Giant leap for space elevator tech!
- Thread starter epicstruggle
- Start date
Right I know, but what about building it up Mt. Everest or something (though I guess earth quakes would ruin that).
The heat shield would make it weigh more which means more energy to get it to reach the speed necessary. I don't know, but it still seems like the technical challenges might be less than a space elevator. Or wasn't there some laser thing where they could shoot a laser at the bottom of a craft and make it rise?
Well, think about it this way: if we want to descent from orbit, we need some kind of heat shield to protect us. As our craft gets lower and lower in the atmosphere, it slows down and the heat isn't so bad.
A gun firing from the ground wouldn't be a symmetric situation. You'd need to make sure that after slowing down through the atmosphere, the satellite in question would still have enough velocity to maintain orbit. So it'd have to be traveling much faster than orbital velocity by the time it leaves the gun. I'm not even sure we could build a heat shield that would survive, even if we went as high as 10,000 meters or so. It seems to me we'd have to go much higher before the atmosphere was thin enough.
WhiningKhan
Regular
But the counterweight of the cable above the geosynchronous orbit would be rotating at a higher speed than escape velocity. Don't we get essentially free deep-space launches that way?
No we get free launches to geosynchronous orbit. Anything in orbit hasn't escaped the Earth's gravity (by definition).
If it's constructed to counterweight solely by having a very long cable, you really wouldn't want to launch anything off the end. That cable would whip back extremely hard due to the coriolis force.
The bolded portion made me think of the UAE for some reason.
What UAE? United Arab Emirates, Unix Amiga Emulator, User Agent Entity?
WhiningKhan
Regular
How hard? Wouldn't the effect be proportional to momentum of the object that is detached? If the launched mass is small compared to the counterweight system, couldn't the oscillation be allowed?
That's going to depend upon a lot of things, such as the velocity of the object along the line and whatnot. And without an atmosphere to damp the oscillations, I can't imagine that you'd want any significant oscillations going on.
But I've heard of no serious space elevator proposals that would have just a straight line. They typically have us migrating an asteroid into Earth orbit and using that as an anchor. Then it's not quite so bad as you just don't launch anything at a high velocity or that's comparable in mass to the counterweight. But it still has the problem of oscillations generated every launch that you would have to deal with.
WhiningKhan
Regular
Wikipedia's current article seems to suggest the same ideas:
http://en.wikipedia.org/wiki/Space_elevator#Counterweight
http://en.wikipedia.org/wiki/Space_elevator#Launching_into_outer_space
While this would cause oscillations, couldn't we use low-acceleration propulsion at the counterweight to damp the vibrations gradually? Or take the vibration into account in the next launch, so that successive launches cancel the vibrations caused by earlier launches?
I don't think that placing propulsion on the counterweight would be productive. Seems to me that it would just defeat much of the purpose of the space elevator in the first place. As for timing the next launch, I'm not sure that will work either, as these aren't going to be simple vibrations. It may be a long time before the vibrations come back to the opposite of the original configuration.
The only way to counter vibrations is to actively push against the vibrations with rocket engines every so many kilometers. In any case, the stress levels would be raised greatly by any vibration or by trying to cancel one, which would require materials with multiple times the needed strength. Which would be a problem all by itself, as the highest-strength materials we can think of (nano-tubes) might just work without vibrations.
Continuing this line of thought, you wouldn't be able to anchor the cable at all, as it would tear anyway eventually, no matter what material you use. Which would require a free-floating cable. And I have no idea how you could possibly get it to stay put. Which you would want to be able to use the elevators. Or perhaps a huge airship/carrier with some nuclear power plants could be used instead.
Anyway, the easiest solution that could be build today would be a linear accelerator on the side of a mountain. It would still require a second (and third, for high altitude) rocket stage, but you could lose the first stage, which makes up most of the rockets used today.
Continuing this line of thought, you wouldn't be able to anchor the cable at all, as it would tear anyway eventually, no matter what material you use. Which would require a free-floating cable. And I have no idea how you could possibly get it to stay put. Which you would want to be able to use the elevators. Or perhaps a huge airship/carrier with some nuclear power plants could be used instead.
Anyway, the easiest solution that could be build today would be a linear accelerator on the side of a mountain. It would still require a second (and third, for high altitude) rocket stage, but you could lose the first stage, which makes up most of the rockets used today.
United Arab Emirates. As good as the Unix Amiga Emulator sounds when talking about paying off the space elevator I don't think it's in the running.
Ive read at least 3 sci-fi books where these elevators come crashing down
but hey Im all for the idea.
If ppl are willing to pay virgin $100,000 for 6 minutes of weightlessness at 100km high (I think this venture will fail btw),
they could perhaps even turn a profit on this spaceelevator.
How many ppl would pay $10,000 to go up ~300km (imagine the view) + float around, I'm sure they'ld have waiting lists years long.
An idea I had, build a huge mountain in the northern territory or WA, 15-25km high (Im not sure the max height u could build things on earth)
Another huge tourist attraction btw
have enclosed ramp/s on the outside,
either
A/ shoot payloads into orbit, using the whole tube as a barrel (perhaps create vacuum first, cover the end with a film of course).
B/ rockets with humans, launched from near the top
if humans could build the pyramids 4500 years ago something like this should be a walk in the park
but hey Im all for the idea.
If ppl are willing to pay virgin $100,000 for 6 minutes of weightlessness at 100km high (I think this venture will fail btw),
they could perhaps even turn a profit on this spaceelevator.
How many ppl would pay $10,000 to go up ~300km (imagine the view) + float around, I'm sure they'ld have waiting lists years long.
An idea I had, build a huge mountain in the northern territory or WA, 15-25km high (Im not sure the max height u could build things on earth)
Another huge tourist attraction btw
have enclosed ramp/s on the outside,
either
A/ shoot payloads into orbit, using the whole tube as a barrel (perhaps create vacuum first, cover the end with a film of course).
B/ rockets with humans, launched from near the top
if humans could build the pyramids 4500 years ago something like this should be a walk in the park
A linear accelerator is the same thing I was proposing no?
It might be better to build it in australia than up some mountain. They don't seem to have much in the way of earthquakes there.
In the sense that many people call Gauss guns railguns, yes.
Yes, but the density of the atmosphere diminishes relatively quickly with height, and it's what absorbs most of the initial energy. So the higher you can get at launch, the better. And as the rotation of the Earth helps as well and at higher orbits equatorial ones are preferred, the closer to the equator the better.
yes thats part of the reason why I suggested NT or WA for constructing a 15+km high mountain
A/ australia is the most dormant place on the planet
B/ its pretty close to the equator (much closer than florida)
C/ theres lots of readily available rock
D/ as outback oz is prolly the most boring place on the planet (this is mainly due to #A) a mountain will be a welcome improvement to the scenery
I wonder how much something like this would cost to build?
A/ australia is the most dormant place on the planet
B/ its pretty close to the equator (much closer than florida)
C/ theres lots of readily available rock
D/ as outback oz is prolly the most boring place on the planet (this is mainly due to #A) a mountain will be a welcome improvement to the scenery
I wonder how much something like this would cost to build?
Unknown Soldier
Veteran
Actually I believe they showed a Space elevator first in Armitage III - Polymatrix/Dual Matrix.
US
I still have serious doubts about the possibility of actually successfully launching something into orbit, though. It just seems to me that the air friction would make it nigh impossible to build a vehicle that could survive. And the accelerations might be too great for human flight.
