Giant Slingshot: New Way to Space?

All space projects get into orbit pretty much the same way by burning lots of rocket fuel, a spaceship powers itself past the sky. But what if there was a different approach? What if we could throw something so hard, it would wind up in space? At NASA’s behest, Ed Schmidt and Mark Bundy of the Army Research Lab are looking at ways of firing projectiles into orbit.
slingatron2.JPGThe notion has a very long pedigree. Back in 1687 when Isaac Newton first came up with the theory of gravity he also introduced the concept of an orbital cannon which could fire a cannonball so fast that it would never come down. The first serious attempt to shoot into space was the High Altitude Research Program (HARP)
carried out in the US in the 60s (not to be confused with HAARP High Frequency Active Auroral Research Program so beloved of the tinfoil hat brigade). HARP used a modified 16-inch naval gun to loft projectiles to the incredible altitude of 112 miles before being cancelled in 1967.
The ARL study looks at more sophisticated approaches than your basic cannon, including a blast wave accelerator, and electro-magnetic rail gun, and an EM coil gun. But the wildest idea may be the Slingatron: a giant, hypervelocity, rapid-fire slingshot. The machine would spin a projectile faster and faster through a spiral-shaped tube, building up increasing amounts of centripetal force along the way just like a discus-thrower, spinning himself around before a toss, or like a latter-day King David, winding up his weapon before he whacks Goliath.
Schmidt and Bundy are cautiously positive about Slingatron and the other launch concepts:

– Achieving an 8 km/s muzzle velocity did not violate any laws of physics
– All had serious engineering and materials issues
– Significant research is required
– Facilitization costs would be high
– All are high risk

So its a big project which will take some development, but the benefits would be phenomenal. If we can spend $7 billion+ on an airborne laser which is frankly unimpressive, why not put a billion into each of these concepts – then use the rest to build whichever looks best?
An orbital launcher would bring the cost of putting a payload into orbit from around $10,000 a pound to a few hundred dollars. (The G-forces are so huge, astronauts still have to go up the hard way). The main problem as far as I can see would be fights breaking out in the queue to use it. [OK, not exactly. But Hambling’s on a roll here. Let him go with it. — ed.]
NASA wants it to send up components of the ISS or future lunar of Mars missions. Send up the pieces and it could all be assembled in Earth orbit before moving on go where no man has gone before. Or they could use it as a first-stage, putting rockets into orbit which could then boost small probes to the rest of the solar system.
HARP.jpgOr it could be used to put up new nano-satellites by the score, at short notice and without the need for scarce and expensive rockets.
But for the Pentagon it could be a candidate for the ideal Global Strike tool: capable delivering a one-ton bunker-busting tungsten supercavitating penetrator at orbital speed. [Not that we’re encouraging this sort of thing.] Thats real Shock & Awe, which could arrive anywhere in the world with no warning before bombers could get off the runway. (Anyone remember Saddam Husseins Project Babylon Supergun , or the Nazis V3 plans?)
Alternatively, an aeroballistic pod could be launched which would break open at high altitude to release a dozen Dominators or similar craft to find and attack precision targets, catching fleeing terrorists in less time than it takes to get a Predator into the area.
Then again, the anti-satellite people might want to have a go too. [Not that we’re looking to encourage them, either.] It would make a neat anti-aircraft gun, firing small guided projectiles, and might offer some interesting options for kinetic ballistic missile defense.
Maybe SOCOM might want a look for about instant re-supply anywhere, for when it absolutely, positively has to be there within the hour, regardless of weather conditions?
If you take a look at my book Weapons Grade, youll find a chapter with an unusual history of the Space Race. It shows how the space program for both East and West originated with the German military V-2 program, and progressed on the back of post-war ballistic missile programs. The launchers on both sides were modified versions of rockets originally designed to carry warheads. The idea of space travel had been around for years, but it took military interest to make it happen.
We may now again be in a situation where the next major breakthrough in space technology is just waiting for the military to take the lead again.
The possibilities are endlessbut, I think I hear Monsieur Vernes lawyers at the door, something about stealing his idea of going From The Earth To The Moon
David Hambling
UPDATE 05/10/06 12:23PM: Not only is physicist a fan of the Slingatron, but, apparently, Google co-founder Larry Page is, too.

