changed over.[/quote]

                incorrect... ender already showed that in 3D space, "down" is where your feet are no matter what your orientation is ;)

                what you might have a problem with is getting oriented properly when the direction you are falling changes but that also depends on how fast that direction changes... as the deceleration phase begins, you will start loosing weight... at the midpoint of the deceleration phase, you aren't going to weigh anything... then you'll start gaining weight again but this time, you'll be on the other couch, chair, wall, whatever...

            2. Grave

              Re: Fastest Trip

              whats wrong with having engine/engines on sides? that way you only have to turn the engines and not entire craft :)

    3. Anonymous Coward
      Anonymous Coward

      Re: Vaporware

      Agree 100%.

      Has it actually fused any pellets so far, and did they measure the force?

      Because, as you say there are certain similarities to what ITER is going to be doing, only ITER is a part of a giant multi-national longterm project who absoluteley don''t have any motivation to make claims beyond what they are currently doing.

      Otherwise, it's drifting perilously close to Orbo, Moller Skycars and top amateur sprinter Andrea "kettle-switch" Rossi

    4. sisk

      Re: Vaporware

      This and other reporting leaves a bit unclear if they have actually managed to magnetically crunch even a single pellet so that it produces fusion energy.

      That's essentially what a polywell device does, isn't it? And according to publically available data they may be able to actually break the all important breakeven point.

      In fact, making the FDR work as explained would mean they have also cracked the problem of making Earth-bound fusion power plants.

      MAKING a fusion plant isn't difficult. There's probably a dozen research fusion plants dotted around the world. The difficult part is getting more electricity out of them than you have to put in to make them work. Since they're using it as a rocket engine that's not a concern.

  4. Jerry H. Appel

    There is no problem with this fusion drive in this scenario. It does need to be pumped by some power source because this system is designed to work without break even mostly because we haven't figured that out yet. The upshot of this system is that the specific impulse is much higher, even higher than a fission system used to heat hydrogen (NERVA concept/prototype).

    I look forward to this system working, but I do wonder what it will take to loft this 150-ton system into orbit – at least a Saturn V class chemical rocket.

    1. John Smith 19 Gold badge
      Happy

      "I look forward to this system working, but I do wonder what it will take to loft this 150-ton system into orbit – at least a Saturn V class chemical rocket."

      Then they will have found an actual use for the SLS apart from keeping a bunch of people in Utah building large solid fuel boosters.

      Of course if NASA wasn't so gun shy of orbital docking and rendezvous they could launch it in sections on rockets that already exist.

    2. Vulch
      Boffin

      "I do wonder what it will take to loft this 150-ton system into orbit"

      The article says about a third of that is payload and the rest could probably be split into two, say the engine itself in one load and the rest of the structure in another. That puts you in range of three Falcon Heavy launches to get everything to Earth orbit, or you could use the ISS type assembly process and launch empty units and fit them out internally via multiple small launches. The engine itself is likely to be the heaviest component and the one you don't want to split further, ideally it goes up in one lump and has labels for "Insert fuel hose here" and the like.

      1. Smallbrainfield
        Paris Hilton

        Would it not make more sense to launch it in parts?

        That way there is less risk to the whole project if one part is lost. Or is one launch less risk than three?

  5. John F***ing Stepp

    Well, yes, go get an astroid. . .

    And hollow it out, put enough engines on it and . . . super slow star trek.

    1. Alan Brown Silver badge

      Re: Well, yes, go get an astroid. . .

      NIce thought, but most asteroids are rubble piles. You need substantial mass to cause it to self-weld together and ones that big are too big for us to even think of handling.

  6. Jolyon Smith
    FAIL

    "200KW of solar panels .. about the same as .. the panels around the ISS"

    Sounds easy when you put it like that, eh ?

    But how about this instead:

    To achieve this, we will need a solar array of just over 3300m2 in area.

    Of course, that's in Earth orbit, and as long as your engine only needs to pootle around in Earth Orbit, that's fine.

    But if you want to go to Mars (or even further out), then as you increase the distance from the sun, the power output from your solar array diminishes exponentially. So you will need much, MUCH bigger solar arrays if you are to derive your electrical power solely from solar (assuming that you are not generating an initial exces of electrical energy which can be stored for use on the return trip - but batteries are heavy, so.... ).

    1. Mike Bell

      Re: "200KW of solar panels .. about the same as .. the panels around the ISS"

      Solar flux varies with the inverse square of distance rather than exponentially. Mars would probably be OK, because it's only 1.7 times further from the Sun than we are.

    2. Mephistro

      Re: "200KW of solar panels .. about the same as .. the panels around the ISS"

      "To achieve this, we will need a solar array of just over 3300m2 in area."

      Or a huge but very thin mirror/sail to concentrate sunlight in a smaller surface, saving loss of mass and weight from the solar panels and raising efficiency. They could keep several of these 'sails' neatly folded in case something goes wrong and the sail is damaged/lost , and for deploying a new sail for the return trip.

      Such a ship would be a bitch to steer, though.

      1. Mister_C
        Pirate

        @ Mephisto

        Back to good old sails then. Explains why the obsolete propulsion method mentioned in the original article was steam. And my choice of icon.

        I agree with your steering concerns. No keel or lee boards possible in near-vacuum.

        1. Phil O'Sophical Silver badge

          Re: steering concerns

          Gyroscopes.

          You'd perhaps also have to hook the motor(s) up to the solaris panel/cabin assembly via something flexible (bungees?!) to even out the impulses for comfort and structural safety.

      2. kyza

        Re: "200KW of solar panels .. about the same as .. the panels around the ISS"

        Must be one of them Lazlo Lyricon custom jobs.

        Looks like a fish.

        Moves like a fish.

        Steers like a cow.

        1. Isendel Steel

          Re: "200KW of solar panels .. about the same as .. the panels around the ISS"

          +1 although it's Lazlar (the older and more talented designer brother of Lazlo)

    3. Timbo
      Coat

      Re: "200KW of solar panels .. about the same as .. the panels around the ISS"

      A large solar array collecting sunlight and converting it to electrical energy sounds OK, as long as you can keep it directed towards the sun and it doesn't become damaged as you are accelerating along.

      Maybe a better idea would be to have a very small nuclear reactor on hand to create the electrical energy ?

