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LiftPort Wants To Build Space Elevator On the Moon By 2020
Zothecula writes "When the late Neil Armstrong and the crew of Apollo 11 went to the Moon, they did so sitting atop a rocket the size of a skyscraper that blasted out jets of smoke and flame as it hurtled skyward. For over half a century, that is how all astronauts have gone into space. It's all very dramatic, but it's also expensive. Wouldn't it be cheaper and easier to take the elevator? That's the question that Michael Laine, CEO of LiftPort in Seattle, Washington, hopes to answer with the development of a transportation system that swaps space-rockets for space-ribbons. LiftPort ultimately wants to build a space elevator on Earth, but the company isn't planning on doing it in one go. Instead, Laine and his team are settling for a more modest goal – building an elevator on the Moon by 2020. This is much easier. For one thing, there’s no air on the Moon, so no icing problems. Also, the lower gravity means that no unobtainium is needed for the ribbon. Kevlar is strong enough for the job. And finally, there’s very little in the way of satellites or debris to contend with."
That problem is that there is no way to create a lunar-centric orbit where the upper terminus of the ribbon hovers over a fixed position. So any tether can not be fixed to the ground. So lifting anything with that tether will involve something like a skyhook catch, except it will be at orbital velocities.
They're forgetting the single most important part of a space elevator: It needs to actually be useful.
What are we going to do with a space elevator on the moon? We don't go there for a very good reason: Its expensive as hell. Making the cheap and easy part a little cheaper an easier isn't going to change the fact that the entire rest of the trip is prohibitively expensive.
It's like your friend moving across town to be closer to you, but he lives in Seattle and you live in London.
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Wouldn't we need to get back to the Moon, establish some sort of colony there, and create the industry and infrastructure just to build such a thing in the first place? I can't see this all happening in the next 8 years.
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Well I'm not so sure... It would make transport on and off the surface cheaper. This would in turn make it more economical to conduct mining operations on the the moon--which is presently our easiest to access source of Helium-3.
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No, you hang it from a satellite that is in geostationary orbit around the moon. No lagrange point needed.
The moon rotates once every 28 days, not 24 hours. Too lazy to calculate the numbers, but I think a lunastationary orbit would have a ridiculously long radius. Not practical. Better do do what the GP suggests: put the upper part at Lagrange point.
There is some additional information in this article.
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They said Space elevator. Space elevator "orbiting the moon" are your words. This link shows exactly what they are attempting to do: http://www.gizmag.com/lunar-elevator/23884/pictures#2
The moon does not rotate. When you look at the moon the same side of the moon always points to the earth. So, the ribbon would need to be held stable by Earths gravity to some extent (it seems).
Our moon does rotate, with a period equal to its revolutionary period about the earth. This kind of synchronization is common with moons of planets, and is caused by tidal forces between the moon and the planet.
If it weren't for deadlines, nothing would be late.
My orbital mechanics sucks, but apparently smarter people have thought this through. It's not as intuitively simple as a tether between the Earth's equator and a geostationary satellite, but the physics does work:
http://en.wikipedia.org/wiki/Lunar_space_elevator
My issue is that this is yet another fancy space project that presupposes an earth to high-orbit launching capability we don't have, nobody is seriously working on, and would seem to require more financial support than anybody has the will to deliver.
If somebody can crack this nut, then we can start talking about lunar space elevators, missions to other planets, and other fun stuff. But until that happens, all these fancy proposals are just so much hot air.
A lunastationary orbit would have a radius of ~384400 km (the distance from Earth to the Moon).
If you put the upper point at L1 or L2, you'll still have to put an anchor farther out to keep tension on the cable. Which may or may not be really useful, but it's an interesting idea, anyway.
"I do not agree with what you say, but I will defend to the death your right to say it"
Space elevators also allow you to bring things gently DOWN from orbit. How's that mass driver gonna work for ya?
It could work quite well. Mass drivers can decelerate as well, and can recover and convert the kinetic energy to electricity in the process.
Except that it's not economical: all current plans for fusion power intend to breed the required fuel isotopes from lithium, which is several orders of magnitude cheaper than mining anything from space.