54 Comments on "Giant Slingshot: New Way to Space?"

  1. I’m unable to post a comment in the prior post, “Rapid Fire.” Are comments disabled for that post?

  2. Start up google.
    Type in: (8 km/sec)^2/(30 km) in g
    That’s right, even for a small facility (30 km!)
    you have to provide 200 g of acceleration on the
    payload on the last cycle JUST TO MAINTAIN ITS
    TRAJECTORY.
    It may not violate laws of physics, but it
    probably violates every law of economics. $100/lb
    to orbit, my ass!

  3. Actually, once it is built, all you use up each shot is electricity.

  4. Noah Shachtman | May 9, 2006 at 8:18 am | Reply

    Fixed, Chris.

  5. Nitpick: You’re not building up centripetal force in the spiral. You’re building up speed.

  6. I worked for the Navy in the early 70s and reviewed the HARP reports. The launcher consisted of two 16 inch gun barrels in tandem and was the brainchild of Dr. Gerald Bull who also was behind Saddam Hussein’s “supergun”. He was assinated outside his apartment in Brussels probably by the Mossad.

  7. Noah Shachtman | May 9, 2006 at 10:57 am | Reply

    I sat through a briefing on [Slingatron] a while ago,” a source writes in. “It was funny, first it started out with an overhead projector with badly drawn concept + math, then it moved to a powerpoint briefing then onto a fullblown 3d cad mockup. I was worried as an encore they were going to wheel out a real one. In the end, though, the physical forces on the slingatrom were huge and would require ‘major breakthroughs’ in material science.”

  8. Allen Thomson | May 9, 2006 at 11:18 am | Reply

    Back in SDI days, livermore had an orbital light gas gun project called SHARP http://www.astronautix.com/lvs/sharp.htm
    Although the prototypes that got built used conventional energy sources, the ultimate idea was to use a pebble-bed reactor to get the hydrogen working fluid really, really hot. Nuclear cannons to orbit!

  9. David Hambling | May 9, 2006 at 12:08 pm | Reply

    Well, CERN’s LHC is 27 kilometres in diameter and seem to be a pretty effective way of accelerating things to extreme speed. It’s not cheap, but once it’s built it’s a world-beater.
    Perhaps an orbital launcher could be hired out as a particle accelerator during slack periods..if there are any…

  10. The LHC is accelerating sub-microscopic,
    electrically charged objects. And still costs
    billions.
    That alone should show how ludicrous this idea
    is.
    Completely off-topic, but does anyone know if
    the mid-course missile defense project has an
    anti-satellite capability? I’m sure they don’t
    want to talk about it, but if you think about
    it, it already has everything you would need,
    since ICBMs fly higher than low flying
    satellites …

  11. Jordin Kare | May 9, 2006 at 2:57 pm | Reply

    Allen Thomson: Back in SDI days, livermore had an orbital light gas gun project called SHARP… the ultimate idea was to use a pebble-bed reactor to get the hydrogen working fluid really, really hot. Nuclear cannons to orbit!
    As a long-time colleague of John Hunter (who built SHARP), I don’t believe he’s ever planned to use a nuclear reactor for gas gun power. His larger designs use an entirely non-nuclear pebble bed heat exchanger, preheated by, typically, natural gas flames, to transfer a large quantity of heat to hydrogen very quickly. Pebble beds have large surface area/volume, low flow resistance, and can easily tolerate high temperatures and thermal shock, which makes them good for reactors, but also good for many non-nuclear uses.
    John has continued to develop the light gas gun launcher since leaving LLNL, and has a small company, JVL, LLC that works on gas gun technology. JVL is short for Jules Verne Launcher.
    The Slingatron has been around for many years; it was in fact invented by a particle physicist as a mechanical version of a particle accelerator. It has advantages and disadvantages relative to other “cannon” launchers, but shares with them the need to have an onboard rocket stage to circularize the projectile orbit. That almost always makes the real marginal cost of payload to orbit for cannon launchers well over $100/lb.

