Huge 'Launch Ring' To Fling Satellites Into Orbit

New Scientist ^ | 10-3-2006 | David Shiga

[blam]

Huge 'launch ring' to fling satellites into orbit

16:00 03 October 2006
NewScientist.com news service
David Shiga

A ring of superconducting magnets fires a projectile off a ramp at 8 kilometres per second, fast enough to reach orbit (Artist’s conception: J Fiske/LaunchPoint)

A cone-shaped shell would protect the payload during its passage through the atmosphere into space, and includes a rocket at the back end to adjust its trajectory (Illustration: J Fiske/LaunchPoint Technologies) An enormous ring of superconducting magnets similar to a particle accelerator could fling satellites into space, or perhaps weapons around the world, suggest the findings of a new study funded by the US air force.

Proponents of the idea say it would be much cheaper than conventional rocket launches. But critics warn that the technology would be difficult to develop and that the intense g forces experienced during launch might damage the very satellites being lofted into space.

Previous studies have investigated the use of magnets to accelerate satellites to the high speeds required for launch. But most have focused on straight tracks, which have to gather speed in one quick burst. Supplying the huge spike of energy needed for this method has proven difficult.

The advantage of a circular track is that the satellite can be gradually accelerated over a period of several hours. And the setup is technologically feasible and cost effective, suggests a recent, preliminary study of the idea funded by the air force's Office of Scientific Research.

The air force has now given the go-ahead for more in-depth research of the idea. The two-year study will begin within a few weeks and be led by James Fiske of LaunchPoint Technologies in Goleta, California, US.

The launch ring would be very similar to the particle accelerators used for physics experiments, with superconducting.

[SauronOfMordor]

To get down to the 8g range, that would need a ring with a of diameter of 9,936 miles (16,000 km). Don't think that would fit inside the US.

The centripetal acceleration formula is a = v^2/R. One G is 9.8 m/s^2

For a ring 500 km in radius, and v= 8km/s, we get 8000^2/500,000 = 128 m/s^2 = 13G's

[Centurion2000]

Imagine a power plant (nuclear would be ideal -- it's a good base-load provider) built in the center of the ring. During peak hours, the plant sends juice over the wires as usual. Off peak, the plant feeds excess power into the ring's accelerator magnets. Instead of lofting a spacecraft into orbit, the ring magnets use the juice to accelerate a conductive body (say an iron slug) to the maximum speed mentioned in the article,

Why not just use it with compressed air? Maybe a little less eficient using compressors and wind turbines, but you're not risking a nuclear explosion.

[marron]

Curvature radius of at least 1000 miles, so you might as well make it straight.

You're probably right. Something I read years ago proposed doing it with a 350 mile track. I think the g forces quoted were pretty serious. I think your reference to dinosaur cartilage is pretty good.

[Owen]

There Ain't No Such Thing As A Free Launch.

This ain't gonna work.

It's gonna melt before it leaves the pad.

[Gradient Vector]

"Dude, that really doesn't seem right. 1.96 RPS across a 10km circle is not going to give you 1300G's. Are you talking about centrifugal or centripedal accelerations?"

a=v^2/r; and the a is in the r direction. So anything in that loop will feel 128000 m/s^2 toward the outside. That would destroy most things.

[OregonRancher]

My head hurts....one second after posting I groaned and almost reached for the gun.....How can I forget lateral g
forces? Must be getting old....

[OregonRancher]

Well, why not make it in the shape of a figure eight; one circle would cancel the others centripetal force...right................. :-)

[ASOC]

re: Niven - Gravity polarizers.

This 'study' is less about science as it is about *pork*. Golita CA is the heartland of beltway bandit defense contractors - Raytheon, TRACOR Flight Systems and so on. Sitting next to Santa Barbara, it is one expensive place to do business.

[Steely Tom]

Most satellites are designed with a single direction high g-load in mind for launch.

Well, the g-load would only be in one direction. At a time, that is.

Nice to see you RA!

(steely)

[RoadGumby]

What?!?