      OK, so it would need a lot of shielding, but it could be packaged into it's own re-usable craft, and use it a bit like a railway shunter, moving "cargo" around the solar system.

      1. MrXavia
        Thumb Up

        @Timbo

        Not that unlikely, they are looking at 100Kw fission reactors the size of a 'trash can', two of those and you have your power source...

        Figure a way to absorb and convert some of the kinetic/thermal energy from the fusion into power at the same time, and your laughing!

        (considering they have a stirling engine as the power convertor from the fission, I don't see why they can't absorb some of the thermal radiation and use it to assist the fission reactors!

        I also vote this be called the impulse drive!

  7. Brad Arnold

    LENR emerging soon

    What isn't widely known is that a new clean, very very cheap, and super abundant energy technology is emerging (Leonardo is selling a 1 megawatt LENR generator to a long wait list of customers starting this April - with a COP of about 6, the estimated cost to be about 1/10th that of fossil fuel, and a third-party verification is due to be published soon).

    In other words, the electricity to fuel the fusion engine can be LENR, which has the fuel density of 5 orders of magnitude over fossil fuel. Hydrogen and nickle are common elements throughout the solar system. Here is a primer:

    "A volume about the size of a #2 pencil eraser of water provides as much energy as two 48-gallon drums of gasoline. That is 355,000 times the amount of energy per volume – five orders of magnitude." ( http://oilprice.com/Energy/Energy-General/New-LENR-Machine-is-the-Best-Yet.html ).

    This phenomenon (LENR) has been confirmed in hundreds of published scientific papers: http://lenr-canr.org/acrobat/RothwellJtallyofcol.pdf

    "Over 2 decades with over 100 experiments worldwide indicate LENR is real, much greater than chemical..." --Dennis M. Bushnell, Chief Scientist, NASA Langley Research Center

    "Total replacement of fossil fuels for everything but synthetic organic chemistry." --Dr. Joseph M. Zawodny, NASA

    By the way, here is a survey of some of the companies that are bringing LENR to commercialization: http://www.cleantechblog.com/2011/08/the-new-breed-of-energy-catalyzers-ready-for-commercialization.html

    For those who still aren't convinced, here is a paper I wrote that contains some pretty convincing evidence: http://coldfusionnow.org/the-evidence-for-lenr/

    1. solidsoup
      Devil

      Re: LENR emerging soon

      Aha hhaa ha ha ha. Ha haa ha ha ha. Aha hhaa ha ha ha. Ha haa ha ha ha.

      Please get me up off the floor. Haa ha ha ha. Ha!

    2. Ian Johnston Silver badge
      Thumb Down

      Re: LENR emerging soon

      So, they're going to be selling a commercial cold fusion plant producing 1MW within the next three weeks, a device which would upset much of known and established physics, and they haven't even got a third party verification yet?

      Yeah, sure.

    3. Anonymous Coward
      Anonymous Coward

      Re: LENR emerging soon

      Of course LENR is real, I even saw Keanu Reeves do it back in 1996. So are the zillion over-unity engines one can plainly see demonstrated and working just fine on Youtube (and so is Bigfoot). That paper you mention, it wouldn't happen to be published in a peer-reviewed journal, would it...?

    4. magnetik
      FAIL

      @Brad Arnold - Re: LENR emerging soon

      Stop with your LENR spam, we're bored of it now.

    5. GrantB
      FAIL

      Re: LENR emerging soon

      "...Long wait list of customers starting this April..."

      Yeah, right. Same nameless list of customers who were going to get a device last year.

      I think Ian Bryce has nailed the trick used in these demos, so surprised people are still trying to push this version of the old cold fusion/perpetual motion scam.

      His report can be found linked from here:

      http://www.skeptics.com.au/latest/news/cold-fusion-at-energy-conference/

      Seems like a reasonable explanation, at least without Rossi fronting up with more evidence, a simpler explanation than cold fusion magic.

    6. Colin Miller

      Re: LENR emerging soon

      "long wait list of customers starting this April", would that be the 1st of the month?

    7. kyza

      Re: LENR emerging soon

      Going by the rumbling in my stomach, something else will be emerging soon that bears a striking resemblance to LENR...

    8. Anonymous Coward
      Anonymous Coward

      Re: LENR emerging soon

      Naturally a project of this type needs an input of investment money and it's absolutely in line with expectations and theoretical predictions that the output produces a mixture of primarily oxygen and nitrogen at temperatures elevated above room temperature which proves it is working fully as expected by most serious observers.

      So its conversion efficiency and cycle pathway is exactly what it should be given the methodology, and inline with most predictions.

  8. Neil Barnes Silver badge
    Alien

    Orion Mk 2?

    Ok, Orion used fission instead of fusion, and the reaction mass was ablated from the pusher plate while the reaction mass here is unclear (is it the magnesium around the fusion components?), but it sounds awfully similar.

    And while I think anything that gets humanity's eggs out of this single gravity basket is a pretty good idea, I can't help feeling it could get sunk by the same thing that sunk Orion - the nuclear atmospheric test ban...

    1. Mephistro

      Orion Mk 2? (@ Neil Barnes)

      " it could get sunk by the same thing that sunk Orion - the nuclear atmospheric test ban..."

      Emmm... no. It's not fission, and the elements and materials needed -hydrogen isotopes and lithium- are quite inert and inoffensive -compared to standard rocket fuels- unless you apply energy to them in the quite controlled environment of the engine. It's orders of magnitude safer than sending rocket fuel to LEO to power the trip to Mars. I hope they succeed with this.

      1. Neil Barnes Silver badge

        Re: Orion Mk 2? (@ Neil Barnes)

        Indeed, and I too wish them every success - I want to ride this beast. My immediate judgement would also be that the fuel is certainly safer than the horrible nasties that are even 'safer' rocket fuels.

        But - I'm no expert on the atmospheric test ban, but I don't believe it's restricted to fission. And that would prevent its use in atmosphere by any signatory.

        Though of course, the significant thing about Orion - and one of the things that got it cancelled - was that there was no practical way to get it up without using its fission propulsion from ground leve... this one could well be built in orbit using a kit of bits (I don't think we can get a 150 tone payload up in one bit yet) and it also may be that it's not going to generate 1+g anyway.

