you’d have to have a moving anchor point to take in the orbits of the celestial bodies… just off the bat
One issue that will turn out to be significant, for space elevators, space fountains, skyhooks is that eventually every low Earth orbit intersects their positions. Unless technology - and eerything so far has been hand-wavey - can be developed to let the fixed structures dodge vehicles and junk, having artificial satellites appears to make space elevators impossible.
Lofstrom loops might be an alternative.
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Thank you. I am surprised how far down I had to search to find this reference. The very first paragraph IIRC had the guy who invented the micro filament that made it possible
The problem isn’t one of engineering or materials science or orbital mechanics or energy budget. It’s social.
I mean, yes, we also have to figure out how to make it. But the REAL problem is figuring out how to get ourselves organized into a more or less utterly harmonious and perfect society, which is a prerequisite.
Because as everyone from Kim Stanley Robinson to xkcd has pointed out, space elevators are preposterously susceptible to sabotage. They are, bar none, the softest target human ingenuity has ever conceived of. You can attack the bottom, you can attack the top, you can attack them in the atmosphere, you can attack them at any point along 40,000 miles of tether.
Just sayin’!
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Well, no “medicine” but a single type of treatment could (theoretically) wipe out most forms of cancer and prevent it in the future - gene manipulation. As we find the markers that can cause cancer, and get better with manipulating the human genome, amazing things are possible (nightmarish ones too of course). Most cancers, Haley Haley, and a slew of other genetically rooted maladies SHOULD see their end in teh next twenty years. They likely WON’T, but they should.
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Can we not have Trump in every thread?
Forget the possible dangers, can you imagine the constant noise it would make in the wind?
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Nah, the biggest challenge isn’t the cables. It’s the problem of building it halfway, and suddenly all the workers begin speaking different languages.
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Space elevator? No thanks… chances are at the ground floor some punk kid will be getting out… I would be getting in and THEN notice he’s pushed all the buttons and it will stop at EVERY floor.
I’ve noticed that any TV program that includes these elevators in their story lines, invariably there’s a problem… It’s like you can’t show an explosive device on Mythbusters without blowing it up.
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Charles Sheffield published The Web Between Worlds the same year.
Once we have the space elevator we can use it to cheaply and safely fling cancer off the Earth and into the Sun. Cancer cannot survive the purifying rays of the Sun! … Can cancer survive the purifying rays of the sun? Oh god… sunspots. Cancer Sun has been giving itself melanoma all these years! Once we find the cure for cancer we can use it on ourselves AND the Sun and we won’t need that damned space elevator stinking up the skyline any more.
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Space elevator music?
We’re gonna get hi hi hi…
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Have always loved this track! Great seeing it back in the day in the movie Back to School!
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Yeah this is the thing. The materials don’t exist, and the gap between the strength of current materials and the ones we need is orders of magnitude.
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Question: i’ve not seen the video yet so i don’t know if they cover it but say you want to bring passengers back down to ground level, is there any reason you can’t strap 'em all in and put the whole elevator into free fall? Then half a mile up or so start slowing the thing down so you’re not wiping your passengers off the floor with a sponge. How would you resolve the problem of whatever braking mechanism you use failing? Drogue parachutes and retrorockets? Risky maybe but what a ride…
With regards sabotage, i read a fun little short story recently that tackles exactly that.
I suppose so but I think the usual concept (and this was in the Clarke book) is to generate electric power from descending elevator cars and feed that power to ascending elevator cars. Losses would be filled from the grid. Power may be generated by photovoltaic cells on the tower itself.
The tower may connect to orbiting power stations, and provide transmission lines to Earth.
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And immediately after Girl From Ipanema on Hammond organ.
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I seem to recall Arthur C Clarke (‘any sufficiently advanced fiction eventually becomes indistinguishable from reality’ - didn’t he predict something like that? 
) may have mentioned something similar but it has been a very long time since I read that. (As mentioned above by @exuma - The Fountains of Paradise )
Anyway, you may like this link which discusses it at length in more technical detail. Here’s a brief extract from the intro.
The space elevator (alias Sky Hook, Heavenly Ladder, Orbital Tower, or Cosmic Funicular) is a structure linking a point on the equator to a satellite in the geostationary orbit directly above it. By providing a ‘vertical railroad’ it would permit orders-of-magnitude reduction in the cost of space operations. The net energy requirements would be almost zero, as in principle all the energy of returning payloads could be recaptured; indeed, by continuing the structure beyond the geostationary point (necessary in any event for reasons of stability) payloads could be given escape velocity merely by utilising the ‘sling’ effect of the Earth’s rotation.
ETA: Ah, I see that @Michael_R_Smith has beaten me to it and the great Arthur did not use that concept.
Further ETA - and when you fall in freefall from space do you fall vertically (perpendicular to the point on the Earth that you are directly above) or do you fall in a curve? Maybe if a lift were tied to a strictly vertical cable on the equator, centripetal force would work against freefall? (And if it is not 100% clear already from this drivel, I am definitively NOT a physicist!!)
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What’s your starting velocity? If you’re near enough to the Earth that the gravity of other bodies can be discounted, in freefall, you’re following some conic section. That could be an ellipse with the center of the Earth at a focus (what we call an orbit!), or a hyperbola again with the center of the Earth at a focus (what we call an escape trajectory). Special cases include a straight line toward or away from the center of the Earth, a circle around the center of the Earth, or a parabola with the center of the Earth at its focus. All of these are ‘falling’.
The cable rotates with the Earth. At geosynchronous altitude, your passengers are in orbit. If you just drop them, they continue to orbit alongside it. To get them to fall would require retrorockets to lower perigee to an altitude where you could get the rest of the speed bled off with aerobraking, essentially a spacecraft re-entry. The whole point of the elevator is that you don’t need to do that; in fact, you can recover the energy from slowing your passengers, craft and cargo to the rotational speed at the Earth’s surface.
What happens is that the cable is under constant tension. At geosynchronous altitude, the centripetal acceleration exactly balances the gravitational force. Closer in, the cable experiences some weight, up to a full 1 g at the surface. Farther out, the cable, if cut, would be flung outward. The tension is tremendous. To support its own weight, a space elevator cable would need a tensile strength of about 50 GPa. Structural steels have strengths in the range of about 0.5 GPa.
If you’re talking materials that are commercially available at scale, you’re right, the gap is about two orders of magnitude. But the strength of covalent chemical bonds is in the range so that various single-crystalline materials - cubic boron nitride, diamond, carbon nanotubes, graphene sheets - have tensile strengths in the right range. There’s no technology today for making large perfect sheets of such materials, but folks have been working on it; they’re valuable for lots of other things. (Many of the materials I mentioned are bulk semiconductors with interesting electrical properties if doped with the right heteroatoms.)
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@ 8:03: donated DENOTED
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