≡ Menu

Mini-Mag Orion: A Near-Term Starship?

Physics breakthroughs aside, are there more conventional ways we can reach the stars? Centauri Dreams often cites (with admiration) Robert Forward’s work on beamed laser propulsion, which offers a key advantage: The spacecraft need carry no bulky propellant. Forward’s missions involved a 7200-GW laser to push a 785 ton unmanned probe on an interstellar mission. A manned attempt would involve a 75,000,000-GW laser and a vast vehicle of some 78,500 tons. The laser systems involved in such missions, while within our understanding of physics, are obviously well beyond our current engineering.

Are there other ways to accomplish such an interstellar mission? One possibility is a hybrid system that combines what is known as Miniature Magnetic Orion technologies with beamed propulsion. The spacecraft would carry a relatively small amount of fission fuel, with the remainder of the propellant — in the form of particles of fissionable material with a deuterium/tritium core — being beamed to the spacecraft. In a recent paper in Acta Astronautica, Dana Andrews (Andrews Space) and Roger Lenard (Sandia National Laboratories) describe these technologies and their own recent studies of the Mini-Mag Orion concept.

Mini-Mag Orion, of course, harkens back to the original Project Orion, an attempt to develop a spacecraft that would be driven by successive detonations of nuclear bombs. Mini-Mag Orion takes the concept in entirely new directions, reducing the size of the vehicle drastically by using magnetic compression technology, which Andrews and Lenard have studied using Sandia National Laboratories’ Z-Pinch Machine, the world’s largest operational pulse power device. Their experimental and analytical progress is outlined in the paper referenced below; they now propose a follow-on program to extend their experimental work.

Mini-Mag Orion

The originally envisioned spacecraft would compress small fuel pellets to high density using a magnetic field, directing plasma from the resultant explosion through a magnetic nozzle to create thrust. This highly efficient form of pulsed nuclear propulsion is here paired for interstellar purposes with beamed propulsion methods, taking advantage of a pellet stream that continuously fuels the departing spacecraft. The interstellar Mini-Mag Orion attains approximately ten percent of light speed using these methods, and as Andrews and Lenard show, the hybrid technologies here studied reduce power requirements from the departing star system and the timeframe over which acceleration and power have to be applied.

Image: The Mini-Mag Orion interstellar concept, a hybrid starship accelerated by beamed pellet propellants, and decelerated with a magnetic sail. Credit: Roger Lenard/Dana Andrews; Andrews Space.

With the bulk of the propellant being supplied externally, deceleration in the target star system is an obvious challenge, one met through the use of a magnetic sail. Here is the authors’ explanation of what is essentially ‘free’ deceleration:

In 2003 both Andrews and Lenard postulated using a large superconducting ring to intercept charge particles in interstellar space to slow the spacecraft down from high speeds. Additionally, the solar wind emanating from a star system provides an additional source of charged particles that can interact with the magnetic field. Deceleration can actually begin a sizable distance from the target star system… [T]he first phase of the deceleration starts at 21600 AU with a two-turn superconducting carbon nano tube reinforced loop. This loop captures the charged interstellar medium and deflects it to decelerate the spacecraft. This initial hoop size is 500 km in radius and carries 1,000,000 A of current. The spacecraft decelerates from .1 c to 6300 km/s by the time the spacecraft reaches 5000 AU. This will be quite a light show, so if there are any intelligent life forms with an observing system, they should be able to see the arrival.

Quite a light show indeed! But note this: Even in the absence of a paradigm-changing physics breakthrough, Andrews and Lenard, as Forward before them, have demonstrated that there are ways to reach nearby stars with technologies we understand today and may be able to build within the century. Assume methods no more advanced than these coupled with advances in biology and life extension and it is conceivable that long-lived human crews could populate the galaxy in a series of 60 to 90 light year expansions, an interstellar diaspora that, the authors calculate, could occur every four to five thousand years.

Work out the numbers and you get half the galaxy populated within a million years (Fermi’s question again resonates). The paper is Lenard and Andrews, “Use of Mini-Mag Orion and superconducting coils for near-term interstellar transportation,” Acta Astronautica 61 (2007), pp. 450-458.

Comments on this entry are closed.

  • Adam August 29, 2007, 15:48

    Hi Paul

    Wish I could read it. Not being attached to a University is a real pain sometimes, especially when fun papers like that get published. Hibernation and/or life-extension would make such star-jumps pretty reasonable – if a people group was motivated enough to make the interstellar leap. Why the 60-90 light-year range?

  • Brian Wang August 29, 2007, 15:52

    This is fantastic. I had been looking for what the latest news was on mini-mag orion projects and concepts.