      2. Yag

        Re: Orion Mk 2? (@ Neil Barnes)

        "It's not fission, and the elements and materials needed -hydrogen isotopes and lithium- are quite inert and inoffensive"

        Unfortunately, fusion is also included in the Partial Nuclear Test Ban Treaty, and you strangely forgot the point of the fusion products - which may not be as inoffensive as the base materials.

        The PNTB is mostly obsolete however, and the latter can be solved by not using this engine in the atmosphere (the minimal "safe" altitude should be defined, the conventional limit of space is a bit too close to the ground...)

        All in all it's indeed an evolution of the nuclear pulse engine of Orion's fame

        1. Alan Brown Silver badge

          Re: Orion Mk 2? (@ Neil Barnes)

          "you strangely forgot the point of the fusion products - which may not be as inoffensive as the base materials."

          'Hydrogen bombs' as we know them are actually fusion-enhanced fission weapons. The vast majority of radioactives produced are (as always) from the fission side of things and most fallout is a result of the things being fired too close to the ground, sucking up a shitload of dirt and "stuff".

          The small bombs designed for Orion are very clean and easy to build - which is why they're still classified and will probably remain so for a long time. Calculations based on results of atmospheric nuclear testing are that 2-3 people per year would die as a result of the slight increase in background radiation - which is 2-3 people too many for regular launches but might well be justifiable for launching the components of a space elevator, f'instance (vs thousands of conventional launches)

          These fusion pellets should be pretty clean. Current fusion work with pellets results in radioactives with very short halflives, but repeatability isn't something that's been demonstrated (and in my opinion isn't likely to be in a hurry)

          Even so, I tend to agree with Yag - LEO is too close to the ground to light off nukes, even of the pellet variety. The EMP alone would zap a lot of stuff up there.

          That assumes the pellets actually work too.

          1. sisk

            Re: Orion Mk 2? (@ Neil Barnes)

            2-3 people too many for regular launches but might well be justifiable for launching the components of a space elevator

            Unless conventional launches cause deaths due to atmospheric pollution or something even a single death per year is too much for any method of launch.

        2. Mephistro

          Re: Orion Mk 2? (@ Neil Barnes)(@ Yag)

          "Unfortunately, fusion is also included in the Partial Nuclear Test Ban Treaty, and you strangely forgot the point of the fusion products - which may not be as inoffensive as the base materials."

          From reading the article I've found no reference to this engine being used in the atmosphere. I don't think it would make much sense, as A: it's a pulsing engine, providing impulse for a few microseconds every minute and B: the operating environment - hard vacuum vs. Earth's atmosphere- is so different that an engine designed to operate in one would be highly inefficient in the other.

          The engine and the fuel would still need to be sent as cargo in a traditional rocket to reach LEO, but even so it would be hundreds or thousands of times safer than sending traditional fuels to orbit, due to the smaller mass and volume, and the inherent stability of the propellants needed by the FDR.

  9. Steven Roper

    "...would be able to pulse every minute or so and not cause g-force damage to the spacecraft's occupants."

    And how exactly are they going to pull that off? Did they invent the Star Trek Inertial Damping Field while I was asleep or something? Because in my physics book, the recoil from an FDR going off once per minute is going to have much the same effect on the astronauts and all their various clipboards, tools, equipment and bodies floating around in microgravity as firing a gun, getting slammed into the stern wall every time this thing 'pulses'...

    >hmmmmNNNNNNNNZZZZZZ-BANG!!!<

    >crash wham wallop ker-thumpetty thud<

    "Ow! That's the fifth time you've landed on top of me you fat bastard!"

    "Hey, Bob, you seen the way the solar panels wobble on their mounting on that last pulse? Come up here and take a look."

    "Oo-er, they do look a bit wonky there mate, lemme get my toolkit out-"

    >hmmmmNNNNNNNNZZZZZZ-BANG!!!<

    >crash wham wallop ker-thumpetty thud<

    "Haha, ya missed me that time fatso! Wanna try again?"

    "Forget about that mate, one of the panels is definitely coming loose out there, look."

    "Yeh, well if you get off me toolkit I can head to the airlock before the next pulse and go out to-"

    >hmmmmNNNNNNNNZZZZZZ-BANG!!!<

    >crash wham wallop ker-thumpetty thud<

    "FFS this is getting beyond a bloody joke, how long did you say we were accelerating for again?"

    "Well, I'd say not for much longer, because that last one just took the portside panel off..."

    1. Neoc
      FAIL

      <sigh>

      It didn't say "no g-force" it said "no g-force *damage*" (my emphasis). As for the pushes (or "*BANG* as you called them) they would appear, from the description, to be small enough to be felt as a cumulative rather than explosive force.

  10. John Smith 19 Gold badge
    Boffin

    For those just knowledgable enough to be dangerous.

    You're looking at pellets in the 100s of gram range accelerating a vehicle 150 000 bigger. Force = Mass x Acceleration so at 30Km/s and 0.1Kg you get a force of 3000N. By Newtons 3rd law on a body of 150 mt that's about 0.02 m/s, or about 0.002g.

    So no people won't be tripping over each other. The fact it runs for 3 days might have been another clue that would not be happening.

    The short impulse does make it a shock load but the same could be said of the explosions in the cylinders of a car (which this somewhat resembles).

    NIAC is low budget, high risk investment into potentially game changing technology .and they've actually done phase 1 of this. All other fusion proposals have come from a fusion power background where breakeven and electricity generation are key goals. They dumped these and followed the analysis. From their PoV wrapping a fusing plasma in a series of magnetically driven foils (IE thin sheets <1mm thick) is actually a good thing as it gives them more reaction mass to push out the back.

    Note they still have not generated fusion which I think is a pretty big point but if they do that will be a bargain. As for a 200KW PV array keep in mind the ISS array while big is several generations behind the SoA in PV cells, either mult junction or using solar concentrators.

    1. Annihilator
      Paris Hilton

      Re: For those just knowledgable enough to be dangerous.

      I crunched those numbers and came up with similar, but ran into some problems. Using yours (100g pellets, effective recoil of 0.02m/s) lets still consider that this jolt is happening in a microsecond apparently, or 10^-6s. So the acceleration would be 20,000m/s/s at the point of impulse. So it would certainly be an odd sensation.