  12. Robert Carnegie | May 9, 2006 at 3:41 pm | Reply

    LHC pushes things to the speed of light, as good as; to the point where they aren’t going faster, they’re just getting heavier and heavier.
    That’s rather more than is required for an orbital cannon. Escape velocity is /way/ less than c.
    Rockets are damn expensive. Why believe there isn’t a cheaper way up that just hasn’t had the development investment done yet?
    Having said that, I expect the Rise Of The Machines and the destruction of humanity before human space launches really become commonplace. So when we conquer space, we’ll be robots. And we probably won’t launch mass – we’ll build new bodies out of the materials already out there.

  13. Maybe the Slingatron could use Inductrack / Halbach array technology as a frictionless magnetic bearing for motion through the spiral.

  14. Does this not rely on centrifugal, rather than centripetal, force. Can someone clarify?

  15. Maybe I’m not reading this correctly, but this is just a twisted-up rail gun. I don’t really understand what the circular track gets you, except for tremendous lateral loads and perhaps a more-conveniently-sized device.
    Both centripetal and centrifugal “force” are something of a misnomer. What you’re actually talking about is centripetal acceleration. Newton told us that Force=Mass*Acceleration, hence the confusion between forces and accelerations. If you remove the centripetal acceleration, the object doesn’t travel out away from the center of rotation, but tangential to the circular path it was tracing. (See trebuchets)
    Anyhow, I’m not sure I see the point of the circular design, but I’m sure somebody thinks it’s a good idea.

  16. I read a series of books by Frederick Pohl named “Gateway”. in this series, they made use of a slingshot system to make orbit. i always found it to be interesting.
    for anyone interested, the series is fairly easy to read, is completely fun to read, full of lively characters, and can take ideas like string theory and break it down into lay-speak quite easily. i highly recommend them for saturday readings.
    thanks for the information.

  17. Wouldn’t a giant elastic bungee band suffice?
    Think of the cost saving and reuseable value!
    Great for taking pot shots at UFO’S and recreational at theme parks.The ulitamate thrill
    ride.

  18. Actually I think people are misunderstanding how it works.
    It looks as though the projectile is fired into the coil at low velocity probably with a gas gun but as it starts to loop around the coil the actual track itself ~is moved~.
    The coil is tightened and like an ice skater pulling their arms into their body during a spin the projectiles velocity is increased exponentially.
    In theory it would work but as others have stated in the last loop it would require a tremendous amount of energy to continue changing the projectiles trajectory to make it follow the loop rather than shooting out the side of the device.

  19. The spiral would result in a somewhat handier footrpint, one might even manage to stick it on a carriage and thus not be limited in one’s trajectories. For me though, bring on the space elevator. I wanna ride the beanstalk to the GEOHilton before I go…

  20. Centripetal force isn’t a benefit, it’s a drawback. The reason why a coil would be used is simply for space purposes–It is easier and more portable to build a 1000′ cannon shaped as a coil than one shaped as a traditional straight tube. If the coil had a diameter of 200′(still pretty damn big), a one metric ton projectile would require 640,000,000 newtons of force to keep it from blowing out the side of the barrel. To give you an idea of how much force 640,000,000 newtons is, each tower of the Golden Gate bridge holds 548,000,000 newtons. Based on these calculations, I call BS on the whole idea.

  21. Ignoring the energy costs and the G force on the projectile, an object would have to reach high altitude with a remaining velocity of around 5 miles per second. Since re-entering orbital vessels have serious heating problems at high altitude, why wouldn’t the projectile, traveling much faster, not simply burn up shortly after leaving the launcher?

  22. This sounds dumb, but I’m serious…. if we want to lift parts into space, why not do it slowly instead? Use a balloon, or similar, to get the stuff up to thin air/low gravity, then fling it or let a smaller rocket take it from there.
    Like this for instance:
    http://www.outofthecradle.net/archives/2005/12/ascending-into-space-john-powell-talks-about-jp-aerospace-part-two/
    I realize this isn’t useful for flinging bunker busters around… but perhaps it would suffice for more stuff in space.

  23. Ahhhhmmmm, frankly I want to see lots and lots of weapons go into space. A nice space weapon vs. space weapon could develop and if things got to tense stage we would have some time on the ground while who was king of the high ground got sorted out. Just my HO.