  • Administrator August 29, 2007, 16:18

    Adam, here’s the actual quote with reference to the 60-90 light year range:

    “Assuming that breakthrough physics does not yield a new propulsion concept, we are certainly on the verge of a new biology. We should reasonably expect that human lifespans could, at some point in the future, achieve antediluvian proportions. Given our former fractional time breakout, this means that a crew could ostensibly travel for 600 years and still be in their prime at the destination. This would mean that humanity could populate the galaxy in 60.90 LY spheres. Given the sophistication of humans and robots at that time, we could expect a new Diaspora to occur every 4000 to 5000 years. In a million years, half the galaxy could be inhabited.”

  • Kurt9 August 29, 2007, 17:35

    Barrow, Tipler, Dyson, and many others have been saying this for years. Freeman Dyson has repeatedly said that there can be only one technological civilization per galaxy. The fact that our galaxy appears to be empty suggests that either 1) we are alone, or 2) that a technological civilization passes through some kind of singularity or technological transcendence long before it spreads about the galaxy, making them invisible to us.

    I simply do not see any other credible explanation for extraterrestrial intelligence.

  • andy August 29, 2007, 18:03

    Then again, you’ve got the assumption that we can bio-engineer ourselves to have long lifetimes, or that hibernation will work, or that we are good enough at ecological management (ha!) that we can keep a generation ship viable for centuries. Maybe that will happen, maybe it won’t. Note that as the average lifetime has risen, so has the incidence of cancers.

    Travelling at high velocities causes problems with collisions with the interstellar medium, or small dust particles in the Zodiacal clouds, or (at extreme velocities), highly blueshifted microwave background radiation. As for wormholes and their ilk, these may be too difficult to build (energy requirements, instability, non-traversability etc.), still less transporting one end across interstellar distances.

    Singularity is naive extrapolation. It’s like the predictions we would have steamships going across the Atlantic in mere hours by now (they’d have to have exotic hull materials to cope with the friction). That kind of extrapolation doesn’t work, and the fact that the debate is so hung up on Singularity being the only possible future for a technological civilisation is both unimaginative and unrealistic.

    While this view is unpopular to the point of blasphemy in the futurist/transhumanist cults, it is perfectly possible that the Singularity idea is wrong, interstellar travel is massively impracticable, and that intelligent life gets out of its home star system in only vanishingly rare circumstances.

    Remove the Singularity, and you remove the need for Earth being a singularity in terms of how far biological evolution has come.

  • Brian Wang August 29, 2007, 18:03

    In the full paper, do they talk about powering the beam ?

    In the abstract that I see they talk about 10**20 joules for 10% of lightspeed for a 1000 ton ship. Going 1% of lightspeed would take 100 times less energy 10**18 joules.

    A typical 1200 MW nuclear power plant produces 32 PJ per annum.
    3.2 * 10**16 joules.

    10 twin reactors would get us up to 6.4*10**17 joules. About the power levels need for the 1% of lightspeed.

    how fast and long is the acceleration ?

    Are they looking at a different kind of nuclear reactor ? Some kind of gas reactor where temperatures go a lot higher and the rate of energy production is higher ? Something safer than the nuclear thermal salt water rocket as a reactor ?

  • Administrator August 29, 2007, 19:36

    Brian, here’s a clip from the paper re power requirements:

    “Power requirements to accelerate the pellet-sheath elements to reach the spacecraft can be calculated. Since the velocity to which the sheaths must be accelerated is only slightly greater than the spacecraft velocity, we can estimate the energy in the compressive units and integrate over velocity to get total energy. The total energy to accelerate the units is 9 × 1021 J. The power required can also be evaluated, and this results in an average accelerating power requirements of approximately 1.005 × 1015 W, or 1000 TW.”

    Also note this: “While speculative, one can presume that coupling efficiencies will be high, [above] 80%, and that at 300 g acceleration, even accelerating the pellet element to .1 c will only require a distance of about 1 AU.”

  • Brian Wang August 29, 2007, 19:59

    I am little unclear on the pellet-sheath acceleration power requirement of 1000TW and then two paragraphs down they talk about 2.5TW needed for a laser beam to the pellet/microsails.

    Scaling this to 1% of the speed of light instead of 10% would reduce requirements by a factor of 100.

    10TW for pellet sheath acceleration and 25GW for the laser. also reducing weight from 1000t to 100t
    would drop it to
    1TW for pellet sheath acceleration and 2.5 GW for the laser (probably laser array).

    Dropping it to 10 tons (using MEMS and nanotech)
    100GW for pellet sheath and 250MW for the laser.

    Want to bring the all the system requirements down to something that could be achieved in 10-15 years if we were suitably motivated.

    Not sure if mirrors reflections and lasers would help or if we do that we end up skipping on the whole minimag concept.

