Another Space Elevator Proposal
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Funkworks
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I wonder if there might be an asteroid or moon where installing a space elevator might be easier than on Earth.
Somewhat related: I wonder what are the slowest and fastest spinning asteroids and moons in the solar system.
Somewhat related: I wonder what are the slowest and fastest spinning asteroids and moons in the solar system.
from the article:
"For decades, an array of physicists, authors of science fiction, and dreamers have eagerly computed the magnitude of these forces. However, the resulting calculations have consistently led to disappointment. There is currently no identified material capable of withstanding these forces. This includes materials as strong as spider silk, Kevlar, or even the most resilient contemporary carbon fiber polymers.
So this is as impossible as going to Mars.
"For decades, an array of physicists, authors of science fiction, and dreamers have eagerly computed the magnitude of these forces. However, the resulting calculations have consistently led to disappointment. There is currently no identified material capable of withstanding these forces. This includes materials as strong as spider silk, Kevlar, or even the most resilient contemporary carbon fiber polymers.
So this is as impossible as going to Mars.
A space elevator is by far most useful on Earth because, as someone said, once you're in Earth orbit you're halfway to *anywhere*. Well, anywhere in the galaxy. Earth orbital velocity is about 8 km/s. To escape the Sun's gravity at Earth's orbit is about 17 km/s...so in orbit you already have half the velocity to escape the Sun. With the bonus that a lot less propellant is needed to get that extra velocity (in vacuum).
Carbon nanotubes could be used for a space elevator but would require that they be manufactured in *huge* quantities, and in long strips that are aligned with one another. That will probably require some sort of enormous breakthrough in technology. When one considers the anti-science state of the US right now...I don't see anyone other than China being able to attain the breakthrough. Don't know whether I'm being pessimistic or realistic or both...
Carbon nanotubes could be used for a space elevator but would require that they be manufactured in *huge* quantities, and in long strips that are aligned with one another. That will probably require some sort of enormous breakthrough in technology. When one considers the anti-science state of the US right now...I don't see anyone other than China being able to attain the breakthrough. Don't know whether I'm being pessimistic or realistic or both...
Prfesser, even if it were possible to build such a thing, it would be such a long term project that our politicians and corporate leaders wouldn't have the fortitude or vision to let it be built. It'll take longer than an election cycle to build, and I can't picture many corporate types (other than Elon Musk, maybe), being willing to make such an long term investment. They mostly live and die by their quarterly profits after all.
i read somewhere that a single microscopic flaw in a carbon nanotube reduces the tensile strength by 70%. last i checked we couldn't make a bar of soap purer than 99.44. how long would such a project take? gotta be generations, right? how many millions of acres would the site for the base need to be? how would you displace the people living in that area? As pointed out already, it's not just the tech keeping an elevator from happening, it's the scale. this ain't happening any time soon. pipe dream (*rimshot).
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Damn, and I was wanting the contract to haul to the moon 
Great homework project, but there are some practical aspects that would cause difficulty. Perhaps they are mentioned in the literature, but I don't know.
One is that the Moon's orbit isn't perfectly circular. The eccentricity means that the distance to the Moon varies a bit. Also, the "face" of the Moon that faces the Earth wobbles around.
Another is that a rendezvous of a ship from the Earth at the "Liftport" would be significantly more challenging than a rendezvous with another spacecraft, as the ship will require a steady engine thrust to maintain position, whereas the "Liftport" is restrained by the elevator tether.
During the lunar night, there would be no solar power.
She mentions protection from meteoroid impact. That is not trivial. The JWST, located at L2, has already had impacts.
What I hope to see is a catapult of some sort (railgun or perhaps spin launch) to launch stuff off the surface of the Moon.
One is that the Moon's orbit isn't perfectly circular. The eccentricity means that the distance to the Moon varies a bit. Also, the "face" of the Moon that faces the Earth wobbles around.
Another is that a rendezvous of a ship from the Earth at the "Liftport" would be significantly more challenging than a rendezvous with another spacecraft, as the ship will require a steady engine thrust to maintain position, whereas the "Liftport" is restrained by the elevator tether.
During the lunar night, there would be no solar power.
She mentions protection from meteoroid impact. That is not trivial. The JWST, located at L2, has already had impacts.
What I hope to see is a catapult of some sort (railgun or perhaps spin launch) to launch stuff off the surface of the Moon.
Funkworks
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But when one cord isn't enough, I use 2. Or 3, or 10 ... or 1000, or ... does the article have numbers? Not extremely difficult to find out how many strands are needed once their tensile strength is known.
That's it? No reason why? I'm ok with starting a thread to find out more about Mars missions.
I agree but I mean for prototypes, it might be easier to make first tests elsewhere. I had never imagined a space elevator somewhere else but on Earth and thought it was a neat image, whether sci-fi or real.
What I do is I aim for the stars, and settle for a road trip.
Springs, dampers, etc. (of record-breaking sizes)
Not sure I understand. Is what you call a "liftport" on Earth or in orbit?
Grid-scale batteries of course. People don't seem to know about this little secret yet. Should be automatic: Solar? Grid-scale batteries! Wind? Grid-scale batteries! Power control? Grid-scale batteries! Power distribution? Grid-scale batteries! Power in space? Batteries! Power deep in the ocean? Batteries! Power stabilization? Batteries! Etc.