      Then there's the "pulsing every minute or so" part. The ship is gaining 0.02m/s each minute. So it's average acceleration would be 0.00333m/s/s. After 15 days of constant propulsion (or 1,296,000s) it'll be travelling 4320m/s which sounds pretty nippy, but this is halfway through the predicted journey and we'll only have covered 2.5M km. Somewhat short of the distance to Mars, given the closest known approach is about 22x that.

      What am I missing?

      1. Adam Foxton
        Happy

        Re: For those just knowledgable enough to be dangerous.

        If they build it in orbit, it'd start its journey at the relevant escape velocity and accelerate from there.

        1. John Smith 19 Gold badge
          Meh

          Re: For those just knowledgable enough to be dangerous.

          "If they build it in orbit, it'd start its journey at the relevant escape velocity and accelerate from there."

          No. Escape velocity from Earth is roughly sqrt(2) x orbital velocity

          As any standard mechanics text book would tell you.

  11. Neoc

    Funding?

    Kickstarter, anyone?

    1. Richard Scratcher
      Black Helicopters

      Re: Funding?

      "...Given the tight financial strictures of the US government this is unlikely"

      Just find a military application for this thing and watch the $$$ come rolling in.

  12. K
    Facepalm

    Speed demon..

    And with 200KW, thats enough to power a decent Bose sound system and a few dozen sub-woofers..

    The era of the inter-planatery boy racer begins.

    1. Dave 126

      Re: Speed demon..

      D'oh, I thought that was a reference to the Rastafarian space station in the novel Neuromancer, that featured a substantial sound-system.

      1. toxicdragon

        Re: Speed demon..

        I never did find out what Zion dub was.

  13. Chris Hawkins
    Linux

    Hand the project over to SpaceX

    NASA should have made the funding conditional on the geeks at the University of Washington working with SpaceX!

    This would achieve the following:

    1) A much faster development and implemtation time.

    2) Elon Musk has said he wants to get to Mars!

    This would achieve this objective much more quickly than anticipated and, at the same time, probably please NASA, SpaceX competitors and Anti-Teslans in getting him out the way, especially if the deceleration phase failed and he found himself en route to Titan or Europa!!! (Sorry, Elon! I'm a great fan but the thought does amuse me!)

  14. Vladimir Plouzhnikov

    V1 in Space!

    I want it, go NASA, build one now!

    Also if you add a couple of extra magnetic lenses further down the exhaust you'll get a plasma cannon!

  15. kyza

    So, for those of us who are a bit thick...

    ...by disregarding the need to reach break even point and to keep the whole of the fusion reaction contained inside something solid, by using magnetic fields to direct the plasma, a fusion-engine spacecraft is actually properly feasible?

    This is it in summary, yes? The only real issue is going to be lifting a 150t spacecraft into orbit in the first place (and presumably telling a lot of people not to look at the sky when it starts up, since that would be like staring into a teeny weeny star)?

    I am literally trembling with the potential awesomeness of this project. Please someone tell me the downsides.

    1. John Smith 19 Gold badge

      Re: So, for those of us who are a bit thick...

      "This is it in summary, yes? "

      Correct.

      "The only real issue is going to be lifting a 150t spacecraft into orbit in the first place"

      That's not exactly trivial but there are options.

      " (and presumably telling a lot of people not to look at the sky when it starts up, since that would be like staring into a teeny weeny star)?"

      People look at the Sun (for very short periods) fairly often and (as long as it is short) that does them no permanent harm.

      "Please someone tell me the downsides."

      Well the scale up is pretty substantial. The power array would be the 2nd biggest after the ISS (most PVs on sats are 1/10 the size at most). So far (IIRC) they've demonstrated single shots with Al rings without fusion and this mechanism has to deliver these rings at 1 a minute over 2 three day periods (which is a serious mechanical engineering problem in a space grade vacuum), coupled with dumping enough energy into the pellets (and actual pellet mfg on this scale is pretty substantial as well).

      I guess the key question is how viable is sub-breakeven fusion. This is the critical bit that all those rings wrap round to give the thrust.

      A comparison with the VASIMIR concept (to see what things it shares) might also be useful.

      1. kyza

        Re: So, for those of us who are a bit thick...

        Thanks for the reply John - so there's still a fair bit of science and engineering to be solved but - but it's a probably worth about an 8 on the 'fusion thing worth getting excited about' scale.

        1. John Smith 19 Gold badge

          Re: So, for those of us who are a bit thick...

          "so there's still a fair bit of science and engineering to be solved"

          Definitely. This is far from COTS technology.

          "it's a probably worth about an 8 on the 'fusion thing worth getting excited about' scale"

          With the caveat that this applies for its use as a propulsion technology. The electric power generation application remains as far off as ever.

  16. Laurence78

    Possibility for terrestrial Energy Generation

    Please excuse my ignorance on the subject, but does anyone know is it possible, in theory, that this type of reactor could be used to generate energy on earth?

    1. kyza

      Re: Possibility for terrestrial Energy Generation

      AFAIKS no, because in a terrestrial reactor you need to contain the whole reaction in something and get more energy out than you're putting in to make it worth doing.

      But that's the question in my other post.

      1. Laurence78

        Re: Possibility for terrestrial Energy Generation

        I thought containment might be an issue. But if the reaction is being powered by solar energy similar could be replicated on earth by use of a solar collector. I would also imagine that capturing the energy output of the reaction would also be a challenge.

        This aside, this is still an amazing innovation with very exciting developments as a result.

    2. Ru

      Re: Possibility for terrestrial Energy Generation

      "Possibly", is the anser to that. Extracting a decent amount of electrical energy from the reaction is likely to prove tricky (see also: thermonuclear weapons and fusion power generators), but if they get it working it should be easier than similar technologies like laser and magnetic liner inertial confinement fusion .

  17. Barely registers
    Boffin

    Commercial power generation potential?

    As I understand it at the moment, this system uses the fusion energy to convert a pellet into a 30km/s projectile.

    So why is this not a possible power generation system?

    Fire that projectile into the equivalent of a sand trap, and it will dump its kinetic energy as heat. There's your equivalent of the coal furnace / gas turbine / nuclear reactor. Pump water around it, get steam, add a turbine and voila - electricity. If the fusion is effective enough, you've got a system pushing out more usable power than went into it.

