Space Fountains - GEO Elevator, no nanotubes required

Mad Grad Student · 2004-08-02 16:07:24

http://en.wikipedia.org/wiki/Space_fountain]Space Fountains

This is an interesting concept (Why didn't I think of this before?). The space fountain works pretty much like a typical space elevator, except that instead of hanging limply from geosynchronous orbit it is supported by a rail gun. Tiny projectiles are propelled up into the tower and are gradually slowed down by electromagnets to zero velocity at the top. There they loop around and fall back to Earth, loop around once more at the base (As in a particle accelerator), and are shot back up the tower. The advantage this has over traditional space elevators is that with the rail gun's support the tower doesn't have to be anywhere near as strong as it would without the assistance, meaning it can be made out of current materials, no carbon nanotubes needed.

The tittle got me thinking, though, would it be possible to make a real space fountain? Get some sort of gun that can shoot little droplets of water up to orbital velocity (HARP-style gun, perhaps?), and fire them off from a huge source of water, like the ocean. The droplets would hit the back of a spacecraft, a la Orion, and slowly propel it into GEO. In this setup, you don't even need to make any sort of tower, and unlike that NASA system under development, you don't need any super-powered lasers to do the job. Just good ol' water.

Obviously both of these ideas are WAY out there, but so are space elevators, perhaps they deserve some attention.

bdunbar · 2004-08-04 09:31:12

http://en.wikipedia.org/wiki/Space_fountain]Space Fountains
This is an interesting concept (Why didn't I think of this before?). The space fountain works pretty much like a typical space elevator, except that instead of hanging limply from geosynchronous orbit it is supported by a rail gun. Tiny projectiles are propelled up into the tower and are gradually slowed down by electromagnets to zero velocity at the top. There they loop around and fall back to Earth, loop around once more at the base (As in a particle accelerator), and are shot back up the tower. The advantage this has over traditional space elevators is that with the rail gun's support the tower doesn't have to be anywhere near as strong as it would without the assistance, meaning it can be made out of current materials, no carbon nanotubes needed.
The tittle got me thinking, though, would it be possible to make a real space fountain? Get some sort of gun that can shoot little droplets of water up to orbital velocity (HARP-style gun, perhaps?), and fire them off from a huge source of water, like the ocean. The droplets would hit the back of a spacecraft, a la Orion, and slowly propel it into GEO. In this setup, you don't even need to make any sort of tower, and unlike that NASA system under development, you don't need any super-powered lasers to do the job. Just good ol' water.
Obviously both of these ideas are WAY out there, but so are space elevators, perhaps they deserve some attention.

This is an interesting concept (Why didn't I think of this before?). The space fountain works pretty much like a typical space elevator, except that instead of hanging limply from geosynchronous orbit it is supported by a rail gun. T

What's the failure mode for a space fountain? If the power source (the railgun) goes ofline for days, weeks or months, what happens?

That's the deal killer for a number of otherwise really keen ideas. When they fail, things go *boom* and not in a good way.

The tittle got me thinking, though, would it be possible to make a real space fountain? Get some sort of gun that can shoot little droplets of water up to orbital velocity (HARP-style gun, perhaps?), and fire them off from a huge source of water, like the ocean

How do you keep the water from vaporizing after it leaves the gun?

Mad Grad Student · 2004-08-04 21:30:49

According to the article, even if all power was lost to the fountain it wouldn't be in serious trouble for at least a few days because of the time it would take for the energy to bleed off. Even then, you could mount two or four (Four is better for symetry) rail guns instead of just one so that if one fails the other can keep the tower aloft. At least that would buy you some time to fix the power.

If that doesn't work, well, you're screwed. I suggest praying to your diety of choice. "Zeus, Bhudda, God, one of you do something! Satan, you owe me!"... :laugh:

As for the water fountain prehaps you could put a little screen of plastic on the nozzle right were the dropplets leave the gun. Once one clears the muzzle, it will get wrapped in plastic, keeping it liquid and still delivering the kenetic force on the payload without damaging it too much.

Of course, you'd end up going trough a lot of Reynold's Wrap baggies by the time you're in orbit. ???

bdunbar · 2004-08-05 12:01:47

As for the water fountain prehaps you could put a little screen of plastic on the nozzle right were the dropplets leave the gun. Once one clears the muzzle, it will get wrapped in plastic, keeping it liquid and still delivering the kenetic force on the payload without damaging it too much.
Of course, you'd end up going trough a lot of Reynold's Wrap baggies by the time you're in orbit. ???

That would be some mighty tough plastic we're talking about.

C M Edwards · 2004-08-05 13:46:58

How good is their aim?

Shooting an apple off of someone's head at 100 paces is child's play compared to this thing.

SBird · 2004-08-06 12:23:44

Eeek, the thought of playing chicken with a stream of projectiles moving at high suborbital velocities is not something I'd like to be anywhere near. The failure mode is when the pellet stream gets a tiny bit off axis and erases a part of the system in a big explosion.

SpaceNut · 2004-08-12 07:54:31

NASA works on far-out propulsion plans
Aerocapture, tethers and atomic power under study,
http://www.msnbc.msn.com/id/5673239/

tether.hlarge.jpg

"The Momentum-Exchange/Electrodynamic-Reboost Tether System, shown in this artist's conception, could pick payloads up from a reusable launch vehicle in low Earth orbit and toss them to geosynchronous orbit."

Granted this system is not from the surface but any reduction in cost from using free energy sources is a plus.

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#1 2004-08-02 16:07:24

Re: Space Fountains - GEO Elevator, no nanotubes required

#2 2004-08-04 09:31:12

Re: Space Fountains - GEO Elevator, no nanotubes required

#3 2004-08-04 21:30:49

Re: Space Fountains - GEO Elevator, no nanotubes required

#4 2004-08-05 12:01:47

Re: Space Fountains - GEO Elevator, no nanotubes required

#5 2004-08-05 13:46:58

Re: Space Fountains - GEO Elevator, no nanotubes required

#6 2004-08-06 12:23:44

Re: Space Fountains - GEO Elevator, no nanotubes required

#7 2004-08-12 07:54:31

Re: Space Fountains - GEO Elevator, no nanotubes required

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