Risking nuclear explosion? Must've been reading on DU for too many years.

[Erasmus]

...one second after posting I groaned and almost reached for the gun...

With which you would have caused a projectile to be subjected to forces causing 450 000 M/S/S acceleration over a distance of 0.1 M and an interval of 0.666 mS, resulting in an exit velocity of 300 M/S. With gory results. < }B^)

[ryan71]

This is a cool idea, but I would not use it for satellites. Satellites are fragile pieces of equipment.

This is a gun. It would be more practical to design projectiles that could be launched into space and put into orbit until needed. During wartime, a target can be identified and the projectile directed to reenter the atmosphere, glide, and use GPS or a laser designator to impact the target.

You could put countless shells into space to be used when needed. No more waiting on Bombers or clearing foreign airspace.

Size? Big, small, even clusters. Warhead? Conventional HE, maybe no warhead, maybe just a kinetic force like our concrete bombs.

[verum ago]

"I propose we use Ted Kennedy to test it at a 200% power setting."

That could throw the earth off it's axis, possibly even out of it's orbit.

oooohh, good point. How 'bout Nancy Pelosi, then?

[OregonRancher]

Not me, my computer.....

[Centurion2000]

Risking nuclear explosion? Must've been reading on DU for too many years.

Oops, risking the equivalent of a nuclear explosion. Read his post and you would see that if the system suffered a catastrophic failure that the kinetic energy release would be equal to a small nuclear weapon.

[Centurion2000]

a=v^2/r; and the a is in the r direction. So anything in that loop will feel 128000 m/s^2 toward the outside. That would destroy most things.

I see it now .... guess my physics is really rusty. Thanks.

[N. Theknow]

The acceleration (in the ring) will be a killer. a = v^2/r. For an 8 km/s speed with a 10-km-diameter circle, the acceleration will still be ~1300G. Typical satellites are designed for the 6-8G range.

OMG! That's right!

[taxcontrol]

I did the math off the top of my head, so let me do this in more detail this time ... check me on this.

A = v^2 / r
if we solve for r we get
r = v^2 / A

or for G's conversion

r = v^2 / (G's * 9.81)
so plugging things in...

r = 8000 * 8000 / 78.4
r = 64000000/78.4 meters
r = 816327 meters
diameter = 1632653 meters or 1633 km (rounded)
I must have flubbed up on my decimal point here.

STILL, that is a 1,000 mile diameter circle. If you planted the center in eastern Kansas, the western boundary would be up in Colorado and the eastern boundary would be somewhere in Kentucky. Basically trying to fit it in between the Appalachians and the Rockies. North part would be up by the great lakes and the southern would run through Texas.

Now, I'm sure that with some engineering, 13Gs for a satellite would be doable. That 500km radius MIGHT be doable. A 25G satellite would be even better but I don't know if we currently have the technology to build electrical components esp computer chips and solar panels to sustain that level of G's.

Now if you could combine this with a recovery vehicle that would carry the satellite but provide lower atmosphere air breathing thrust to offset drag, and perhaps a small booster rocket for high altitude, then you could get away with say 5 km/s.

So recovery sled, plus booster, plus 25Gs would be a radius of:

r = 5000 * 5000 / (25 * 9.81)
r = 25000000 / 245.25
r = 101,937 m
so a 205 km or 127 mile diameter ring. Now that seems more realistic to me. That could be done inside of Texas.

It would be interesting to compare that to the length of a rail gun required to get the same configuration up to the same speed. A cost comparison would be interesting as well. Esp since the ring would need to be build in such a manner as to withstand potentially dozens, maybe even hundreds of tons of lateral force.

[taxcontrol]

Oh, I forgot one other thing. 8 km/sec is like Mach 15. Some other technologies are going to be needed here I'm sure.

[Aquinasfan]

the intense g forces experienced during launch might damage the very satellites being lofted into space.

Yeeeeah. What's the diameter of this thing? Interesting idea though. Would it require any less energy than a rocket? And what about air friction at launch? The satellite would be red hot.