    I'm not saying the engineering is simple, but isn't the premise sound?

    1. AdamSweetman

      Re: Commercial power generation potential?

      The reason this system works well as a propulsion system IN SPACE is that you are dumping everything out the back of the drive in order to go forward, by-products and all. This means you need very little shielding on your system components as the magnetic field effectively directs the whole lot away from the squishies up front, think of it as big exhaust, that's it.

      The difference when trying to use this technique as a power generation process is you have to handle not just the energy from the fusion reaction (to get your power) but the neutrons and waste as well, this means tons of shielding which needs to be replaced very frequently and is highly radioactive. Theoretically you could attempt magnetic confinement but that's the same engineering challenge as ITER etc. Confinement is a drastically different prospect that simply directing the whole lot in one direction into nothingness.

      There are promising fusion power generation techniques emerging, including several aneutronic solutions, my bets would be the guys at LPPX or Polywell (EMC2), but tri-alpha looks pretty close as well. As Bussard said, the challenge is not the physics, the challenge is the politics.

    2. John Smith 19 Gold badge
      Unhappy

      Re: Commercial power generation potential?

      "If the fusion is effective enough, you've got a system pushing out more usable power than went into it."

      That's the point.

      It is not that efficient.

      The goals of space transport and Earth power generation are sufficiently different that this concept is good enough to push things around in space but not good enough for Earth power generation.

      The latter (it turns out ) is much harder

      1. Christoph

        Re: Commercial power generation potential?

        If it doesn't put out more usable power than went into it, then what is the point?

        Why not use the power to accelerate the propellant directly such as an ion engine? Why bother with all the extra gubbins at all?

        1. Alan Brown Silver badge

          Re: Commercial power generation potential?

          Because even using ion drives the exhaust speeds achieved are such that you need a metric shitload of reaction mass - more than is practical to take into orbit.

          Fusion exhaust is much _much_ faster, otherwise you may as well use a 200kW ion drive.

        2. Vulch
          Boffin

          Re: Commercial power generation potential?

          Usable power for power generation is a very different thing to usable power for propulsion. I would expect this engine to actually produce more energy than was used to trigger it, but it won't be in a form that can be siphoned off to trigger the next bang.

        3. John Smith 19 Gold badge
          Meh

          Re: Commercial power generation potential?

          "Why not use the power to accelerate the propellant directly such as an ion engine? Why bother with all the extra gubbins at all?"

          Try and find an Ion drive with a thrust of 3000N while retaining an Isp of c3000secs.

          1. hayseed

            Re: Commercial power generation potential?

            Well, that's a frontier also, getting ion drives up to reasonable thrusts (right now they are mainly used on Russian satellites for station-keeping)

            1. John Smith 19 Gold badge
              Boffin

              Re: Commercial power generation potential?

              "Well, that's a frontier also, getting ion drives up to reasonable thrusts (right now they are mainly used on Russian satellites for station-keeping)"

              You're missing the point. An SoA big ion drive is about 100x smaller than that. They do not gang together very well (plume interference) and the power level needed for a 3000N thruster will be in the MW range at least.

              The solar energy is used to run the machinery and trigger the fusion burn, which amplifies the energy you actually have to collect and store, but in a way that gives good thrust but poor options for collecting electricity out the back. This trade off is viewed as acceptable for a propulsion system (less shielding as the liners act like disposable radiation shields, renewed after every shot). Likewise the pulsed nature virtually eliminates cooling needs given the low duty cycle (completely unacceptable in common fusion power architectures) and so on.

  18. This post has been deleted by its author

    1. Smallbrainfield
      Paris Hilton

      Re: I don't get it

      You'd need to put the same energy in at the other end to stop. Perhaps it uses too much energy?

      You would be travelling a lot faster but the window for turnaround would be far smaller. Wouldn't want to overshoot as it's a long walk home...

    2. Vladimir Plouzhnikov

      Re: I don't get it

      "Well could you not run the engine for 6-7 days to go even faster and get there in half the time?"

      I believe you could but at twice the expense in fuel.

    3. Marcelo Rodrigues
      Boffin

      Re: I don't get it

      It is a reaction engine: You accelerate something, and the reaction pushes the ship forward.

      The thing being accelerated gets up to 30 km/s (if I got it right). So, this is your maximum speed: 30 km/s. I believe that, after 3 days, the spaceship would be at that speed - or close enough to make no difference.

      That would be why You turn off the engine after 3 days - would make no difference.

      1. Vladimir Plouzhnikov

        Re: I don't get it

        "The thing being accelerated gets up to 30 km/s (if I got it right). So, this is your maximum speed"

        No, no, it doesn't work like that!

        There are many ways of looking at this but it you consider the conservation of momentum, your spaceship is a system with momentum of mass times velocity. If you throw some amount of fuel mass at some exit velocity, that fuel will have negative momentum (because the velocity of fuel is negative comparing to the velocity of the ship). Therefore, the ship must compensate by increasing its momentum by the same amount. Because the mass of the ship is only going smaller (as the fuel exits) it is the velocity that must be getting higher.

        Consequently, as long as you continue to throw fuel (reaction mass) out the back of the ship it will continue to accelerate, regardless of the maximum speed at which the reaction mass can fly away. If you have enough fuel, your ship will eventually approach the speed of light (when it will hit the relativistic limits).

        1. Destroy All Monsters Silver badge

          Re: I don't get it

          Rocket Equation

        2. Marcelo Rodrigues
          Pint

          Re: I don't get it

          I didn't know that! We learn something new every day... :D

  19. Chris Ashworth

    This engine converts electrical energy (from a big solar array) into kinetic energy, via fusion.

    It is not a generator.

    1. Vladimir Plouzhnikov

      I think it converts potential energy of the fuel nucleons into kinetic energy of the fusion products in the resulting plasma. The electrical energy is only used for triggering the reaction and for containment and is not added to the balance but is actually subtracted. Or so it seems to me...

      P.S. Or both added and subtracted, to be precise, so its total contribution is 0

  20. Anonymous Coward
    Boffin

    What about shielding?

    Genuine question to those who have better understanding than me.

    Lets assume that, because of the length of time in space is reduced considerably and conventional radiation shielding being suitable, what about shielding against physical space debris. Indeed, is this a problem?

