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."

Comments

The goal of the project?

[Anonymous Coward]

If it's for profit, how does it make money?
If it's not, is the point to prove it's possible and learn more about how to build one?

Re:The goal of the project?

[neminem]

I assume the latter. I mean, when I'm programming a new component, I often start with the easier component while I'm figuring out the harder stuff, even if the harder stuff could be useable by itself and the easier stuff requires the harder stuff to work (at which point I would just put up a placeholder for testing purposes). Granted, I'm talking about days of one developer's time rather than years of a whole company's, but the principle is similar. Once you had a terrestrial space elevator, you'd want a lunar one too, so might as well practice on the easy target first.

But yes, I was also depressed, when I just saw "[company] wants to build space elevator by 2020", and missed the "on the moon" originally. I was all excited that we might actually see a useful space elevator in my lifetime. (Useful in this case being defined as "would let me exit earth's atmosphere at the cost of less than a bajillion dollars per trip.")

Re:The goal of the project?

[Tuidjy]

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.

Re:The goal of the project?

[History's Coming To]

I would imagine so, I can't think of a "killer app" that isn't easier to do with an electromagnetic mass driver, and for exactly the same reasons (near vacuum, low gravity), except for possibly the power requirements.

Re:The goal of the project?

[History's Coming To]

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.

Re:The goal of the project?

[Anonymous Coward]

If it's for profit, how does it make money?
If it's not, is the point to prove it's possible and learn more about how to build one?

The point is to keep moving money from the enthusiastically gullible to Michael Laine.

Re:The goal of the project?

[slacka]

Why are they asking for money on kickstart, when they could save a ton just by switching from helium to hydrogen weather balloons? Sure they have to take some extra precautions because it's flammable (NOT explosive, google it) , but the cost saving will more that make up for it. In addition they are helping to preserve a precious resource necessary for things like MRIs.

Re:The goal of the project?

[cbhacking]

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.

Re:The goal of the project?

[Jahf]

3He will power the world!

Re:The goal of the project?

[jamstar7]

I would imagine so, I can't think of a "killer app" that isn't easier to do with an electromagnetic mass driver, and for exactly the same reasons (near vacuum, low gravity), except for possibly the power requirements.

The 'kicker' of course is that an elevator can't launch heavy rocks at high speeds the way a mass driver can. This protects the Earth from possible terrorrorrorrist takeover of any prospective catapult.

Re:The goal of the project?

[lennier]

3He will power the world!

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.

Re:The goal of the project?

[mooingyak]

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.

Re:The goal of the project?

[camionbleu]

It's not for profit, because there's nothing worth lifting off the Moon.

How about bags of helium (he said, in a very high-pitched voice)?

Re:The goal of the project?

[Immerman]

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.
 

Re:The goal of the project?

[Immerman]

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.

Re:The goal of the project?

[delt0r]

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.

Re:The goal of the project?

[Patch86]

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.

Well there's kind of problem number 2 with this business plan. Building a space elevator on Earth is attractive because the cost of rocket fuel to lift payload into Earth orbit is very large- a space elevator there for pays for itself over time, as once it's built the lifts are "free".

Same problem doesn't apply to the Moon. Lifting things from the lunar surface is already cheap and easy in terms of conventional rocketry due to the weak gravity and no atmosphere. So although the space elevator is easier to build, the payback is much smaller.

If we wanted to lift material from the Lunar surface into orbit, we already could- that's the easy bit. But the other bits (finding something worth lifting, building mines to extract it, etc.) haven't come together, so we've never bothered.

Re:The goal of the project?

[micahraleigh]

The commercial value of water is extremely low. As in "It's free at restaurants" low.

Re:The goal of the project?

[History's Coming To]

OK, in that case pop down to your local restaurant, get a free glass of water from them and send it to the ISS. Tell us how much it cost to give an astronaut a free glass of water.

The point is that free stuff isn't free once you've launched it to orbit. Doesn't matter how cheap a kilo of $cheap-substance costs, you still need money to get it into orbit. A kilo of dirt from your back yard? $10k. A litre of free water? $10k. A kilo of diamonds? Whatever the diamonds cost, plus $10k.

Re:The goal of the project?

