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Magnetic Ring Could Launch Satellites, Weapons
MattSparkes writes, "A new study funded by the US Air Force has suggested a cheaper method of sending satellites (possibly missile weapons) into orbit. A 2-km-wide ring of superconducting magnets would contain and propel a payload, accelerating it over a period of hours, before suddenly flinging the satellite into space at 23 times the speed of sound. The satellites would be engineered to withstand the g-forces encountered (2,000 g), and be cased in an aerodynamic shell. A two-year study has been commisioned and will begin within a few weeks at LaunchPoint Technologies in Goleta, California." New Scientist points out that if such a launch ring were built, it would instantly become "one of the most important targets on the planet."
Am I the only one seeing the parallel?
I'm a fiscal conservative, it's a pity we don't have a political party anymore
Space burials (presumably of cremated remains). At $200 each (plus cremation) I am sure they could sell a few thousand of these per year. Now if they could only figure out a way to allow living people to withstand 2000g of acceleration, space tourism might actually be affordable.
I Am My Own Worst Enemy
that gauss density could be fatal and/or affect instruments.
I know there's a relationship between bird migration and magnetic fields, too, as a lot of them blindly smack into the brick walls at a local MRI center.
A feeling of having made the same mistake before: Deja Foobar
We could fling refrigerators at North Korea! How's that missile testing going, Kim, did we mention we can launch frigidaire's into orbit? I'd prefer launching cows in homage to Monty Python and the Holy Grail, but at 2000g, that would probably equate to throwing hamburger.
"Don't you know you're going to shock the monkey?"- Peter Gabriel
Yes!
As for it being a target, fuck that. Full steam ahead.
If we're not driving payloads into space at Mach 23 within 10 years, the terrorists have already won. Or something.
"New Scientist points out that if such a launch ring were built, it would instantly become "one of the most important targets on the planet.""
I knew lawn darts were dangerous...but god-damn.
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If this ring is going to be "one of the most important targets on the planet", maybe they should build it as a series of concentric rings instead of a single ring. Perhaps havethe rings use alternating colors.
Unknown host pong.
"
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-James Baldwin
Suggestion for the first test: Enter it in next year's Punkin Chunkin' contest!
>> "What would the robut do? Frame someone!"
"I also wonder how much energy it would use to do such a thing compared to the energy expended launching the payload using a conventional solid/liquid fuel rocket."
;-)
I don't know the numbers, but the bulk of a conventional rocket fuel us used up getting the last bit of fuel to near orbit. So the for example, the first 100kg of fuel is used lifting the last 10kg of fuel.
With this ring type of accelerator, there is no basically no fuel onboard to used to enter orbit, so you don't need the resulting mass to accellerate is 100x smaller. Look how big the Saturn 5 was just to lift a basically small payload. Most of the lifting was lifting the fuel to do the lifting.
...then we can play catch.
http://en.wikipedia.org/wiki/M712_Copperhead
Now you're aware...
The world is made by those who show up for the job.
First the FUD:
New Scientist points out that if such a launch ring were built, it would instantly become "one of the most important targets on the planet.
What a moronic comment.
You have a STATIC launcher.
It can toss things into ballistic trajectories.
One at a time.
With a warm-up of TENS OF HOURS.
I don't know if New Scientist realized this, but we have launch technologies that are
a) less vulnerable
b) more accurate
c) mobile
and
d) a little quicker to fire than that.
On another note, and not that this will mollify the crowd that fears a weapon in every technology, but in regards to the difficulty of punching something through the atmosphere at Mach 23, I seem to recall SDI experiments where a high-power laser was used to heat a 'track' through the atmosphere (in that case, to fire a particle beam weapon down the track with less atmospheric attenuation ). Couldn't a similar idea significantly reduce the air resistance for this sort of a projectile?
-Styopa
2000g is the expected angular acceleration.
My
Your lapse is forgivable, but only because the proliferation of terms like "Gauss gun", "rail gun", and "mass driver" in SF has overwhelmed their usage as technical terminology. But the point is, THIS IS NOT A RAIL GUN.