    Making the assumption that the max speed would be approx 350,000 mph, what is the problem of physical matter, indeed if much at all? I mean we are talking about 0.05c here at max speeds. Granted odds are in favour due to smaller timeframe but then I am making assumptions just how dirty this part of the solar system is. Or am I making issues out of small odds of becoming a very pretty but brief star in the night sky?

    1. This post has been deleted by its author

    2. Anonymous Coward
      Anonymous Coward

      Re: What about shielding?

      I should have clarified. Im curious - if small flecks of paint and other assorted microscopic debris can mark the Space Shuttle windows in orbit, a tiny piece of matter hitting the craft at combined speed potentially in excess of 400k mph then what kind of damage would that ensue?

      1. Remy Redert

        Re: What about shielding?

        A small fleck of paint at interplanetary speeds would not just mark a window. It would likely put a hole a right through it.

        However high speed collisions like that are easy to shield against with a whipple shield but you probably don't want any windows in the front.

        As for breakeven. Don't forget that for breakeven in a fusion electric reactor you have to get your fusion and then convert the energy from that fusion into electricity. And thermodynamics being a pain in the butt you're going to be losing a bunch of energy to low grade heat there. The propulsion system has much lower inefficiencies and so reaches breakeven much more easily.

        You put 200kW in and get more out in kinetic energy, so straight up ion will be less efficient. VASIMR will require a larger powerplant but I'm not sure if it can get a higher specific impulse out of the reaction mass.

        1. Alan Brown Silver badge

          Re: What about shielding?

          "A small fleck of paint at interplanetary speeds would not just mark a window. It would likely put a hole a right through it."

          Through the window, through the seat, through the back wall and every other wall until it exits the ship again.(*)

          (*)Unless you thaw it out first.

          This is one reason why designs built _heavy_ are generally favoured over the usual balsa-and-paper approach of conventional spacecraft design, especially at the kinds of speeds being considered.

  21. Avatar of They
    Thumb Up

    I frikkin love science

    That is all.

  22. This post has been deleted by its author

  23. Anonymous Coward
    Anonymous Coward

    isn't there enough trash in space already?

    so here we are trying to figure out how to clear the debris mess from earth orbit plus we're looking at planetary debris that could destroy our home and yet we're going to throw more trash into space with this new fangled drive system? there's enough problems dealing with grains of sand traveling at 25000+mph already...

    1. kyza

      Re: isn't there enough trash in space already?

      I don't think there'd be too much trash left after it's been through fusing plasma.

    2. Grikath

      Re: isn't there enough trash in space already?

      There is a helluva lot of difference between the space debris in earth orbit, and the exhaust products of a rocket engine, including this one.

      - If they manage to get this thing going the exhaust product is the result of nuclear fusion , which tends to be rather ...hot. The pellets leave the exhaust as a plasma, so any "debris" would be near indistinguishable from the local micro-stuff naturally present.

      - Simple ballistics shows that any exhaust product for a trajectory away from earth will not have the correct vector for an earth orbit. Even more so, as the vessel picks up speed eventually the net vector of the exhaust products will be *away* from earth.

      1. Ryan 7
        Alert

        Re: There is a helluva lot of difference

        Actually, you're right. As soon as they start decelerating at the other end, they'll get a column of exhaust catching up, and smashing into them!

        Probably best to pack some small hydrazine thrusters to step to the right and let it all fly past.

        1. Frumious Bandersnatch

          Re: There is a helluva lot of difference

          As soon as they start decelerating at the other end, they'll get a column of exhaust catching up, and smashing into them!

          No. First, you have to understand inertial frames of reference. If I'm on the roof of train and I fire a gun in the forward direction, it will have the same apparent velocity (to me, and ignoring air resistance) as a bullet fired in the "backwards" direction. Despite being in motion, the relative velocities still work out the same as if we decide that (or it's actually the case that) the train is fixed in space. This is our "inertial frame of reference". Second, you need to take into account Newton's third law: "for every action there is an equal and opposite reaction", which is the principle behind any "reaction drive", of which this is an example. Again, consider the plasma exhaust coming out of our "gun". It has a mass that is a tiny fraction of the mass of the ship, but will have a large acceleration. Since F = ma (force = mass x acceleration) and due to Newton's third law, our ship will have a balancing (reaction) force propelling it in the opposite direction to the plasma. Since the ship's mass is so many times larger than the projectile, the resulting deceleration will be much less than that experienced by the projectile.

          So in summary, (1) the projectile will always accelerate away from the ship, regardless of which direction we're going, and (2) catching up with the exhaust assumes you're going forward-backward-forward for some reason, rather than forward-backward, and even then, the chance of hitting the exhaust over such vast distances is crazily small. Also, (3) detonating the pellet and turning it into plasma means that after a short time there won't be anything except a diffuse gas for anything (including other ships in the vicinity) to collide with anyway.

  24. JeffyPooh
    Pint

    And all it requires is just a wee bit of fusion

    I think it'd be faster to walk to Mars than wait for fusion to be practical.

    1. Phil O'Sophical Silver badge
      Coat

      Re: And all it requires is just a wee bit of fusion

      Fusion is entirely practical, there are several large glazed craters in deserts to prove it.

      1. JeffyPooh
        Pint

        Re: And all it requires is just a wee bit of fusion

        Good point. Well done. You missed the other obvious counter example, the Sun. My post was overly brief leaving it just wrong.

        So ...all they need to do is shrink an H bomb down to the size of a tiny pellet, and we're, like, there already.

  25. magrathea

    why not just use the electricty to accelerate a gas (or something) using a conventional technique?

    An expensive, complicated mechanism that reduces efficiency somewhat. Is this a government project?

    1. Yag

      Re: why not just use the electricty to accelerate a gas ?

      Simple : the acceleration of a gas via electric means can have a theorical best of 100% conversion rate from electric energy to kinetic energy. You use 1kJ of electricity to get 1kJ of kinetic energy.

      Of course, this is assuming a lot of physical improbability like zero losses...

      Using electricity to trigger the fusion of a pellet will consume both the electricity (not much) and the nuclear energy stored in the pellet (a lot more). The same kJ of electricity will generate several dozens or hundreds of kJ of kinetic energy (A physicist would be far better than poor me to compute the actual value... Feel free to correct me in this case)

      Think of the 'leccy as the few pounds of conventional explosives needed to trigger a several kilotons atomic bomb.