  • brian wang August 29, 2007, 21:42

    I have reread the paper again.

    It seems like there is an error on page 455.
    Where it talks about the power required based on 40% efficiency.
    They indicate 2.5 TW when they should be saying 2.5 PW.
    They had 1000 TW (1PW) as the acceleration power needed. So 40% efficiency means 2.5 PW.

    It seems we can make this more efficient by lightening the sheath.
    The pellet is only 80 grams. The sheath is 2kg of conducting mylar.

    If we put some engineering into the sheath (say using carbon nanotubes for strength, conduction and lower weight) maybe we can get the sheath down to 128 grams. A total reduction in weight of the sheath pellet to 208 grams instead of 2080 grams.

    Then the acceleration power for the sheath pellets would go down to 100TW, efficiency could be increased slightly with higher acceleration tolerance and less laser losses. But keeping it at 40%. 250TW.

    Then drop in speed to 1% of lightspeed and the drop in weight of the vehicle would still save 1000-10,000 times

  • Adam August 30, 2007, 2:59

    Hi Brian

    If you want to piddle around the Galaxy at 0.01c you’re welcome to it ;-)

    But for me I’d much rather ramp the sucker up to get the full 0.15c – only 40 years to Barnard’s. Well a bit longer while deccelerating.

    Got to figure out a way of improving the efficiency of the mag-sail though. The decceleration time they quote is painful.

  • george scaglione August 30, 2007, 9:34

    adam,yes we must find ways to explore space much faster than anything we readily envision today! unfortunately breakthroughs WILL be needed! i can think of two or three right off hand but won’t mention them here and now for fear of repeating myself yet again! don’t wish to preach too much about my favorites and i think that by now all our members would recognize the concepts anyway! but,breakthroughs will be needed.thank you very much, your friend george

  • Goldenship9 August 30, 2007, 10:29

    Interesting article

  • Goldenship9 August 30, 2007, 10:30

    That is why the ISS is a good test of technological cooperation in Space.
    Anything of significant size would have to be assembled in Space. Anything wanting to go any significant distance (safely) will need to be able to dock at bases on the Moon or Mars –
    Once we go beyond rocket mentality
    Once we start thinking of spaceships ‘bigger’ than the shuttles, that can carry a larger crew (and resouces for long term space travel) it really starts getting interesting. How to displace them, how to shield them – and ultimately how to reach faster speeds – will follow once we specify the goals

  • Brian Wang August 30, 2007, 12:47

    They were talking about the minimag as being something that could not be as easily weaponized as good old fashioned Orion’s.

    Using ye old impact calculator, for something about 1000 tons

    If it turned around it would hit with 251 megatons of force going at 1% of lightspeed.

    Going at 10% of lightspeed it would hit something with 25,000 megatons of force.

    Also, the GW to TW to PW laser arrays would be pretty threatening too (especially relative to a few thousand measily 100-1000 ton explosions.)

    If you are cruising around the solar system at high speed then you are powerful no matter what. In which case crank this up to critical explosion levels and just figure out how to get the maximum performance out of it.

    I think the minimag could get a configuration where we use rapid subcritical explosions to launch from the ground. And then crank it up to critical explosions once we clear the atmosphere.

    Fusion powered version of Orion could get to 1 million ISP. The more advanced levels of Gabriel (Nasa re-examination of Orion)
    1. Mark I: Solid pusher plate and conventional shock absorbers (small size)
    2. Mark II: Electromagnetic coupling incorporated into the plate and shocks (medium size)
    3. Mark III: Pusher plate extensions such as canopy, segments, cables (large size)
    4. Mark IV: External pulse unit driver such as laser, antimatter, etc. (large size)

    The Mark II starts getting the electromagnetic coupling that minimag Orion has.

    ==I also had an idea that we could start firing sheath/pellets out in front of the minimag Orion before we launched minimag. Then the minimag could scoop up slower moving pellets as they caught up to them on their flight path. We could use a less powerful laser accelerator or let minimag climb to higher speeds than we can accelerate the pellets. Again toughening up the sheath/pellets with carbon nanotubes would let you scoop up slower moving sheath/pellets with a greater difference in speed.

    Laying out pellet streams for our pacman minimag Orion or fullblown Orion would be a boost to any one of the Orion concepts.

  • Brian Wang August 30, 2007, 13:57

    I wrote up my pellet bread crumb concept


    I wanted to get rid of the need for a laser array that uses 2500 times the electrical power that is currently generated in the USA. Needing a monster laser array and mass production of 250,000 nuclear power plants seemed to be something that would delay getting the interstellar ship ready.

