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Inflatable tower could climb to the edge of space
- stcredzero 17y agoA series of towers that could suspend a magnetic accelerator about 300 miles long above the bulk of the atmosphere would be almost equivalent to a Space Elevator. (A space elevator transfers angular momentum from the Earth's rotation into the orbital velocity of the cargo. Most of the work needed to attain orbit is involved in the lateral acceleration, not in gaining altitude.) It would be about as heavy as one, though.
- rbanffy 17y ago"A series of towers that could suspend a magnetic accelerator about 300 miles long above the bulk of the atmosphere would be almost equivalent to a Space Elevator." The problem is that during acceleration you would push the tower back with a force greater than the weight of the craft being accelerated. I am not sure how much load those inflatables would bear, but I would guess that it's in the "not much" range.
- randallsquared 17y agoTether it to a large mountain.
- stcredzero 17y agoThis is why you'd want a series of towers, so that the force would be distributed. Also, you'd have the accelerator start at the ground, so the structure could be tethered there.
- mnemonicsloth 17y agoThis is a bigger deal than it looks. The space elevator cable has to support its own weight, so the stresses on it increase exponentially with length. Not having to support those last 20 miles of cable could take the space elevator concept a big step closer to reality.
- rbanffy 17y agoA tower extending 100 Km up would be a great point for scientific observation. But to be a space elevator replacement you would need a tower that could bear load up to geosynchronous orbit. That's not easy. I have read about using a series of balloons for lifting - a more rugged one for low atmosphere, then switching the cargo to a lighter one designed to operate in the high atmosphere and then propelling the cargo with something like an ion engine to orbital speeds and increasing heights where the balloon would give less and less lift (and offer less and less drag). Looks like an interesting idea.
- mnemonicsloth 17y agoBut to be a space elevator replacement you would need a tower that could bear load up to geosynchronous orbit. That's not what I'm suggesting. Build the tower as high as is practical, say 100 km. Then launch your space elevator satellite and lower the cable down to the top of the tower. The cable has to support its own weight, so it has to be thicker at the top than at the bottom. It turns out that the cable thickness has to taper exponentially (basically, this amounts to a rotation of the catenary problem). So not having to support the last 100 km of cable at the end translates into a weight savings along its entire length.
- rbanffy 17y ago"He calculates the tower could be extended up to low Earth orbit at 200 kilometres." 200 Km standing on top of an inflatable toy is not low Earth orbit! Who writes this stuff?
- stcredzero 17y agoGetting to the height of low earth orbit could still be useful. Once you're that high, it's much easier to accelerate something to orbital velocity.
- Semiapies 17y agoIs there even enough commercially-available helium in the whole world to support this structure, much less a 100+ km tall version?
- randallsquared 17y agoWhen you're talking about floating structures measured in miles, it doesn't matter. You could do it with small temperature differences. You could float a half mile geodesic sphere with only a degree or two of temperature difference and ordinary air.
- Semiapies 17y agoHmm, good point.