      1. magrathea

        Re: why not just use the electricty to accelerate a gas ?

        That's fine, but it amounts to claim that the fusion process here returns more energy than it consumes.

      2. JeffyPooh
        Pint

        Re: why not just use the electricty to accelerate a gas ?

        How about they use a fusion reactor to make the electricity to accelerate the gas? Fusion reactors are, like, a dime a dozen - right? Especially the ones that zap pellets. Easy peasy.

        Same concept as the external blaster, but it's like 'internal combustion' version. Pollution standards DO apply in outer space ya know. It's not like your allowed to drift through the solar system belching radioactive isotopes, bloody hillbillies.

        1. Vance P. Frickey
          Mushroom

          Re: why not just use the electricty to accelerate a gas ?

          Good question: the US Navy has the answer. They're developing a refinement of the Farnsworth-Hirsch Fusor - an electromagnetic grid/inertially-confined fusion reactor that can run on tritium, deuterium, or boron-11. The basic configuration theoretically can be four meters across and develop a gigawatt.

          Following me yet? A four-meter gigawatt reactor with very compact fuel can use Lorentz electric rockets to expel a number of ionizable working fluids (lithium perhaps the most practical) at very, very high specific impulse.

          Perhaps the specific impulse from using the gigawatt of electricity from the USN's compact fusion reactor to run one or more Lorentz engines is not as high as a thermonuclear detonation, but the scheme would be much, MUCH cheaper, less politically fraught (since the article is basically describing something that could be altered to be a fully-automatic, high rate of fire micro H-bomb cannon here on Earth or up in the satellite belt), and very scalable.

        2. Yag

          Re: why not just use the electricty to accelerate a gas ?

          "How about they use a fusion reactor to make the electricity to accelerate the gas?"

          You'll need to ignite the pellet, then convert the heatand/or kinetic energy of the reaction to 'leccy, then convert back the leccy to kinetic energy. quite unefficient.

          A NERVA-like configuration would be a bit simpler and more efficient : you ignite the pellet, then heat the gas directly. And it might retain your "environment friendly" point.

          The proposed configuration is the more direct and efficient approach.

  26. FutureShock999
    Pirate

    The Kzinti Lesson...

    This is it - the perfect combination space drive and space weapon. Now we are ready to fight the Kzinti when we meet them...and their telepaths will report that humanity has NO WEAPONS of any kind on their ships...hehehe.

    (props to Larry Niven, of course)

    1. magrathea

      Re: The Kzinti Lesson...

      The Kzin could learn no lessons from mere Humans on the suitability of a fusion drive as a weapon. Your inference is insulting and I demand you withdraw it.

  27. Alan Brown Silver badge

    Acceleration levels which won't smear the occupants over the walls

    But will they be low enough to ensure the solar panels don't get ripped off?

    We've had the technology to go to/from mars with 30,000 tons of payload in 90 days since the 50s in any case. There's just the pesky issue of a prohibition on atmospheric nuclear explosions to deal with.

  28. Paul Smith

    1) Propulsion not generation - Pretend the engine is a magic black box run by the solar panels. It does not have to be efficient, it has to get you to Mars (and back). If the solar panels dont produce enough power for a pulse a minute, run the engine for twice as long at a pulse every two minutes.

    2) Waste products - A pellet the size of a grain of sand ejected at 30Km/s, every 60 seconds will leave a trail of one grain of 'hot' sand, every 1,800 Kilometers.

    3) Shock - Fit shock absorbers.

    4) Atmospheric Test Ban Treaty - This only applies to explosions. We are merely generating intermittent reactions.

    1. Anonymous Coward
      Anonymous Coward

      I still don't see a single example of a "working" system. Propulsion or otherwise.

      We can use rocketry to power generators. It would be crazy and inefficient, but a "proof of concept" could be made and work.

      This shows neither so far.

      Basically, if they swapped the magnetic pinch for a laser system, then what questions would we ask? We would ask "but we don't have a working laser fusion system yet (generator or otherwise)?" Is it correct that we do not have a working laser fusion system yet? If we do have a working system, why is it proposed to use a magnetic pinch, and not a laser system?

      Either one would work, either one can be used for both?

  29. Stevie

    Bah!

    It will work because it has the word "fusion" in it!

    Wait...as you were. I think I have that wrong. Ah. I see the problem. Let's have another go:

    It will eat vast amounts of cash for no discernible result because it has the word "fusion" in it!

  30. J.G.Harston Silver badge

    Hurray!!!

    At last, somebody's developing constant-acceleration engines, as compared to the constant-velocity engines we've been relying on for the past half century. At a constant 1g you can get to Mars in a day or so.

  31. Guardius
    Thumb Up

    I have never seen a more interesting Kickstarter opportunity than this. There are plenty... PLENTY of people out there who would toss in some money to see this happen quickly.

  32. Boris the Cockroach Silver badge
    Happy

    And why

    does the first picture look like something built in Kerbal space program?

    Although their space ships look somewhat better than the effort above

  33. ecofeco Silver badge
    Meh

    Not holding my breath

    Been hearing about fusion engines for decades.

    Wake me when it actually flies.

    ...and they figure out the forward shielding.

  34. sisk

    Solar panels??

    Doesn't the usefulness of solar panels degrade pretty much to "useless" once you get much further out than Mars? I get that right now Mars is the goal, but there are moons out further that might also, with a good enough energy source, be colonizable (yeah, yeah, now I'm making up words). Or, in the nearer term, this could be used to make mining asteroids a little more feasible, but only if you have enough power when the sun's a lot further away than it is on Earth.

    1. itzman
      Mushroom

      Re: Solar panels??

      no big deal. A fission reactor can easily kick out 200kw or so.

      1. John Smith 19 Gold badge
        Mushroom

        Re: Solar panels??

        " A fission reactor can easily kick out 200kw or so"

        On Earth

        In orbit a 5Kw fission electricity reactors is big (and Russian).

        OTOH if you go for thrust the NERVA design had power ratings in the GW range but a T/W of about 7:1 and an Isp of maybe 1/3 of this design (and LH2 is a pig to handle).