  • Adam August 31, 2007, 7:57

    Hi Brian

    Good points. Any high acceleration vehicle makes a brilliant kinetic weapon too. But the Mini-Mag only does 0.42 gee. In a solar system worried about defense a set of rapid fire rail-guns would be sufficient to turn any incoming kiloton mass missile into vapour by spreading a “wall of steel” in its flight-path – high-speed missiles are as maneuverable as a battleship being towed sideways through mud.

    Rapid deployment dust clouds would be enough to trash any laser-sail beams a hostile might want to send Earth-wards. Speed is deadly – to target and to missile. Paul Gilster, chief Centauri Dreamer, has expressed scepticism about an Inner Planet fly-by by a 0.1 c “Daedalus” class vehicle because of the Zodiacal dust, and I must admit the problem isn’t an easy one. The zodiacal dust averages about 100 microns across and thus masses about 1E-9 kg per grain. Interior to 1 Au there’s about 10^16 kg of it – thus about 10^25 grains. A transit vertically through the disk encounters about 141 grains per square metre, thus a total energy flux of 133 MJ per sq.m. Since the disk is about 0.1 AU thick the traverse time is about 500 seconds, thus each forward sq. m. of vehicle is heated at about 267 kW – about 1470 K at equilibrium. The beryllium engine bells of “Daedalus” could withstand that during over 3 years of boosting so heat-wise there’s no great danger.

    But 0.1c means an individual particle energy of about 5 MeV. I’m not sure how well that would thermalise in a few centimetres of beryllium. It’s quite transparent to energetic ions due to its low Z number. Would the vehicle’s interior be fried by sprays of 5 MeV ions?

    I think the main issue is that the acceleration track for boosting a vehicle to 0.1c is so long in solar system scales – 0.1c needs 750 AU at 0.4 gee. Even 0.01c needs 7.5 AU which is most definitely not a reasonable range to fire ballistic weapons over and expect them to survive. Imagine shrouding the Earth in an orbital cloud of dust sufficient to vaporise any 1000 ton 0.1c incoming missile – assuming 3500 K vaporisation temp and about 1,000 J per kg heat capacity, that’s a total flux of 3.5 terajoules. At 0.1c that needs about 4 grams of dust. Assuming a cross-section 50 metres wide the flux per sq.metre is about 2,000 1E-9 kg dust grains. Assume Earth is surrounded out to its Hill Sphere – about 1,000,000 km. Total number: 2.5E+22 – or about 25 billion tons of space dust. Even if the attackers fired a 1,000 ton slug of high-density metal (U238 at 19,500 kg/m^3) the areal density of the dust shield would only need to be 30 times higher to hit the slug with the same energy dose. And of course the energy absorbed by the would be missile goes up with the square of its velocity. Relativistic missiles wouldn’t stand a chance.

    If we used some kind of electromagnetic field to attract natural zodiacal dust – which probably already has a static charge – then we wouldn’t have to launch any shield mass at all.

    Wow. A potential solution to the Zebrowski/Pellegrino dilemma in their “The Killing Star”. When relativistic “vehicles” become viable so too their perfect nemesis.

  • Ronald August 31, 2007, 8:42

    What this all makes very clear to me, or rather confirms, as I have stated in previous posts is: that most likely the first generation of interstellar spacecraft will be miniaturized unmanned robot probes, propelled largely or entirely by (nuclear fusion powered) laser.

    The reasons for this being that unmanned can indeed be kept very small, hence light weight, requiring only a tiny fraction of the energy of any (even hibernated) manned craft and with laser propulsion the engine and fuel can (largely) be left at home. Breaking at destination was the remaining challenge, but apparently the mag sail can take care of that.
    And the lighter the craft, the smaller the mag sail can be, and/or the later the deceleration.

  • Ronald August 31, 2007, 11:29

    I once did a back-of-the-envelope estimate of the amount of energy needed to propell a space probe of 1 metric ton (1000 kg) to 0.1 c at 50% efficiency: it would take 0.03 TeraWattYear (TWY) or (only) about 0.2% of present-day global energy consumption of 15 TWY. This does not take into account the deceleration.

    A laser installation on the moon could keep spitting them out, with only (very) high initial construction cost but very low cost per additional probe.
    And, obviously, as miniaturization progresses, energy requirements decline correspondingly (i.e. 1/10th of the weight –> 1/10th amount of energy), but of course squares with increasing speed (0.5 c would require 25 times as much energy).

    This is also why I believe mastering nuclear fusion will be an absolute imperative for a truly space faring (i.e. galactic, is that level 2 or 3?) civilization: the energy content of all out recoverable fossil fuels (according to the BP statistical review, probably even a bit optimistic) amounts to some 36 ZetaJoule or 1140 TWY (about 75 years of global consumption at constant 2005 level, i.e. much less at presently increasing consumption levels).