[Forty Two Tenfold]

How about bags of helium (he said, in a very high-pitched voice)?

Nope. You can't get helium to Earth's surface. It's lighter than air!

Re:The goal of the project?

[History's Coming To]

Precisely. To get from the Earth to the Moon you need a Saturn V. To get from the Moon to the Earth you need an Apollo LM Ascent stage.

Re:The goal of the project?

[micahraleigh]

Just because it costs $10k to put a kilo (whatever that is) of dirt from my backyard into orbit, doesn't mean people can make money doing it.

The question was: "If it's for profit, how does it make money?"

If it's just to give the astronauts a drink, it is not profitable to build a space elevator on the moon.

Space elevator orbiting the moon?

[Ken_g6]

First post? Anyway, you can't "anchor" a space elevator to the moon from lunar orbit. It would have to stretch all the way to the Earth - or at least to a Lagrange point.

Re:Space elevator orbiting the moon?

[Anonymous Coward]

No, you hang it from a satellite that is in geostationary orbit around the moon. No lagrange point needed.

Re:Space elevator orbiting the moon?

[Nadaka]

The moons rotational period is its orbital period. There is no orbit around the moon that is "geosynchronous".

Re:Space elevator orbiting the moon?

[Anonymous Coward]

The moon doesn't rotate much (every 28ish days). So your object won't have much velocity. And if it's basically just sitting out there, barely orbiting, the Earth's gravity is going to yank it all over the place.

I think a luna-stationary orbit might be harder than it looks.

Re:Space elevator orbiting the moon?

[ClickOnThis]

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.

Re:Space elevator orbiting the moon?

[Time_Ngler]

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

Re:Space elevator orbiting the moon?

[randall77]

The upper point needs to be beyond the Lagrange point in order to hold up the elevator. Probably well beyond, depending on its mass relative to the cable.

Re:Space elevator orbiting the moon?

[CrimsonAvenger]

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.

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.

Re:Space elevator orbiting the moon?

[Nethemas the Great]

It "might" require an anchor at L1 or L2. We're not used to thinking of building tethers that long and so it seems silly but I'm not sure it's quite as impractical as it sounds. It's just a matter of weaving fibers together until desired length is achieved. Why I say "might" though with respect to needing to anchor at L1 or L2 is that I can see alternatives that compensate. To my understanding all that is required is the ability to hold the tether taut. This can be achieved with length, anchor mass, or I would suggest possibly propulsion. A reaction engine could be used that uses the very aluminum harvested from the regolith as fuel. Or, potentially a solar sail could be used that would effectively turn the anchor into a solar kite.

Re:Space elevator orbiting the moon?

[Aviation Pete]

No, you hang it from a satellite that is in geostationary orbit around the moon. No lagrange point needed.

Make this "lunarstationary orbit", and you are correct.

Re:Space elevator orbiting the moon?

[Anonymous Coward]

Huh?

If you hang the thing from an orbiting satellite, the cable will drag the satellite back to the surface. It's heavy.

Space elevators don't hang. They use a weight being swung around using the body's rotation, and the weight is, by necessity, a long way the other side of the X-stationary orbit.

Re:Space elevator orbiting the moon?

[History's Coming To]

Correct, it's tidally bound to the Earth, you'd need to "anchor" it at, or beyond, L1.

Re:Space elevator orbiting the moon?

[Anonymous Coward]

WTFV. That is exactly what they propose to do. The upper end would be at L1.

Re:Space elevator orbiting the moon?

[symbolset]

Correct. This would work on 1 Ceres though. I was trying to figure the math on that one a few months ago.

Re:Space elevator orbiting the moon?

[Zordak]

Two of my imaginary friends reproduced once ... with negative results.

I'm confused. Wouldn't the result be positive?

Re:Space elevator orbiting the moon?

[symbolset]

L2 might work better as you could use the additional leverage to assist launching stuff out of cislunar space.

Re:Space elevator orbiting the moon?

[cyborg666]

If you anchor the elevator on the far side, wouldn't it be "flung out" by the motion of the moons orbit, thus reducing the lunarstationary radius?

Re:Space elevator orbiting the moon?

[ClickOnThis]

Two of my imaginary friends reproduced once ... with negative results.

