Huge 'launch ring' to fling satellites into orbit

[epicstruggle]

http://www.newscientistspace.com/ch...unch-ring-to-fling-satellites-into-orbit.html

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 magnets placed around a 2-kilometre-wide ring.

 

[Simon F]

Surely the acceleration required to just hold it in the ring must be fairly enormous too!

 

[Cartoon Corpse]

banked track....halo!

the flinger!

 

[Guden Oden]

A 2-kilometer diameter ring would exhibit rather extreme G-forces, not to mention atmospheric pressure at launch velocity speeds... Sonic boom = super understatement... Energy losses must be enormous, especially if this thing is supposed to run for HOURS. Seems like a fairly dumb idea to me.

 

[Bouncing Zabaglione Bros.]

Okay, so you've got all these electronic components, and even if they are hardened for spece, you're going to fling them around at high speed and gee while keeping it all in a massively strong magnetic field for several hours?

Will they still work? Will stuff like solar panels get magnetised and not be able to open in space? Is everything electronic get the equivalent of an EMP hit?

 

[MPI]

Okay, so you've got all these electronic components, and even if they are hardened for spece, you're going to fling them around at high speed and gee while keeping it all in a massively strong magnetic field for several hours?

Will they still work? Will stuff like solar panels get magnetised and not be able to open in space? Is everything electronic get the equivalent of an EMP hit?

Well, are all cellphones and laptops being zapped into oblivion on those maglev trains?

Besides, it sounds pretty damn tame impulse-wise compared to other ideas put out there, space cannon et.al.

 

[Sc4freak]

They won't really be subject to high gee forces if you take long enough to accelerate the satellites. Escape velocity on the surface of the Earth is only ~11km/s, so if you accelerated it at 0.5m/s^2 (which isn't particularly fast) you'd reach escape velocity of 11km/s in 6 hours.

Its the exposure to extremely strong magnets for 6 hours I'd be worried about. Possibly also the effects of air resistance on a satellite travelling though the lower atmosphere at 11 km/s.

 

[3dilettante]

I think the field won't vary too much within the ring, so the EMP problem won't be so bad. It's more of a gradual push over a long time than a strong zap.
The interference can be buffered somewhat with hardened equipment and shielding, or they could make the capsule superconducting and block most if not all of the pulse.

My biggest concern is the problem with going to escape velocity in the lower troposphere. That's going to be brutal.

edit: Maybe more than escape velocity is needed, counting air resistance.
The cost of accelleration at atmospheric pressure alone would reduce or eliminate the energy savings right there.

They could evacuate the tube, but then there's the problem with the mechanical and (edit- thermal) shock of flinging something that fast right into a wall of air on launch.

 

[Sc4freak]

Hmm, if they keep the tube pressurised, I wonder if sonic booms caused by the satellite will affect the structure of the tube? Massive changes in air pressure inside the tube can't be good, can it?

 

[Bouncing Zabaglione Bros.]

Hmm, if they keep the tube pressurised, I wonder if sonic booms caused by the satellite will affect the structure of the tube? Massive changes in air pressure inside the tube can't be good, can it?

It would be hugely more efficient if you evacuate the air from the tube, but as has already been pointed out, that means when it's ready to go, you'll fling the satellite straight out at high speed into a wall of much denser air.

There has been some work been done on dramatically decreasing air resistance using ionised streams over the wings of aircraft, so maybe you'd need something similar to make the projectile slippery through the atmosphere.

 

[Simon F]

They won't really be subject to high gee forces if you take long enough to accelerate the satellites. Escape velocity on the surface of the Earth is only ~11km/s, so if you accelerated it at 0.5m/s^2 (which isn't particularly fast) you'd reach escape velocity of 11km/s in 6 hours.

Cough! You do know that changing direction involves acceleration and when going in a circle you are constantly changing direction....

If I remember my physics correctly, the acceleration acting on the object just to keep it in that ring would be v^2/r which equates to only 11000^2/1000 => 121000m/s^2 => 12000G.

Someone tell me if I've got that wrong!

 

[Sxotty]

My biggest concern is the problem with going to escape velocity in the lower troposphere. That's going to be brutal.

edit: Maybe more than escape velocity is needed, counting air resistance.
The cost of accelleration at atmospheric pressure alone would reduce or eliminate the energy savings right there.

They could evacuate the tube, but then there's the problem with the mechanical and shock of flinging something that fast right into a wall of air on launch.

That is exactly the problem with all this stuff. Air resistance kills it.

But the solution is simple launch it from a higher starting point. So around and around to speed up then bank it up and go straight up a tube that is high, Then you have the engineering problem of how high you can make the tube etc... but I think at some point in the future it will be done.

Anything launched in this way would have to be able to survive enormous accelerations – more than 2000 times the acceleration due to gravity (2000g). This would seem to be an obstacle for launching things like communications satellites, but Fiske points out that the US military uses electronics in laser-guided artillery, which survive being fired out of guns at up to 20,000g.

Edit:
BTW think about making stuff in space like a moon base. Sure 10kg isn't much, but if you could just fling one part after another out. Some things might be sensitive, but other stuff wouldn't car about the g force really...

 

[London Geezer]

Okay, so you've got all these electronic components, and even if they are hardened for spece, you're going to fling them around at high speed and gee while keeping it all in a massively strong magnetic field for several hours?

Will they still work? Will stuff like solar panels get magnetised and not be able to open in space? Is everything electronic get the equivalent of an EMP hit?

In their defense, they didn't say anything about launching working satellites. They're just launching them, if they don't work by the time they get up there, it's not their problem!

 

[AlNom]

In their defense, they didn't say anything about launching working satellites. They're just launching them, if they don't work by the time they get up there, it's not their problem!

giant surface-to-surface cannon balls

"yah... it's a satellite... by definition.....for 10 seconds."

 

[DudeMiester]

Well, you certainly wouldn't build it at sea level, so why not build it on top of a mountain? Obviously you can't at the very top, but you could build a ring around one farther down. Hopefully that will be enough to thin the air sufficently. Even then you could just make the exit tube really long.

 

[DemoCoder]

A friend of mine worked on this: http://www.astronautix.com/lvs/sharp.htm

The goal of such systems wasn't envisioned to put satellites into orbit, since the payloads are severely limited in size. Rather, these systems could launch tons of materials into orbit for construction and interplanetary missions: fuel packets, water, freeze dried food, shielding, inflatables, etc. Then you could launch your moon or mars vessel without having to carry all the payload for the journey into orbit. This means the launcher for the ship can either be cheaper, or the ship can be bigger.

 

[Frank]

Solid state electronics can withstand an extreme amount of punishment. Unfortunately, moving, mechanically connected and/or containers holding liquids cannot. And real satellites consist of all of that.