Not so bad so far: https://www.space.com/spinlaunch-aces-10th-suborbital-test-launch
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It's a 8 month trip there so you you need enough food water, and oxygen. Then once you get there you would need to leave as Mars and Earth only get close once every 2 1/2 years, then you need the previous things for the 8 month return trip, all in one spaceship. As one prominent scientist said, " the perfect suicide mission"
It is on the diagram at point B.
regarding mars and the moon, i can only imagine any extra terrestrial colony being built entirely by drones and AI. it's just irresponsible to send highly trained and invested humans to create a habitat where life isn't welcome. i imagine this would require a fleet of communication satellites, solar power arrays charging Niven batteries to fuel drones, and at some point, freefall space ports and habitats to progressively move people as needed. additionally, if you can build an elevator to the moon, you could also build a station at the end of the elevator that wouldn't require additional engineering to compensate for whatever evils the moon offers, as proposed by sr205347d.
No one is going to be launching grid scale batteries into space.
She didn’t say how fast the elevator would travel along the tether. But, assuming the average speed is 100 mph (pretty fast for an elevator), it would take 10 1/2 weeks to get from the lift port to the surface of the moon. I’d take the rocket the whole way.
Funkworks
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Every prominent scientist currently working on space and mars missions have known this since they were kids.
If it's the weight you're concerned about, remember a battery is short for a battery of cells. The bigger things can be built rather than carried as a whole. But you're welcome to check out the max lifting capacities of the heavier lifters.
Thanks.
These are all problems, but there is no reason to assume that no solution exists for them. A very obvious at least partial solution is to grow plants aboard the spacecraft to recycle the carbon dioxide into oxygen and provide food. The ISS has already demonstrated 93% recovery of used water. We may not be ready now, but as the various issues are retired, we may be ready for the Mars mission in the coming decades.
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If you are going to build a space elevator to the moon, wouldn't it be helpful for the moon to be over the exact same spot on earth, all the time in the exact same orientation? After all we are going to build a tether somewhere between 210,000 and 250,000 miles long. 18-20% of fudge in an engineering design seems to be worth consideration after we get the bodies to stay facing one another.....unless your connection is substantial enough to tie them together.
It would suck to be a contractor building this and being stuck out roughly 100,000 miles from the Earth's surface when the boss says the money is running out.
It would suck to be a contractor building this and being stuck out roughly 100,000 miles from the Earth's surface when the boss says the money is running out.
That is one of the reasons that the US would not do this. Unless, of course, they suddenly found a solid-gold asteroid or something that made the corporate/political eyes bug out.
Very true. That's why I said 'enormous'. The scale is enormous, the difficulty of making near-perfect nanotubes is enormous. The breakthrough(s) that would make a space elevator practical would be equally enormous.
But...consider the advances in silicon technology. Until zone refining was developed, about a century ago, silicon could be refined to about 99.9% purity. Zone refining brought six-nines purity. Today we require eleven-nines purity; that's equivalent to one particular person out of the entire population of earth. Still...I don't see a breakthrough coming any time soon.
The space elevator this student is proposing is based on the Moon, not the Earth, so the gravitational forces are much less and the strength of the tether is in the realm of "doable." However, that doesn't mean that her idea is practical. Construction would require all materials to be launched from the Earth to the L1 point, almost all the way to the Moon. This would be cost prohibitive. Then, in operation, any cargo destined for the Moon would still need to be launched from the Earth to beyond geostationary orbit. I see no practical benefit.
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I misunderstood/misread.
You do still have to get parts, people and/or robots, to the moon to start work, or at least all the parts for the factory (and the raw materials).
A few $billion per ton makes this a little daunting.
and 
JStarStar
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a "space elevator" will never ever work because if you had a cable or other connective device attached to some kind of anchor object, even assuming in theory the ground anchor was placed precisely on the equator and the orbital anchor was in a precisely geosynchronous orbit and the problems of minor orbital inconsistencies and eccentricities could be overcome (highly unlikely), your orbital cable would constantly be subject to impacts from other objects (ie space junk) in inferior orbits with relative speeds of several thousand mph to the cable, the cable could probably survive hits from stuff like paint chips and sand grains, the first time you hit a 2 meter long piece of metal weighing 100 kg, it's hasta la vista to your elevator cable. The cloud of space junk in orbits 200-500km would serve as a very effective guillotine for any "space elevator."
I thought the idea was that the orbital anchor was placed beyond geosynchronous orbit so it would be pulling on the tether, therefore would maintain tension in the tether even when a payload was climbing it. And tension in the tether could even out orbital inconsistencies.
Yes, you would need to do that. There's significant weight in the tether itself that needs to be counteracted/counterbalanced so obviously that can't be achieved by something in free orbital equilibrium. Yes, a fraction of that weight is countered with centrifugal force of the tether itself, but not all of it.
TP
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Funkworks
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My point is that any progress made to improve high-tensile strength materials like carbon nanotubes is great, regardless of whether they can reach space. The journey (improving materials) is more important than the destination (space elevator) yadda yadda yadda. I don't really care if we get there. It's a worthwhile direction.
Yeah you wouldn't want 30,000 miles of cable falling on your head.
The argument there is that such a facility would be built within a large exclusion zone (10, 20, 100 or more miles) beyond which the cable would be expected to burn up on re-entery.
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In S1:E1 of the series Foundation based on Issac Asimov's books the Starbridge, a space elevator, is destroyed by terrorists.
It would seem that if a section is destroyed some debris will fall while other parts would go into space from the loss of equilibrium, the gravitational field.
It would seem that if a section is destroyed some debris will fall while other parts would go into space from the loss of equilibrium, the gravitational field.
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