A rail gun is a parallel, non-touching pair of conductive rails, joined at the back-end by a partial circuit capable of generating an extremely high current flow (amps) of electicity in a very, very short time. A conductive projectile is injected into the gap between the rails (so that it touches both rails at once), which completes the circuit. As current flows from one rail to the other, through the projectile, it generates a powerful magnetic field. The Lorentz force causes the projectile to be pushed toward the far end of the rails--the magnitude of the force depends on the current flow.
Rail guns can achieve extremely high velocities, far higher than conventional explosive-charge guns. The velocity of a firearm projectile is limited by the velocity of the expanding explosive gasses that propel it out of the barrel; the gas velocity is in turn limited by the speed of sound in the gas medium, which has a physical upper limit for any type of explosive. Rail guns don't suffer from this limitation.
I have seen references to a 'Gauss gun' which consists of a series of solenoids stationed along a tube barrel, timed to trigger so that a ferrous metal projectile will be pulled faster and faster down the barrel by each of the solenoids in turn. I don't know how valid this terminology is, though.
"My pacemaker!"
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Never been known to fail..."
"When the sled had been accelerated to its top speed of 10 kilometres per second, laser and pyrotechnic devices would be used to separate the cone from the sled. Then, the cone would skid into a side tunnel, losing some speed due to friction with the tunnel's walls. The tunnel would direct the cone to a ramp angled at 30 to the horizon, where the cone would launch towards space at about 8 kilometres per second, or more than 23 times the speed of sound. ... Anything launched in this way would have to be able to survive enormous accelerations - more than 2000 times the acceleration due to gravity (2000g)."
They claim that the payload would be accelerated slowly around the ring. The huge acceleration occurs when the payload's trajectory is changed to angle it up 30 degrees towards the sky. Why wouldn't they angle the ring itself at 30 degrees, releasing the payload at the point where the tangent points up at 30 degrees? They wouldn't need a ramp at all, just a piece that moves out of the way before the payload swings around the loop again.
You mean, like Vandenberg, and Cape Kennedy, and...
Anywhere the capability exists to put a payload into orbit is a target.
That "most important target" bit was a simple piece of scaremongering.
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The laser designator for the Copperheads was quite large, the ones I saw were vehicle mounted. I would imagine that in the 20+ years since I saw them that they've gotten smaller and smarter.
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You forget that it's circular. It's accelerating by changing direction as well as increasing speed.
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That novel did not describe a ring. The electromagnetic launchers in that book were both "simple" linear accelerators. :)
In the launch-ring article, I noticed the air-resistance problem being mentioned, during the initial acceleration phase.
I might suggest this idea as pointing out a solution to that problem.
The article and basic approach remind me of Gerald Bull's work and his disturbing tale of doom as documented on the Doomed Engineers site:
Gerald Bull had a vision and an obsession, a vision that led to estrangement from his native Canada, prison in America, and ultimately assassination by Israel. His vision was of an entirely new way to get into space: small rockets boosted by giant guns. To achieve it he worked for some of the worst regimes on earth: South Africa, China, and ultimately Iraq. His work affected the course of two modern wars and revived the ancient field of artillery.
What about using this thing to shoot water/food/structural materials into space? That is where the savings really come into play. If there is to be a moon base, all the water has to be shipped up there. People need lots of water, so cutting the cost per kilogram to 1% of current levels is a very big deal.
This post climbed Mt. Washington.
Except that the proposed design accelerates the payload around in a circle -- using magnets arranged inside a torus -- not a long straight runway. I doubt a linear runway would be practical; it would just be too long. The advantage of a torus is you can keep using the same magnets to accelerate the payload, over and over, until you've reached sufficient speed to let it fly.
Unless the circle was ridiculously large (probably the size of a continent or better), you're not going to be able to get up to escape velocity before you'd (as a human being) would be crushed by the effects of the centripetal acceleration.
I'm not going to do the math right now, but I'm pretty confident that of the 6,000 Gs they're quoting, most of them are in the radial direction and not in the tangential, so that even if you brought the payload up to speed slowly, you'd still be crushed. It would be just like being in a centrifuge.
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The reason that most meteors don't hit the ground is because they are so small. The one that do hit the ground and are found right away often have FROST on them since they were so cold in space. As for exploding into a million pieces, meteors aren't designed for reentry.