So, that leaves what? Nothing. There is nothing on the Moon even remotely worth the multi-trillion-dollar expense. It's just rocks in a vacuum. We've got plenty of rocks here!
Because catching a bullet with a gun is just as easy as shooting a bullet from a gun...
It's not for profit, because there's nothing worth lifting off the Moon.
It will not work as a proof of concept, because what we learn from it will not apply to a space elevator anchored on Earth.
Maybe I should elaborate on the this. The Moon rotates slowly. Remember, the same side always faces the Earth, thus its rotation period is the same as its orbital period. So for a space elevator to stay up, it would have to be quite long, anchored at an equatorial point facing Earth, and the higher end would have to be close enough to Earth for the forces to balance. (Attraction from Earth, attraction from the Moon, pull exerted by the string/rail...)
I am not a physicist, nor have I done the math. I do not even know whether the above setup is workable. But I do not believe that another setup is even remotely possible, and I do know that we would not learn much about building an elevator from Earth even if we built an elevator from the Moon in the above fashion.
Basically, I believe this is bullshit. Now that I have probably revealed my ignorance, I'll go and RTFA. Probably I'll learn that the summary's misleading.
No good deed goes unpunished...
"settling for a more modest goal – building an elevator on the Moon"
Did someone just use the words "settle" and "building on the moon" in the same sentence? Who are these people?
Where are the billions of dollars this is going to take? How the hell are they going to prototype it?
Do they realize that 2020 isn't some lofty far off time these days? That's a bit more than 7 years.
If NASA, Russia, or China (or Elon Musk) said they were going to try this, I'd be excited. But this shit is not going to happen like this, lets just be honest.
There's plenty worth lifting off the moon, if we can do it. There's water for starters, plus plenty of raw materials for making high quality metals, ceramics, semiconductors and so on. If you can send them into a low Earth orbit then you'll probably find you can beat the per-kilo costs of launching similar material from Earth, what with the big gravity well and atmosphere and all. If you can undercut an entire planet then I'd call that a worthwhile business opportunity. Can't see how a space elevator helps much, but there's plenty worth lifting off the moon.
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Correct, it's tidally bound to the Earth, you'd need to "anchor" it at, or beyond, L1.
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You put LiftPort on the front page and forget their KickStarter campaign?
It started on the 23.08, and in 5 days it's raised $27.514 of the 8000 goal.
http://www.kickstarter.com/projects/michaellaine/space-elevator-science-climb-to-the-sky-a-tethered
I'm a dreamer, the world is my playpen. But hey, I'm a serious person, I can't dream all the time.
He-3 is preferable for a fusion fuel since it's aneutronic--no radiation to deal. It comes that way from the moon, the path to producing it on earth does everything but avoid radiation.
Even the "aneutronic" fusion reactions have side-reactions that produce neutrons. While a lower neutron flux helps with materials engineering from a longevity standpoint, it still makes the reactor wall materials radioactive. That's the real problem, and He-3 doesn't fix it.
He-3 is useful as an advanced fuel in rocket propulsion
a) Requires technology that is currently at the wishful-thinking stage of development.
b) Rockets don't require aneutronic fusion, because fusion engines would be most useful in deep space, where radiation is not a problem.
c) He-3 fusion isn't entirely aneutronic anyway.
d) He-3 fusion is harder than D-T fusion.
Power can be produced in space and beamed down to earth
Has nothing to do with the Moon, or an orbital tether.
There is no realistic source of power that either exists only on the Moon, or would be cheaper to produce on the Moon.
Many of those rocks we have down here on Earth resulted from really big rocks from space slamming into us. Might be good idea if we have technology, infrastructure and humanity already in space before we're in need of it.
A tether on the Moon won't help you solve this problem. If this comes up, robotic space-probe technology will be all we need, and we have that already. Stop watching Hollywood sci-fi where brave men have to go deal with the problem in a giant space ship. The real solution will likely be as simple as coating one side of the incoming object with soot.