I'm confused. Wouldn't the result be positive?

Replace "reproduced" with "multiplied" and it might be a bit clearer.

Re:Space elevator orbiting the moon?

[__aaltlg1547]

Screw that. Just build a mass driver. Wont help you land though.

Re:Space elevator orbiting the moon?

[__aaltlg1547]

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

By definition a space elevator orbits whatever you attach it to. Otherwise, it falls.

Re:Space elevator orbiting the moon?

[Time_Ngler]

A space elevator cannot orbit what it's attached to. Otherwise, it's not in "orbit".

Re:Space elevator orbiting the moon?

[FatLittleMonkey]

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.

Re:Space elevator orbiting the moon?

[FatLittleMonkey]

Pedantically (which is all I seem to be doing lately), the anchor would be beyond L1/L2. There needs to be enough mass past the stationary orbit to balance the weight of the down-cable, and the payloads, plus a bit more to keep the system under tension.

Re:Space elevator orbiting the moon?

[tmosley]

So if I attached the moon to the Earth with a string, the moon would no longer be orbiting the Earth?

Astonishing!

Re:Space elevator orbiting the moon?

[ClickOnThis]

If you anchor the elevator on the far side, wouldn't it be "flung out" by the motion of the moons orbit, thus reducing the lunarstationary radius?

There's another Lagrange point on the far side of the moon known as L2. The short explanation is that any object at L2 does have a tendency to get "flung out" but the gravitational force from the earth and moon balance that out. As long as the object stays at L2, it orbits with the same period as the moon.

Re:Space elevator orbiting the moon?

[MDMurphy]

As the earth rotates approx 28 times the rate of the moon's orbit, said string would be winding around the earth like a spool. So either the string will break as the attachment point on the earth moves away, or given infinite strength it will reel in the moon to impact in approx 9 days.

So if the imaginary string is fragile it will snap. If it's sufficiently strong then no, the moon would no longer orbit the earth.

Re:Space elevator orbiting the moon?

[rossdee]

The problem with that is that the Earth rotates (in angle) faster than the moon orbits. Thus the string would end up being wound up around the equator (and pull the two together (assuming and infinitely strong string and anchor points...

Re:Space elevator orbiting the moon?

[MDMurphy]

The only way I can see that working out mathematically is that their offspring ate them both.

Re:Space elevator orbiting the moon?

[Zordak]

Well, yeah, but j^2 is -1 so ... yeah, the .sig makes perfect sense and I was thinking -1^2 instead of j^2 and I'll just go back to my motion for summary judgment after handing in my BSEE. (*HEAD WHACK*)

Re:Space elevator orbiting the moon?

[Immerman]

That "outward fling" (due is exactly what you want - you need to counteract the pull of the moons gravity on all the cable below that point. As CrimsonAvenger points out though the "lunarstationary" orbit is comparable to the Earth-Moon distance - it can be found for any body as r = (GM/w^2)^(1/3), which due to the slow rotation is approximately 300,000 km for the Moon - almost equal to the Earth-Moon distance and FAR greater than the Hills Sphere radius of ~60,000 km which determines the lagrange points as well as the maximum distance a satellite can orbit an astronomical body rather than its primary (Earth in this case)

Basically for a stable "beanstalk" style elevator to from the moon you'd have to extend through the L1 or L2 point to keep everything in tension. You have the choice of either extending a large distance past the point so the acceleration is large enough to generate significant force, or to suspend a large mass such as a captured asteroid only slightly past the point - just so long as the total outward forces are sufficient to balance the moonward weight of all that cable. Nothing you do will effect the distance of the Lagrangian point where the forces perfectly balance though.

Re:Space elevator orbiting the moon?

[Immerman]

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"

Re:Space elevator orbiting the moon?

[Anonymous Coward]

Turn in your geek card. i is an imaginary number representing the nonexistant square root of negative one. i times i is negative one.

Re:Space elevator orbiting the moon?

[DMUTPeregrine]

So put the string's anchor on a big track at the equator.

well that's just silly

[swell]

don't you think?

Re:well that's just silly

[Nethemas the Great]

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.