Any compentent aeroshell engineer could design a case that would protect the payload (such as a capsule covered with the stuff they use for ablatively cooling rocket nozzles). The big concern usually with burning through airframes isn't that we don't have materials that can withstand the heat and friction; it is that those materials typically aren't very light-weight or are too expensive.
Besides, once the track is set up, it should be easy to try out new aeroshell designs! One of the stumbling blocks right now is trying to accellerate a test article to high enough speeds. Very often, they stick a test article on a sounding rocket that sends back data during re-entry.
And yes, IAARS.
science is a religion
I think a lot of folks here are confused about the "2000 gs" part of this device. This acceleration is from the centripetal acceleration needed to keep the payload moving in a circular path.
Here's the math:
The acceleration A needed to keep something moving at speed V in a circle of radius R is V^2/R.
A = (8 000 m/s)^2 / (1000 m) = (64 000 m/s/s) = 6 400 gs.
TFA says "More than 2000 gs" - my guess is that this is a mixture of sloppy journalism, and maybe confusion over the minimum acceleration needed to get to escape velocity (about 5.5 km/s). If they did get their wires crossed and report the 8 km/s figure but the g force of getting to escape velocity, the needed A is:
A = (5 500 m/s)^2 / (1000 m) = about (30 000 m/s/s) = 3 000 gs, so they're still wrong.
Incidentally, I love the ring idea, but it could only ever launch pretty specialized cargo due to the g forces needed. What I'd love to see would be a linear accelerator which got a rocket up to about 3-4 km/s, then the rocket would take over. EM launching systems with reasonable length can be built for low speeds, and rockets have high efficiency only when they're already moving fast (otherwise, most kinetic energy goes into making the exhaust, and not the payload, go fast), so a switchover plan seems pretty natural (except that it demands all the infrastructure of a small EM launcher as well as all the problems of a chemical fuel rocket - although some of these problems are less of an issue if you can accelerate the rocket to faster than the fuel's exhaust velocity before it reaches the muzzle of the EM launcher - then your shiny equipmetn doesn't get burned.)
My 2. Enjoy!
Expected time to finish is 1 hour and 60 minutes.
TFA mentions they're going to accelerate it in a circle, to about 10 km/s, and then divert the launch projectile onto a ramp which will deflect it upward at a 30 degree angle, at about 8 km/s. There's a huge amount of energy dumped into the ramp there... why not build the accelerator at a 30 degree inclination to the horizontal, and then all you have to do is let it go at the appropriate time, and you won't be losing 20% of your speed due to the friction of the ramp.
Less is more.
This is merely an engineering question. Engineering something to stand 2000 g's is not difficult, it's just a matter of safety factors. We have developed shells and complex electronics which survive 20,000g's.
The energy use would also be far lower, since you don't have to lift the fuel into space along with the payload.
I have a girlfriend whose name doesn't end in
Am I crazy, or did they get the math wrong in the article?
The acceleration equation for circular motion is: a = v^2 / r
We are given:
Velocity: 10 kilometers/s
Width of ring = 2 kilometers, so radius = 1 kilometer
So:
v = 10,000 m/s
r = 1,000 m
a = (10,000 m/s * 10,000 m/s) / (1,000 meters) = 100,000 m/s^2
The acceleration due to gravity is about 10 m/s^2
This gives: (100,000 m/s^2) / (10 m/s^2) = 10,000 g
So it seems that their 2,000 g is way off. Even if we use 2 km for the radius it is still 5,000 g.
Reading code is like reading the dictionary - you have to read half of it before you can go back and understand it.
Real rail guns have names like "Big Bertha", "Julie" or "the Paris Gun".
Physics geeks need to make up a new name for their amped-up jacob's ladders and stop stealing googlespace and wikishare from World War veterans.
Why can't it be a spark gun? A jake gun? A Tesla gun? Oh, that last one's taken.
The long-term expensive part about space is not sending equipment up. It is the costs of fuel, water, air, and food i.e. consumables. Fuel and Water can all withstand the high Gs. If this works, the first thing that would make sense is to send all of these up. At that point, you can make the ring pay for a large part of its costs. From there, sats. can be developed that can withstand those forces.
The down fall is that the privatization world will probably be a bit upset about this.