Putting multi-trillions of dollars into the vacuum is preferable to craters into the middle-eastern sand. The same jobs are created but at the end of the day at you have something far more impressive to show for it and far fewer lives expended.
[citation needed]
Things aren't that simple in the real world. As cold and sad as it is, the lives of brown people in a distant desert just aren't worth much to anybody in the United States, unlike the oil they live on top of. By some calculation it was worth it to invade. Thanks to various mistakes, the cost ended up spiralling out of control, but even so the wars are probably a better investment than going to the Moon.
He-3 is worthless, because it doesn't achieve aneutronic fusion, just slightly-less-neutronic fusion. So then, what's left on the Moon that's worth a multi-trillion investment?
Seriously, name one thing that's on the moon that you think is worth trillions of dollars, keeping in mind that its surface is entirely covered in rocks.
The mining machines wouldn't necessarily need to be: massive, transported via the tether, and/or come down fully assembled. Not everything has to start out on massive scales. For instance consider the state of global shipping back in the 18th century then compare that to the early 21st. Or farming in the 18th vs. 21st. Normally things start out small and gradually build out as technology and resources develop. Staging things is simply an engineering problem which if Curiosity is any indicator we seem to be getting pretty good at. Even during the Apollo missions we were dropping some pretty serious hardware down onto the moon. Powering these machines can come from any number of technologies from mundane to exotic. We already have well proven solar and RTG technologies, there are a few rather interesting possibilities using in-situ resources as well. For instance using the newly discovered water with the aluminum in the regolith to produce hydrogen for fuel. The Aluminum Hydroxide byproduct has its own interesting uses. The obvious one is of course simply using the mined He-3 for fusion power (whenever we get that one figured out).
Few grand adventures into human frontiers are ever "practical" initially and that unfortunately prevents people from seeing what humanity's pioneers and explorers see. In the 1800's no one got what Charles Babbage saw. During the first half of the 1900's very few saw what Konrad Zuse saw. Today no one can miss it and everyone demands it. People too often are quick to see problems as "too hard", too near-sighted to see possibilities, too self-centered to appreciate the benefits to others. You might not get to holiday on Utopia Planitia, or sail the methane seas of Titan but wouldn't it be awesome to initiate the projects now that make that a reality for your progeny? Both incomprehensible business opportunities and human delights await us on this next frontier. What are we waiting for?
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Liftport has been around for a while, but they've run into a number of troubles. I don't know what your age or life expectancy is, but if you take their roadmap seriously, it's quite possible that there will still be a space elevator in your lifetime.
Of course, if you take their roadmap without a pretty serious grain of salt, you probably haven't been following them for the last six or so years. It's been adjusted backward many times.
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L2 might work better as you could use the additional leverage to assist launching stuff out of cislunar space.
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Ya do realize planes manuvering to land on an aircraft carrier have wings and tails to take advantage of an atmosphere, and every tiny bit of manuvering to line up exquisitly precisely with your bullet-catcher is going to require fuel...
By definition a space elevator orbits whatever you attach it to. Otherwise, it falls.
By definition, a space elevator is in a super-orbit.That is, it's centre of mass is moving faster than the natural orbital velocity for the centre-of-mass' distance from the parent mass. It would move into a higher eccentric orbit (or escape) were it not for the application of a force in addition to gravity. Specifically being being attached to the ground by a insanely long cable. Which keeps the whole system stable, under tension.
Science is all about firing a drunk pig out of a cannon just to see what happens.
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It will certainly be a much cleaner, albeit hugely expensive, non-feasible fuel for the fusion reactors we won't be able to build in 2050 than the cheap and readily available non-feasible fuel we can't extract from ordinary seawater for the fusion reactors we can't build right now.
You are not a brain: http://books.google.com/books?id=2oV61CeDx-YC
It will not work as a proof of concept, because what we learn from it will not apply to a space elevator anchored on Earth.
The biggest issues to work around in most projects are the ones nobody thought of at the beginning. Even though many of the variables will be different for the moon vs Earth, it'll be useful to know that a) it can be done, and b) what the unexpected problems were.
