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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."
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
Indeed. also Man who Sold the Moon. Also, if you rememeber 1962: Fireball XL5 http://www.aiai.ed.ac.uk/~bat/GA/fireball-xl5.html -There is a model of the mag lift launcher on that page. The concept has been there for years. Sure it would not work for transporting passengers, but supplies? Chucking O2 cans, rocket fuel, even space food and station building parts into low orbit would become very cost effective.
- Minutus cantorum, minutus balorum, minutus carborata descendum pantorum.
"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.
Actually, I think it could work for passengers. It would be the accelleration forces that would do harm, not the speed itself. So basically, all one would need is a longer runway with a more gradual accelleration to reach escape velocity.
"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.
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.
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.
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
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
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.
I'm not sure there's enough room. If you're trying to get to LEO you need to get to 8km/s. If you want to subject people to no more than 1 additional g (remember, they're still on the ground, so you get 1 g for free), that's a radius of 6,400 km, if I do the math right, and that's just about the radius of the entire earth.
Having done all that math, it's not a coincidence. LEO is essentially the same as the surface of the earth, so velocity to LEO is just about the same as at the surface, which is always going to be (g*r)^1/2.
Once your ring was that big you woudln't actually be subjected to the gravity down as well. You'd actually be in free fall. But if you scaled down the ring, your vectors would no longer be opposite, and you'd start to feel the combinations of the weight again.
You could reduce the ring and scale up the gravity, but you're still talking about considerable fractions of the radius of the earth, all built with the kind of precision to handle an object moving faster than a speeding bullet.
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.
(Had a few beers as is right and proper for me, not sure if I'm joking or not. Mod gently, kind sirs).
It's true I tell you, feller at work's next door neighbour read it in the paper.
I was at a presentation last week by the guys in this article.
The track design is based on particle colliders, so the entire thing is evacuated. Part of it is a rough vacuum and part is a hard vaccum (the actual track). The rough vacuum is because they have to limit thermal transfer to their super-cooled superconducting magnets.
The acceleration is actually not linear- it's radial. Going around a 2km track at 10km/s has some hefty acceleration associated with it. When ejected into the atmosphere, the projectile shouldn't immediately slow a great deal, although it will lose a lot of momentum before leaving the atmosphere. The design is a very long and skinny cone, to reduce thermal heating and drag force.
The best thing about this design for a launcher is that it doesn't require a lot of instantaneous power, unlike a linear accelerator. You can accelerate slowly.
Also, did anyone else immediately think of Xenogears when they saw this?
Not all that funny. Make a payload of tungsten and some type of guidance system and you have a fractional orbital bombardment system. A 1000lb slug of tungsten hitting a target at 18,000 mph would make a nice sized hole.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
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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Probably not, as this had already been investigated to help design earlier space suits:
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.
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The gaseous explosion doesn't happen, fortunately. During the Appolo program, a guy in a vaccuum chamber fell down and shattered his face mask - he was very suddenly exposed to total vaccuum. He was consious for a few seconds (say 5-10), and then passed out. It took them another few seconds to bring the chamber back up to atmospheric (say about 20-30 seconds). He was resuscitated, and had no long term injuries from the experience.
while (sig==sig) sig=!sig;
Oh, so how much mass gets dumped out the back side of ANYTHING that moves in space? Satelites are limited by the amount of propellant mass they can bring with them. Space stations need to boost them selves to maintain orbit. Oh, and they wanted to kick something over to mars right? That means proprotionally equal junk shooting out the shuttles ass. How much mass does the shuttle bring up just to putter around in space with?
... aerodynamics isn't my field. Still, that energy is dangerous...dump it back down with some basic guidance and you can hit anywhere on the planet with minimal notice. Or how about as an anti-satelite weapon? You don't need much mass or anything more than a basic fragmentation grenade to take out just about anything we currently throw up in orbit. If you can aim your toy then you can throw things on ballistic trajectories too...your "super gun" tossing refrigerators at iraq from the midwest USA.
So how about if I told you the next mission to the moon/mars/uranus didn't have to lug fuel into space with the ship or run shuttle trips full of 'dead mass' to supply it? Hrm, that sounds pretty darn useful all of a sudden, eh? I'm pretty sure a solid block of fuel (or inert mass for ion drives, nuclear rockets, etc.) with some aerodynamic abaltive coating could survive a couple thousand G's of accelleration.
You can launch hundereds of slugs into nearly identicals orbit tagged with basic transponders, pick em up, strip off the ablative coating and you've got your multi-tonne reaction mass for pennies on the dollar. Yes, it'd be a pain in the ass to collect hundereds of slugs in similar but different orbits but still far far cheaper than paying to lug it up via our wonderful but antiquated shuttles. Heck, you could even park slugs in high orbit for emergencies, spare reaction mass, or whatever you'd like.
Ok, and the weapon use like everyone needs to talk about. Throw a tonne of mass into space and you keep a significan percentage of the energy you spent getting it there. Dun ask me what %
A question i was wondering about. Firstly would this result in eveerything that it launches all ending up orbiting near each other, it would be useful for building a space station i guess but what about beyond that.