    In other words, when dispatching even small interstellar robot probes we’ll be using up our fossil energy resources fast, not even to mention sending a human mission:

    – Suppose we send some 30 of the above light-weight robot probes of 1000 kg per piece to each candidate planetary system (not a lot for a thorough exploration) at an average velocity of 0.3 c (from 0.1 c for the next door neighbors, such as AC, up to 0.5 c for the farther away targets), this would imply 0.27 TWY per probe, amounting to about 8 TWY of invested energy per solar system. Considering this is only about half of humankinds present annual energy consumption, this is not overdone for prospecting the potentially next piece of real estate.

    – This way, however, we’ll be clean through all our fossil fuel reserves by the time we have explored between 100 and 150 systems, not even counting our other daily energy consumption.

    – Nuclear fission, using uranium would only extend this a little bit further: the estimates for exploitable uranium reserves vary greatly, from hardly 500 to well over 2000 TWY, i.e. roughly enough for robotic exploration of another 60 to 300 planetary systems (at 30 probes each), not an exaggeration for an aspiring galactic civilization. Only using fast breeder reactors, with all their risks involved, could we add a substantial 75,000 TWY, sufficient for almost ten thousand of these planetary system explorations (at 30 probes each).

    – But once we find a suitable next home and decide to send humans there, things get really demanding, especially because we do not want them to take forever: sending even a one thousand ton ship at 0.3 c, or a ten thousand ton ship at 0.1 c, would require some 300 TWY.
    In other words, using all fossil fuels and uranium would only allow us to send about 10 of these manned missions (not even discounting what we already spent on unmanned exploration and our other energy needs).
    Even using breeder reactors, we could not dispatch more than some 250 manned missions (ignoring any other energy use), not negligible, but not an exodus either.
    And in case of a ten thousand ton ship at 0.3 c, this becomes resp. 1 and 25 manned missions.

    – The Helium-3 reserves in the outer layers (down to 3 atmosphere pressure) of Saturn and Uranus are estimated at some 3 billion TWY each !!!
    Even when becoming true interstellar gas guzzlers, dispatching say 10,000 robotic probes and 10 manned missions (of the larger kind: ten thousand ton ships at 0.3 c) per year, totalling some 32700 TWY, this would still amount to next to nothing: about 1 / two hundred thousandth of the energy reserve of the outer layers of the two mentioned giant planets.

  • Brian Wang August 31, 2007, 12:32

    I had updated my article on pellet bread crumbs with Lorentz force propulsion of the pellets. Therefore no big laser array needed for pellet deployment. Just some capabilities and economies that are developable from 2012-2020. Super cheap carbon nanotubes are coming. Micro electronic capabilities continue to advance.

    Even though by my estimation we could make an nuclear interstellar probe (even a manned one) leveraging the movement of small objects with propellantless force with near term technology, I believe we should first build up from the asteroid belt and closer (maybe some stuff to Jupiter and its moons and Saturns moons) Jupiter has the big 20,000 times stronger magnetic field for sending out the lorentz force nanovehicles.

    1. Make a cheap means to get to orbit
    2. Build up orbit, moon, Mars and asteroids
    3. Build massive telescope arrays
    4. send unmanned probes for interesting science and investigation
    5. Build up Dyson shell infrastructure (solar power) and mass produce fission and fusion power, increase civilization power budget 1 million to 1 trillion times. Then we know where we want to send stuff and people (based on the telescope recon) and we can easily afford to do so.

  • Brian Wang August 31, 2007, 18:08

    Adam, It is not the high acceleration that is the problem. Once I have sufficient speed and acceleration and ISP (fuel economy) to move freely about the solarsystem, not only can I use the vehicle as a weapon, I can also glide on over the a near earth asteroid and guide it to the destination of my choice. The space capable attacker has the advantage over the less space capable defender and beyond a certain level of capability the one with the space initiative has an advantage. There are a quadrillion big rocks in the solar system. A space capable entity can go hide and start pushing on one of those rocks for months/years and you would have to be a lot better technically than I am to detect and stop/deflect my rock in time. Just hitting and destroying an incoming rock is not enough, the kinetic energy would still be in the pieces. Deflection is also tough and is tougher for the defender. It is easier to start an avalanche than it is to deflect it later on in the process.

  • Adam August 31, 2007, 19:36

    Hi Brian

    I’d like to see an invisible orbital perturbation of a charted asteroid, that’d be quite a trick. Automated telescopes and/or LIDAR would be watching all the known objects in the System periodically. Any propulsion system capable of shoving asteroids would be rather visible, and any beamed energy asteroid deflector’s power source wouldn’t be easy to hide.

