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Space Fountains

Aitch

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Came across this on another board - the Space FountainWP.

Had a read of it, but it doesn't feel right. I don't know enough physics to work it out, but it looks to me like it would be fine until you tried to use it to lift something, at which point the energy costs would increase dramatically.

Any recently-qualified physicists like to comment.

I did a simple search for previous threads on the subject but couldn't find amy - did I miss one?
 
Aitch said:
Came across this on another board - the Space FountainWP.

Had a read of it, but it doesn't feel right. I don't know enough physics to work it out, but it looks to me like it would be fine until you tried to use it to lift something, at which point the energy costs would increase dramatically.

Any recently-qualified physicists like to comment.

I did a simple search for previous threads on the subject but couldn't find amy - did I miss one?
Click to expand...

Seems doable but stupid. It would take a lot of energy, as you are essentialy shooting a railgun and then magneticaly coupling the ship to the projectiles.

It seems that it would take much much more energy than simply using magnets to shoot the ship itself. The energy wasted would be enourmous.

Edit: In a vacuum with out frictional losses to the air, it would be less stupid. But you still have a stream of orbital+ velocity massive objects near what you are sending into space. A small alighment problem would blow up your space ship.
 
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Looks to me, off he cuff, like:

What you would have is a bridge anchored by the Earth at one end and by the kinetic energy of the "shots" at the other. It would still have to be supported by those two points; in particular, the lion's share of the weight (say, all the structure above a mile high or so) would be supported under tension by the upper end. I don't see that it would be different from the elevator concept. A distributed design, where the kinetic energy of the shots is robbed along the way to support each segment of the fountain would be better, but also would require more machinery (ie, weight). The only plus is that the fountain doesn't need to be 40,000 miles high as the space elevator requires, but I think it would have to be a miinimum of 120 miles high to get into low earth orbit. Anything launched from the top would have to provide it's own escape velocity minus the speed of the top of the fountain, pretty much what has to be supplied if it launched from the Cape (although it wouldn't have to fight air resistance). In fact, it would have to add the difference of it's rotational momentum at the top from that on the ground in order not to degrade the fountain head (no pun intended).
 
Looks to me, off he cuff, like:

What you would have is a bridge anchored by the Earth at one end and by the kinetic energy of the "shots" at the other. It would still have to be supported by those two points; in particular, the lion's share of the weight (say, all the structure above a mile high or so) would be supported under tension by the upper end. A distributed design, where the kinetic energy of the shots is robbed along the way to support each segment of the fountain would be better, but also would require more machinery (ie, weight). The only plus is that the fountain doesn't need to be 40,000 miles high as the space elevator requires, but I think it would have to be a minimum of 120 miles high to get into low earth orbit. Anything launched from the top would have to provide it's own escape velocity minus the speed of the top of the fountain, pretty much what has to be supplied if it launched from the Cape (although it wouldn't have to fight air resistance). In fact, it would have to add the difference of it's rotational momentum at the top from that on the ground in order not to degrade the fountain head (no pun intended).
 
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Someone else reads xkcd eh?

I read the wiki but wasn't clear on what these "projectiles" would be. are we talking particles? Golf balls? Wrecking balls? Katamari Damacy balls?
 
:eye-poppi

This thing must be built. I don't care how dangerous, expensive, or labor intensive it is. I don't even care if it has no practical purpose. Need slaves? Here...

*Loads grandmother onto slave shuttle*

Don't worry about energy. Anything this awesome would be powered by its own sense of self-satisfaction.
 
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