I prefer the "u" in honour as it seems to be missing these days.
Geez... There are all sorts of things that you might want to fling into space where you don't really care that much about being gentle. For example, use it to fling food and water up to the space station.
Federal Express, when it absolutely, positively has to be there at 23 times the speed of sound *
* Disclaimer: 23 X speed of sound service available between limited destinations. May be subject to 2000g so please wrap delicate items approprately.
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This ring could fling mass up to a skyhook to recharge its orbit. Imagine a LEO skyhook that catches dozens of dead weight shots from this gun and uses that momentum to promote its orbit to a highly eccentric one. Then the satellite can exchange this orbit potential with a target at its low altitude point through a tether or skyhook style method. The target could be a large satellite in LEO or even a suborbital payload. Once the potential is transfered the target can have its orbit promoted to GEO or other significant altitude.
This method saves a lot of reaction mass in a heavy lifter because you can aim for a high alitutde but a suborbital trajectory. IE it's easier to shoot straight up than curve towards an orbital path at sufficient speed. For instance the X prize is all about sub-orbital. LEO is much harder and GEO is even harder still.
A 2-km-wide ring of superconducting magnets would contain and propel a payload, accelerating it over a period of hours,
So it's wasting all that energy making it go around in circles (it's changing direction, thus accelerating) while it ever-so-slowly ("a period of hours"!? ye gods and little fishes!) to escape velocity. I got news for you -- a low acceeration rocket like the Shuttle makes orbital velocity in 8 minutes at a modest 3 Gs.
Orbital velocity is about 7km/sec. Say 10km/sec to allow for drag losses escaping the atmosphere and gaining altitude. Accelerate at 1000 G and you can reach that speed in 1 second, in a distance of 5 km.
They're talking about a ring 2 km wide; take that as the diameter and they're talking a 6.28 km circumference. With fewer magnets and less total energy they could do it with a linear accelerator.
What idiot wasted taxpayer dollars thinking this up?
-- Alastair
What I wonder about is whether a maglev would be able to support the weight of the payload. If the centrifugal force is 2000 Gs, then the equivalent weight of a 500 Kg satellite being launched would be 1000000 Kgs. I would think they would need awful big magnets to provide enough repulsion to prevent the load from hitting the structure supporting the magnets. And if the magnets were powerful enough, they would need the material holding them in place to be strong enough to not allow the magnets to be ripped or pulled out of place. Imagine if a payload with an apparent weight of 1 Megatonne came into contact with the cement supporting the magnetic track while moving at 8 Km per second. It might be like a small atomic bomb. Now what if they were trying to launch a section for the space station at say, 10,000 Kgs earth normal weight, but now it weighs 20 Megatonnes? I think structural engineering and building a magnetic system powerful enough to prevent things like this will be very hard to overcome. I know that the closer together the magnets get, the more powerful the repulsion, but I still would doubt if we had magnets that powerful. One touch at those speeds with that weight... Also, what would the effect be on a people or materials from magnetic fields powerful enough to overcome those forces?
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The down fall is that the privatization world will probably be a bit upset about this.
The current crop of privateers, yes. If a space-oriented VC could envisage a suitable marketing plan, this would be the ideal private space infrastructure project. Most of the existing cheaper-faster-better startups focus merely on making a cheaper tube 'o fuel. Our current crop of missile makers are still basically building their product by hand. When a launch vehicle and payload go BOOM, a good portion of the contractor's and customer's capital goes with it. It's like watching the auto industry before Ford.
If a Paul Allen or consortium were to bankroll something like this, they wouldn't be betting the farm on each test launch.
Luke, help me take this mask off
Space burials (presumably of cremated remains).
Somewhere in space, there is a planet full of bugs, with giant balls of cremated humans hitting it, and a bunch of bug news programs showing grainy footage of our magnetic ring used to launch our rain of terror upon their world.
transporter_ii
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This was a point brought up at the presentation. One of the linear accelerator guys was pretty sure that the struts holding the tracks in place would be transmitting huge amounts of energy, thereby heating the super-conducting magnets and possibly causing the struts to fail. The Launchpoint guy was sure that they had looked at the problem thoroughly though and that there wouldn't be an issue. Time will tell on that one...