    Face it – there’s no such thing as a sneak attack with asteroids.

  • Adam August 31, 2007, 19:44

    BTW a quadrillion big rocks would’ve been noticed by now. Assuming your “big rock” is 200 metres across and has a density of 2,000 kg/m^3 you’re looking at ~1.25E+25 kg of mass… more than twice Earth’s mass. There’s not that much mass in the Main Belt, the Jupiter/Neptune Trojans and the Kuiper Belt combined.

  • Adam September 1, 2007, 7:04

    Hi All

    Ronald, there’s quite a bit of fission fuel available especially if breeder reactors are used and burn U238 & Th232. I’ve read that there’s at least 100 million tons available in North America alone. Sure the mine tailings would cover a couple of states, but it’s there and extractable. I’ll dig up the reference if you’re interested.

    But you’re right about fusion power being the preferred option for starships, unless self-replicating solar powersats become viable. Concentrators and 50% efficient PVs can make ultra-light powersat complexes – about 1,000 tons for about 3 GW in-space power. That might be enough to launch laser-sail pellets at a starship using multiple reflections. I’m yet to figure out the maths on multi-reflection laser-sails, so I’m not sure. Check out Brian Wang’s posts on the idea. Anyway a starship powersat complex would be immense. Fusion might be way easier.

  • Ronald September 2, 2007, 3:28


    yes, I forgot to mention solar power. You are absolutely rright that there is plenty of it available (the sun emits the same amount of energy per second as humankind consumes in 800 years, at approx. 2005 consumption level), however: the problem is rather the low power density, as you indirectly mention. 1000 tons for 3 GW (and that is even called ultralight) is still a lot of matter and not much power for interstellar travel, if we are to use laser propulsion. We’ll need a lot of GW or even TW. Indeed you’d need

    I cannot really judge Brian Wang’s idea of the pellet shooting and scooping, but it seems a bit complicated. How reliable would it be (I mean not missing the pellets) and how (un)vaforable are the nergetics?

    Breeder reactors: yes, possible, but more complex and riskier than ‘normal’ uranium reactors, lots of plutonium and nuclear tailings.

  • Adam September 2, 2007, 6:52

    Hi Ronald

    Sunpower is more effective if the collectors are closer to the source – if the laser batteries are parked at 0.1 AU the power density of the collectors goes up to 300 GW for 1,000 ton mass. That’s 300 kW per kg which is incredible. A 2 ton starprobe can be launched via Jordin Kare’s SailBeam system with a 100 GW laser, so extrapolate from there for the uranium pellet launcher Andrews proposes.

    For the power levels required to launch starships, fission reactors will of necessity be fast neutron reactors. Imagine a giant gas-core rocket with an MHD generator attached – that’s the kind of system required. Being gas core it can ONLY be a fast-neutron reaction cycle, thus it will have a very high burn-up fraction.

    I should have said “fast neutron” instead of “breeder” – the best example is the Integral Fast Reactor which was run for about a decade before being shutdown under Clinton. Fast reactors can burn a mix of plain old uranium plus a bit of seed plutonium, and their fuel mix is virtually impossible to extract high purity plutonium from for weapons. What’s unattractive about Fast Reactors, from a government point of view, is they would make the mining of uranium redundant for decades because all the stockpiles of “waste” could be used as fuel in Fast reactors. And governments can’t collect taxes on waste disposal.

    Yet the best thing is that same fact – the same energy can be extracted via mining a much smaller amount of uranium. Consider: enriched uranium reactors need uranium enhanced from the natural level of 0.7% U235 to about 5% U235. And only about 3% is actually used before the remainder becomes “waste”, so for the same energy produced fast reactors burn only 1/30th of the uranium. And what waste they make is fast decaying fission products that only need a few decades of safe storage instead of 10,000 or so.

    Of course no one tells politicians such inconvenient facts. My country’s government has plans of collecting billions in uranium royalties and probable plans to build a high-grade waste facility so other countries can dispose safely, for a good price no doubt. We’d collect money at both ends of the fuel cycle.

  • Darnell Clayton September 3, 2007, 22:23

    Despite being late to the game (of this post) this is exciting news indeed!

    Although before we begin to conquer the galaxy, I suggest we “beta test” it with our own solar system first, preferable the outer gas giants.

  • Adam September 4, 2007, 0:37

    Hi Darnell

    What do you mean by testing Mini-Mag Orion amongst the gas giants? Exploration missions to Neptune? Or do you have something else more elaborate in mind? Certainly what can get to the stars can fairly easily get to the outer planets – at least for a flyby, but since Andrews et. al. were using an electromagnetic deccelerator it might be really hard to stop such short-range missions. Might make a fantastic commuter system if we set up beam complexes at both ends, but in that case something like Robert Winglee’s Mag-Beam would be better suited.