William of Ockham had no beard. The most likely explanation is that it was chewed off by squirrels every morning.
Indeed, to be stable the elevator would have to be "stationary" within the rotating Earth-Moon frame, with the top extending past either the L1 or L2 point (towards or away from the Earth) far enough that the force of it "falling away" from the moon would be sufficient to counteract the weight of the cable itself.
Calculating the exact distance of the L1 and L2 points can be difficult, but so long as the masses are significantly different they are at approximately the Hills Sphere radius from the smaller mass M2 at r = R (M2 / 3*M1)^1/3. For the earth-moon system that is about 60,000km from the moon, versus the 36,000 km from Earth that constitutes geostationary orbit. So the elevator would have to be about 60% longer than on Earth, but the much lower gravity means it could be far thinner and weaker, and thus easier to build. Even perfect carbon nanotubes barely have the strength-to-weight ratio necessary for an earth-based elevator, with no room for a safety margin.
Plus for the immediate future at least the liability is much lower on the moon - a failure that drops 60,000 km of cable onto the moon from orbit is unlikely to be a problem beyond the fact that your very expensive elevator is now scrap. Drop 36,000 km of cable onto Earth, enough to to wrap almost all the way around the planet, and you're going to have a heck of a lot of secondary damage.
Personally I prefer the idea of the "tumbling cable" elevator - take just a few hundred kilometers of cable orbiting while tumbling end-for-end with the tips coming down almost to the surface like opposing spokes on a wheel rolling along the Moon's equator and you've got an elevator that will match speeds with various points on the equator on a regular basis, coming almost straight down before momentarily stopping and then hauling snagged payload up at roughly 1/4g. By the time the payload reaches it's highest point it will be moving sufficiently fast to easily escape the Moon's gravity, and depending on the particular orbital trajectories of the cable and Moon at the moment of release, moe than enough to escape the Earth's as well, even to put it on a Hohmann transfer orbit to Mars or Venus. Granted all that extra energy means it's not ideally suited to Earth-Moon transfers, but it sure would be a lot smaller and easier to build (except for the necessary drive system to recharge the angular momentum transferred to the payload), as well as making the Moon a major waystation to our much more interesting planetary neighbors.
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They had rocks in Spain too. After they conquered a new world, they had a lot more rocks. Shiny, pretty rocks.
Who needs speed? The elevator would still let you drop big rocks on Earth - sure they're moving slow relative to the top of the elevator when you let them go, but the entire moon is moving at about 1,000km/s relative to the Earth, and once those rocks have fallen the remaining couple hundred thousand kilometers to Earth they'll be moving even faster, more than enough to do massive damage wherever they're aimed. We *might* be able to shoot them down, assuming were willing to expend a space-capable nuke against it, were able to hit the thing given the massive speed it's traveling at (shouldn't be *that* hard to basically stand in it's path), and preferred to have radioactive slag come raining down over a wide area rather than letting the rock vaporize it's target. Of course if several rocks were dropped at once that would be far more difficult.
That's the one big problem with a space-based economy - once you're moving heavy stuff around in orbit *everything* becomes a high-yield weapon, and there's not much anyone on Earth can do to defend against it. It's like the ultimate version of trapping your enemy in a narrow canyon where you can fire down at them from all sides. And if an Earth-moon war should ever break out, well the Moon is almost guaranteed victory - both sides will see any incoming weapons a long way out with plenty of time to intercept - but hitting the Moon requires high-energy launches, while launching from the moon requires only ~1/25 the energy (~1/5 the escape velocity) so they can just throw rocks all day long for the cost of launching one missile, and any debris from intercepted weapons in either direction is far more likely to fall back to Earth than hit the moon.
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The problem with propulsion is that it must be continuous - shut down the engines for a couple hours and your billion-dollar elevator comes crashing down. As for a solar sail, the moon rotates relative to the sun so you can't get stable thrust that way, not to mention that the necessary forces would likely be far larger than could be attained. Solar sails are great for supplying continuous tiny thrust to small ships, given some highly reflective, ultralight unobtanium for your sail. Not so much for supplying the millions of Newtons necessary to hold up a thousands of km of cable. Far better to make your cable long enough that the far end falls up and can support the lower portions.