Re:well that's just silly

[swell]

"make it more economical to conduct mining operations on the the moon"

OK, but I'm having difficulty imagining massive mining machines working their way along the tether. And how to begin the process from an orbiting craft. And then, once landed, how will these machines get the energy necessary for mining operations?

I'm obviously missing some essential information about why this might be practical.

Re:well that's just silly

[bertok]

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!

Re:well that's just silly

[Nethemas the Great]

Similar ideas were had about computers and a great many other things. Sometimes the destination is a bit farther from you than your myopic vision permits to be seen. I also didn't say "economical" relative to earth bound alternatives but then you're also making the assumption that we're taking this stuff back to earth. Let's throw a few points up that you might not be considering:

• 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.
• He-3 is useful as an advanced fuel in rocket propulsion
• Power can be produced in space and beamed down to earth
• 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.
• 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.

Re:well that's just silly

[joe_frisch]

The reason that the elevator can work without unobtainium is that its EASY to get off the moon. The delta-v required is withing the range of all sorts of technologies (rockets - don't even need H2, could probably use O2 or N2 exhaust), mass drivers, etc.

This project would be insanely expensive - need to get the elevator (still a multi-thousand km structure) to the moon, set up etc.

Insane to think it could be done in 8 years.

Once you've done all that, there just isn't that much you really want from the moon. He3 is a somewhat better fusion fuel than D-T, but we are still at least several decades and several 10s of billions of dollars (probably MUCH more) away from fusion.

Re:well that's just silly

[Anonymous Coward]

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!

Using lunar material for construction projects in space is MUCH easier than getting any significant quantities from the deep well Earth is in.

Example projects:
* ridiculously large & light zero-g free-floating solar arrays with uninterrupted sunlight
* space habitats & manufacturing plants
* spaceships

Re:well that's just silly

[Anonymous Coward]

It would be much cheaper to get stuff from the Moon to the ISS than from Earth. If it became feasible to extract water from the Moon that could be enough to justify it.

Re:well that's just silly

[bertok]

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.

Re:well that's just silly

[Nethemas the Great]

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?

Re:well that's just silly

[Nethemas the Great]

Forming those rocks into a stepping stone.

Re:well that's just silly

[Nethemas the Great]

Have you considered the idea of a "prototype"? Just because it isn't the most needed place to set up an elevator doesn't make it useless. There are plenty more resources on the moon than simply He-3 for fusion as well and none of it needs to be hauled back down earth's gravity well to be useful. The manufacturing potential from the materials found on the moon--aluminum, silicon, magnesium, iron, and titanium to name a few--is huge. Why waste enormous sums of money launching your space-bound infrastructure out of earth's gravity well when it can be made on and launched from the moon? Launch circuit boards from earth, launch space frames from the moon.

Re:well that's just silly

[Anonymous Coward]

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.

1. Rare Earth elements.
2. (Potentially) Clean water
3. Raw materials that are in limited supply on earth, e.g. Copper

Then there's the thing about the Moon pulling away from Earth so actually reducing its mass by mining might not be a bad thing. Yes, right now in our current economic climate, going to the Moon for stuff sounds a little wasteful, but long term it will be done and the sooner we start planning for it the better. Would you have said something similar in the 17th or 18th century, "There's no need to go to America we have plenty of land and rocks right here in Europe!" Why so angry?

Re:well that's just silly

[Anonymous Coward]

Wouldn't the Nazis shoot it down anyway ?

Re:well that's just silly

[complete loony]

Reaction mass.

If we're going to send more probes / spaceships out into the universe, collecting reaction mass from the moon would be more energy efficient than lifting it from the earth. Even if we can't use that mass directly as an energy source.

Re:well that's just silly

[FatLittleMonkey]

I think you've missed bertok's point.

He3 is a waste product from D-D fusion. And D-D and D-T fusion are much easier than He-3 fusion. So if we ever achieve commercial He3 fusion, we'll have already had D-D fusion for decades. And since He3 fusion requires higher temperatures/pressures (ie, better confinement), the same technology would make D-D and D-T fusion more efficient/compact. Which means that even as He3 fusion displaces D-D/D-T for big power-stations, they'll move into entirely new markets (such as mobile power plants. Ships/etc.) And the process repeats, each time you improve He3, you improve D-D/D-T fusion even more.