  35. Anonymous Coward
    Anonymous Coward

    Space debris

    if the spent pellet is ejected from the craft as opposed to being ejected in the form of heat compression and light would that result in an increase in space debris surrounding our and other planets? Will this contribute to the existing debris problem around earth and potentially around other planets?

  36. James Hughes 1

    Stunning

    I reckon if the average Reg commenter had been the average human over the last 5000 years, we would still be living in caves. Such negativity for what is a RESEARCH PROJECT. You know, one of those projects designed to RESEARCH in to the feasibility of the end result. If Reg readers were in charge, it would all be "Nah, that won't work 'cos of some back of the envelope calc I did, and 'cos I know better than a bunch of scientists who know about this shit 'cos I've got a degree in drama and knitting"

    C'mon people, give these guys a break. They have an idea, they've got some money to test it. This is a GOOD THING.

    It's very surprising how many Reg readers should be working in the bleeding edge space rocket field rather that tech, judging by the comments above. They would really show these morons at NASA how to do it. Can't believe you people are not working there already.

    1. Destroy All Monsters Silver badge
      Trollface

      Re: Stunning

      Why do you want to put social science majors reconverted as webmonkeys into engineering?

      1. James Hughes 1

        Re: Stunning

        I don't. I want the people who are already there, have all the requisite experience, and are, lets face it, much better at rocket science than everyone here, to be working on this sort of stuff. I'm just making the point that a bunch of commentators here seem to think they know more than aforementioned people, and yet their qualifications are, lets assume, somewhat less applicable. (Drama and knitting...)

    2. Anonymous Coward
      Anonymous Coward

      Re: Stunning

      Is the confusion over the reporting or the science?

      If the project is for research then fine. If it's pie in the sky, they can get in line with all the other media and entertainment industries. Keep the line of science as far away from the line of pure speculation as possible.

      I'm sure this project is aiming for realistic goals. But if they are trying to run before they can walk, they may trip up.

  37. Anonymous Coward
    Anonymous Coward

    Direct versus Indirect Fusion Propulsion

    I think direct fusion propulsion will hardly work because the Lawson criterion(density, confinement time and temperature), most of the unburned fuel will be expelled out; it will be a big waste of fuel. A better option is a fusion reactor with closed-cycle for recycling the unburned fuels, and indirect propulsion using electric thrusters. http://youtu.be/VUrt186pWoA

  38. Vance P. Frickey
    Mushroom

    The US Navy has a better idea...

    ...they're developing a electromagnetically-confined fusion reactor in San Diego, CA that can use tritium, deuterium, or boron-11 as fuel. The energy comes out in two ways - heat from the fusion reaction (heating a working fluid as fission reactors do) and electrical current from the metal grids as stray electrons and alpha particles from the boron-11 + proton reaction are captured there. It's essentially a further development of the Farnsworth-Hirsch fusor.

    While the USN wants a small (a 1 gW reactor could be as narrow as 4 meters across) nuclear reactor that would produce lots of power from more manageable and less expensive fuel than 90% uranium-235 (the current naval reactor fuel) for its fleet of new, electrically-propelled, railgun-armed destroyers, NASA and the US Department of Energy have been working with Russian-developed technology for rocket engines that have very high specific impulse without actually using thermonuclear detonations: Lorentz electrodynamic rocket engines.

    The combination of the US Navy's Polywell fusion reactor driving a set of Lorentz electrodynamic rocket engines would be quite a lot cheaper than the thermonuclear detonation-propelled model. The fewer bucks it costs to play Buck Rogers, the more likely we'll get to do it.

    1. Silverburn
      Happy

      Re: The US Navy has a better idea...

      ...further development of the Farnsworth-Hirsch fusor...

      I knew Futurama would come into this somewhere. No mentions of the Farnsworth paradox yet tho'...

  39. Parax
    Alert

    Too many Errors

    "compress lithium or aluminum metal bands around a deuterium-tritium fuel pellet to initiate fusion."

    "A pellet the size of a grain of sand " - if you ignore the compression bands

    "mean that the spacecraft could power itself on solar energy alone." - if you ignore the compression bands and fuel pellets.

    So it needs fuel pellets, and new compression bands for every pulse, So it most certainly can not function "on solar energy alone".

    When you can do this without wasting the compression bands then it'll be more interesting. I don't know how you could do this though, other than going back to Solar powered laser confinement, maybe Lasers Are the answer.

  40. Anonymous Coward
    Alert

    This is great...

    ...but I'd definitely advise against sending Sam Neil on the inaugural mission.

    1. Derpity
      Coat

      Re: This is great...

      Surely this event is just there on the horizon.

  41. Silverburn
    Holmes

    Smooth ride?

    Obvious question - won't the constant on/off shunting of thrust every minute give you a splitting headache or make you seasick?

    Even smaller charges but at subsecond internals (1500-2000 per minute, say) will surely provide a better ride for the occupants and any sensitive equipment onboard, while providing the same rate of acceleration.

    Naturally, I'm completely ignoring the practicalities of getting this to work...

    1. John Smith 19 Gold badge
      Facepalm

      Re: Smooth ride?

      "Naturally, I'm completely ignoring the practicalities of getting this to work..."

      In fact you're completely ignoring the article's contents.

      RTFA.

  42. itzman
    Mushroom

    A simpler way to harness fusion power

    ..I have always thought that a simple internal combustion engine built of pure ceramic that sucked in hydrogen, compresses it mightily and ignited it with a laser pulse 'spark plug' working in a 4stroke principle would be the ideal motive power for my new jaguar.

    Indeed use of water instead of hydrogen would be even more ideal, with the steam as well as superheated hydrogen being the working fluid..

    Never mind all this steady state containment nonsense to achieve continuous fusion. We have being using explosions to drive around for a century.

    Bring back the rolls royce 'gandalf' 24 cylinder fusion engine

  43. Herby

    Magnetic confinement...

    Dick Tracy and his buddy Diet Smith would be proud.

    Using magnetic stuff is what it is all about!

  44. John Smith 19 Gold badge
    Happy

    Bottom line. *Potentially* efficient enough to get the propulsion job done

    But not continuous power generation.

    But if it gives us Mars in 30 days WTF cares?

  45. Van

    Bottle

    It's going to be much cheaper to send a man the long way and one way only. There won't be a shortage of volunteers, only the shortage of bottle from an organization to make the unethical decision.

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