There's also the point that you'll need to lift your payload out of the Hills Sphere regardless, and the L1&2 points are conveniently stable points right on it's radius. Personally I'd go for capturing a moderate-sized asteroid as a counterweight just beyond the L1 point. Then you can burrow into the asteroid to create a heavily-shielded micro-gravity space-station as well, great for research, uG manufacturing, and tourism.
The other viable option would be the orbital wheel/tumbling cable style elevator, which could actually be quite well suited to the moons airless surface since it could come down almost to the surface, with a more dynamic tether that could adjust the last few km to perfectly match the surface elevation and snag things into orbit. it's more difficult to match orbital energies with Earth orbits that way, but quite easy to launch stuff directly from the Moon's surface on Hohmann transfer orbits to Mars or Venus with proper timing, and aerobraking lets you get stuff to Earth fairly easily. The biggest problem is it's a real challenge to catch the elevator in orbit to ride it down, so you probably end up not recapturing all that precious kinetic energy and need to equip it with larger engines to replace the kinetic energy transferred to the payload during "takeoff"
--- Most topics have many sides worth arguing, allow me to take one opposite you.
Seriously, name one thing that's on the moon that you think is worth trillions of dollars, keeping in mind that its surface is entirely covered in rocks.
Rocks in space.
Seriously, look at the price of titanium on earth - about $7 US per kg for commodity ferro titanium. Look at the price of titanium in low earth orbit - according to Wikipedia, it costs about $4300 US per kg using a Proton rocket (the cheapest non-subsidized launch method listed). There's quite a lot of titanium on the Moon, as well as aluminum, iron, and magnesium.
That's why we want to mine asteroids and the Moon - getting material out of the Moon's gravity well is a lot easier than getting it out of Earth's gravity well (and of course asteroids generally don't have an appreciable gravity well).
If we want a space station that's more than just a few tin cans glued together and can protect its inhabitants from radiation, we need building materials. We can get many of those materials from the Moon. We'd have to learn how to process and smelt them there first, of course, but you have to start somewhere.
He3? Well, maybe later. You don't build a gas station before the invention of combution engines. Water is more valuable, if it can be collected in any serious amount, which we still don't know.
That said, I have my doubts that anyone could put a space elevator on the moon in 8 years. It's just not going to happen. The design phase would take at least half that time.
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Unfortunately at 50ppb or less you will use more energy mining that you get out of it. That is assuming you have He3 fusion working which is many times harder than DT fusion which we still *don't* have.
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Only 2 really big problems with that idea.
.1ppb) its a square 50km a side. For just one year just for the US, on the moon!
One, there is almost no He3 on the moon, sure the ratio compared to He4 is massive... but that is not the same thing as a decent amount of He3. Its about 50ppb or less, the average is more like 1ppb. You would use more energy mining it that you get from the He3. Note this more than 1000 times more dilute that commercial quantities of Uranium.
The second big problem is that He3 fusion is ~50 times harder to do than DT fusion which we can't do! So even if you get some He3, you can't burn it. If we can do He3 fusion we can also do plain old DD fusion and save the trip to the mine on the moon.
Lets run a number or 2. The US uses just a little more than 3900 TWh of electrical energy per year. That is 14x10^21 J. Quite a bit. 1 mole (3g) of He3 fused gives us 614GJ . Se we need 7622kg of He3 per year at 100% efficiency. Now is that 50ppb by weight or not? i don't know and i will assume by weight (this is more conservative). The average is closer to 1ppb but lets see what we get at 50ppb. Assuming 100% extraction (totally unrealistic) we need to mine 153x10^9 kg per year. At 1ppb its 50x that, or more like 7650x10^9 kg (7600 million tons)! The he3 is only in the top layer. At 1 meter deep, that is an area of 50x10^6 meters, or a square about 7km on each side. With closer to true average levels of 1ppb (some papers even claim as low as
We won't do it. We will just use DD fusion where the fuel is readily available from water right here...
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