    Of course Mini-Mag Orion can carry its own pulse charges, but that wouldn’t be a full system test then.

  • Darnell Clayton September 6, 2007, 15:51

    Hey Adam!

    Basically I was saying that it would be great to test this first around our own gas giants, although stopping might be a problem.

    Speaking of interstellar travel, since 10% light speed is probably the best we are able to do (at least within our horizon) we might want to see if there are any habitable worlds orbiting the star system before sending world ships…as it would be sad if we sent crews towards a star that had no or uninhabitable planets.

  • Adam September 6, 2007, 18:46

    Hi Darnell

    By the time we have the in-space assets to send starships we’ll definitely have at least crude maps of the target planets, if not results from high-speed micro-probes. We’ll know quite a bit about the destination before we set out. But even if habitable planets are rare, the building of a WorldShip would allow us to replicate such in the target system from whatever free-space mass is available. A proper WorldShip will be like a macro-organism, thus able to self-replicate. Advances in rapid-prototyping and on-demand manufacturing will mean that the means will be available to the WorldShip to make anew anything they need. Centuries of voyage time require a system able to repair and rebuild itself, especially on arrival.

  • Ronald September 7, 2007, 5:51

    Hi Darnell, maybe an open door, but undoubtedly the Alpha Centauri system will be one of the very first targets for planet detection and maping, visual I mean (imaging).
    And we are almost able to do just that: even SIM, the Space Interferometry Mission, a kind of try-out for the real things, such as TPF, will be able to detect, image and spectroscopically analyze earth-sized planets in the AC system. And with advances in adaptive optics I wouldn’t even be surprised is, in the near future, groud-based (optical) telescopes will also be able to do that.
    I bet that within 5-10 years orso we’ll know quite a bit about any planets near AC.

  • Nick September 20, 2007, 23:24

    Ever thought of living in the here and now? Seriously! Listen to yourselves.

  • Malcolm Ramsay September 21, 2007, 13:14

    But where is here and when is now, Nick? We live on Earth, a planet that interacts continuously with a vast and still poorly understood universe; the past is gone and the present lasts only the smallest amount of time possible. The entirety of space and of the future are the only things that we can think about, so to ignore them for an essentially fictitious “here and now” is to limit one’s view to the ultimate extent.

    We are the one’s looking for the solutions to today’s problems; what are you doing?

  • ljk February 15, 2008, 23:31

    To Mars by A-Bomb

    The Secret History of Project Orion


  • James M. Essig February 17, 2008, 16:01

    Hi ljk;

    It is interesting to note that a revamped Project Orion might just enable manned travel to the nearest stars possible via a nuclear bomb pulsed thrusting mechanism. Today’s nuclear warheads have a much higher yield per warhead mass than the warheads of the 1950s and thus would yield a higher effective specific impulse. Pure fusion devices simmilar to those allegedly being studied by the U.S. military/nuclear weapons research complex would be good for peaceful purposes for propelling starships to perhaps 0.1 C to 0.3 C +. I could not think of a better use for such devices.


    Your Friend Jim

  • george scaglione February 19, 2008, 9:05

    jim you are 100% correct in your surmises for the “use of nuclear weapons” above…but is not that sort of thing strictly forbidden??! anyway,even if it is,one can dream! if you know much more about the current status of this subject i hope you can tell us! hope we talk about it again soon,your friend george

  • zam July 30, 2008, 18:36

    I think I know now how Leonardo Da Vinci felt about winged flight while trapped in the 15th century. We, today, when it comes to all the theories of interstellar spaceflight, seem trapped in the 21st century.
    I agree with the posts that state that we will indeed need breakthroughs in physics before practical interstellar flight becomes possible, if ever. There’s no sense in wasting our time on flapping wing aircraft and Da Vinci ‘whirlybirds’, as Nuclear starships and other concepts seem analagous to.
    If we ever find a Grand Unified Theory of Everything then maybe we’ll then discover and apply anti-gravity and warp drives, and who knows what. Maybe Roddenberry’s fiction wasn’t that far off the mark in terms of timeline. The twenty-third or 24th century is probably accurate.
    But I certainly would’nt want any of you wonderful guys to stop tinkering around with the engine/propulsion design concepts! Otherwise that 23rd century scenario will never happen.

  • MJ DeYoung November 9, 2008, 6:47


    Super DaVinci analogy, depressing but good. I agree, (minus some unexpected near term breakthrough) we will unfortunately have to patiently and steadily continue scientific inquiries and research until we arrive at our goal. Perhaps its for the better, can any of you guys imagine the mess we would likely make we were suddenly able to stumble and bumble en mass into other star systems at our current level of scientific and spiritual sophistication. Think alien viruses, bacteria, and God knows what else.