  24. Is this the roadrunner/coyote school of rocket science? Just have ACME make it.

  25. As already hinted below, any purely ballistic space launcher must propel a payload through our sea-level atmosphere at velocities of something over 8 km per second, or about Mach 24. This is what is needed to reach any sort of orbit. Even if those velocites could be achieved – and maintained in the face of energy loss to a huge shock wave – any conceivable payload would be incinerated in a few seconds.

  26. This sound something like the paper I resented at the 2005 Mars Society Convention. However my concept for a Circular Electromagnetic Mass Driver. It is a single electromagnetic rail line about 20 miles in diameter. One can use electricity to build up payload speed for as long as one likes, obviating the need for huge accelerations with guns, etc. It would be sunk into bedrock, so that the huge lateral forces could be dealt with. At 100% efficiency, one uses $2.50 worth of electricity per lb. to accelerate mass to 25,000 mph. Preliminary calculations indicate heating would not be a significant problem. Go to http://www.evolutionaryresearch.org/circularmaglev/ to see the paper.

  27. Joseph Hiddink | May 11, 2006 at 11:24 pm | Reply

    Maybe the President could make a speech and urge all Americans to save the rubber bands and send them up to Nasa, which will make thereupon the biggest slingshot in history……

  28. The Slingatron concept was also published in the L5 News in the 1980’s I believe.

  29. Responding briefly to Michael Turner: Unfortunately, you need most of the delta-V for circularization within the first orbit (for launches to low Earth orbit) which rules out electric propulsion. You can minimize the delta-V either by launching close to horizontal (which is very costly in air drag) or by launching to a high apogee, much higher than the desired final orbit (which is expensive in initial velocity). Increasing the exit velocity of any kind of “cannon” launcher tends to be very expensive above 8 km/s, both in the actual launcher cost and in the difficulty of protecting the projectile from atmospheric heating on its way up. The result is that John Hunter and most others who have designed space launch guns have ended up with a relatively low gun velocity and a hefty (sometimes 2-stage) circularization motor. With the motor and associated control system, the projectiles get fairly expensive even if mass produced.
    (And for those who wonder why the Slingatron is a spiral: it’s not just a compact railgun. The whole spiral is mounted on offset pivots and moves in a small circle, accelerating the projectile the way you’d accelerate a marble rolling around inside an upside-down Frisbee. No electromagnetism involved.)

  30. Would it be possible to save energy in the first few moments of flight by building the launcher at a higher elevation? I know the base elevation in the Rockies is between 4000 and 7000ft, and of course the mountains go up to 14000ft. I know that a very significant fraction of the atmosphere lies below these levels. So why not save energy by not having to shoot through the initial thickest layer with the most drag? If you could also build it at elevation closer to the equator, say, in Mexico (some places there are much higher than anywhere in the continental US) you could also benefit from the rotation of the Earth.
    Has anyone considered using a “flying saucer” approach to the payload? The shape would give it aerodynamic lift I presume (not exactly sure how it would work at such high velocities). Manufacturers and project designers would have to adapt to the new dimensions of course. I mean, think of a discus or a frisbee, a spinning disc can go very far with relatively little energy.

  31. Wile E Coyote | July 21, 2006 at 4:07 am | Reply

    I remember this one. It didn’t work out so
    well for me!

  32. 20,000 tons for a .4 meter ID barrel (10" thick per ARL) operating at 9 cycles per second is 40,000,000 pounds accelerating from a dead stop to full acceleration to a dead stop every .055 seconds. Bet they have lots of material issues along with bearing issues.

  33. what if space ship were on a mag level rail system being pushed by that system, and in addition a pulse laser pushing from behind would it make it in to space with out fossil fuels.

  34. If we ever establish a moon base,we may possible go farther in to space, where gravity plays a lesser role on the slingatron

  35. I believe by building a bungee rocket that we can go around a football fields length

  36. WHY NOT CONSTRUCT A CANNON AROUND THE EARTH (40 000km long) with a preogressive acceleration like a train supra conduction , and in the end , by leaving the rail at the appropriate speed (about 1666,6 periodic) goes orbital hahaha…
    or build a gravity detector , like franklin showed how conductivity of electricity worked… i bet it have something to do with v

  37. 100B is not bad once built. Let’s see tests to prove if it will hold on larger payloads and higher speeds.

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