  • ljk November 24, 2008, 0:13

    To Mars by A-Bomb – The Secret History of Project Orion (BBC).

    The extraordinary yet true account of a secret US government-backed attempt to build a spaceship the size of an ocean liner and send it to Mars, Jupiter and Saturn, propelled by thousands of miniature nuclear bombs.

    Beginning in 1958 Project Orion ran until 1965, employing some of the best scientists in the world, including the brilliant British mathematician and physicist Freeman Dyson.

    “Freeman Dyson is one of the few authentic geniuses I’ve ever met”, says Arthur C. Clarke. “Orion isn’t crazy. It would work. The question isn’t whether we could do it, but whether we should do it”.

    Full article here:


  • ljk December 4, 2008, 10:24

    Deuterium microbomb rocket propulsion

    Authors: Friedwardt Winterberg

    (Submitted on 2 Dec 2008)

    Abstract: Large scale manned space flight within the solar system is still confronted with the solution of two problems: 1. A propulsion system to transport large payloads with short transit times between different planetary orbits. 2. A cost effective lifting of large payloads into earth orbit.

    For the solution of the first problem a deuterium fusion bomb propulsion system is proposed where a thermonuclear detonation wave is ignited in a small cylindrical assembly of deuterium with a gigavolt-multimegampere proton beam, drawn from the magnetically insulated spacecraft acting in the ultrahigh vacuum of space as a gigavolt capacitor.

    For the solution of the second problem, the ignition is done by argon ion lasers driven by high explosives, with the lasers destroyed in the fusion explosion and becoming part of the exhaust.

    Comments: 12 pages, 4 figures

    Subjects: General Physics (physics.gen-ph); Plasma Physics (physics.plasm-ph)

    Cite as: arXiv:0812.0397v1 [physics.gen-ph]

    Submission history

    From: Friedwardt Winterberg [view email]

    [v1] Tue, 2 Dec 2008 00:20:42 GMT (291kb,X)


  • ljk December 4, 2008, 10:26

    Ignition of a deuterium micro-detonation with a gigavolt super marx generator

    Authors: Friedwardt Winterberg

    (Submitted on 1 Dec 2008)

    Abstract: The Centurion-Halite experiment demonstrated the feasibility of igniting a deuterium-tritium micro-explosion with an energy of not more than a few megajoule, and the Mike test, the feasibility of a pure deuterium explosion with an energy of more than 10^6 megajoule.

    In both cases the ignition energy was supplied by a fission bomb explosive. While an energy of a few megajoule, to be released in the time required of less than 10^-9 sec, can be supplied by lasers and intense particle beams, this is not enough to ignite a pure deuterium explosion. Because the deuterium-tritium reaction depends on the availability of lithium, the non-fusion ignition of a pure deuterium fusion reaction would be highly desirable.

    It is shown that this goal can conceivably be reached with a “Super Marx Generator”, where a large number of “ordinary” Marx generators charge (magnetically insulated) fast high voltage capacitors of a second stage Marx generator, called a “Super Marx Generator”, ultimately reaching gigavolt potentials with an energy output of 100 megajoule.

    An intense 10^7 Ampere-GeV proton beam drawn from a “Super Marx Generator” can ignite a deuterium thermonuclear detonation wave in a compressed deuterium cylinder, where the strong magnetic field of the proton beam entraps the charged fusion reaction products inside the cylinder.

    In solving the stand-off problem, the stiffness of a GeV proton beam permits to place the deuterium target at a comparatively large distance from the wall of a cavity confining the deuterium micro-explosion.

    Comments: 14 pages, 7 figures

    Subjects: General Physics (physics.gen-ph); Plasma Physics (physics.plasm-ph)

    Cite as: arXiv:0812.0394v1 [physics.gen-ph]

    Submission history

    From: Friedwardt Winterberg [view email]

    [v1] Mon, 1 Dec 2008 23:59:52 GMT (968kb,X)


  • John July 26, 2009, 9:41

    I think that dismissing the much-more-easily achieved 0.01G starship is a mistake. The important thing is to START.

    Question: What are the barriers to the 0.01 starship? Answer: there are no technological barriers, only industrial, financial and political. And the first two categories are instantly solvable once the third category is solved.

    Question: Can we find volunteers to crew it? Answer: Of course. Stop thinking about the ship YOU want to travel on because YOU are never going to go: you are too old, too fat, or unqualified, or just born at the wrong time. Ask only this: will our species be able to build it, NOW, if it chooses, get it crewed and sent on its way? Yes. Absolutely.

    That’s all. Stop talking. Get started.