But it's more than that. If we have fusion, it would be massively useful in space. So if we have the infrastructure on the moon necessary to mine the extremely trace amounts of He3 from the regolith, we'd have a lot of fusion power plants on the moon. And He3 is a waste product of D-D fusion...

So even after Earth bans D-D fusion, it would be cheaper and easier to do anything else in space and just export the He3 waste from their own fusion plants, than to mine He3 from the regolith.

He3 just isn't a reason for going to the moon. (And I say this as a space fanboi.)

Re:well that's just silly

[mattr]

- Real estate covered in solar flux = energy
- Temperature differences = energy
- A shallow gravity well = easy to ship things out
- Low gravity may = easier life for those weak due to medical conditions = retirement
- Dark side = potential astronomy sites
- As closest planetary body from which vacuum based engineering such as asteroid mining and space habitats could be tested and based.
- Close enough that robotic operations can be monitored and directed in real time
- Far enough that it is a good place for dangerous things like reactors, super particle accelerators and self-assembling nanolife construction bots.

Re:well that's just silly

[rossdee]

Yeah, I don't see the point. The moon has a lower escape velocity and no atmosphere. Lunar material can be put in orbit with a catapult. (Just make sure the free luna movement doesn't take it over.

Re:well that's just silly

[Anonymous Coward]

Wouldn't the catapult not fire as well on the moon?

Re:well that's just silly

[tmosley]

They had rocks in Spain too. After they conquered a new world, they had a lot more rocks. Shiny, pretty rocks.

Re:well that's just silly

[Anonymous Coward]

Don't pull the "some people were.wrong about computers" shit. You figure out multi-trillion benefits out. In detail. Then we can start even thinking about it. It doesn't work the other way around.

Re:well that's just silly

[bertok]

Forming those rocks into a stepping stone.

To what? More rocks?

Re:well that's just silly

[Anonymous Coward]

Ok, we'll go to the moon when we need reaction mass like that. Next.

Re:well that's just silly

[bertok]

1. Rare Earth elements.
2. (Potentially) Clean water
3. Raw materials that are in limited supply on earth, e.g. Copper

All three are available here, at 1/1000th of the cost, right now. Rare earth metals aren't that rare, water is everywhere and at most needs desalination, and copper is both easy to obtain and easy to recycle.

You would have to propose non-physical magic technology to enable any of those things to be shipped from the Moon to the Earth cheaper.

Re:well that's just silly

[bertok]

Assumes too much about future technology which doesn't even exist yet.

For example, ion drives are the best developed for deep-space exploration, and require only relatively small quantities of exotic substances such as mercury or xenon. Lifting a few tons of either into orbit is not a problem, and way cheaper than lifting an entire refinery all the way to the Moon!

Re:well that's just silly

[Anonymous Coward]

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.

Cheese. Duh.

If only 1% of the roughly 7,000,000,000,000,000,000,000 kg is useable cheese, given that cheese on earth costs something like 5 dollars per kg at the very cheapest end of the scale... there's an unimaginably large amount of money to be made through lunar cheese mining.

The moon is still believed by astronomers to be made of green cheese, right?

Re:well that's just silly

[bertok]

- Real estate covered in solar flux = energy

We have solar flux and real estate here, at 1/1000th the cost.

Also, energy THERE is not as good as energy HERE.

- Temperature differences = energy

There are no significant temperature differences that can be exploited, and no cooling water or air either. You're thinking of the temperature swing between the day and night side.

Also, energy THERE is not as good as energy HERE.

- A shallow gravity well = easy to ship things out

So what? There's nothing there worth shipping anywhere. It's just rocks.

- Low gravity may = easier life for those weak due to medical conditions = retirement

Doubtful. All evidence collected so far indicates that it would make things worse, not to mention the huge risk of living on the Moon and the drop in the quality of life. There's no parks and stuff outside to take a stroll in on a nice sunny day!

- Dark side = potential astronomy sites

Idiotic beyond belief. It's no darker than anywhere else -- it's just a name for crying out loud. Space telescopes are placed into orbit or Lagrange points for a reason: no vibration, no gravity, minimal temperature variations, and 24/7 seeing. The Moon has none of those things.

- As closest planetary body from which vacuum based engineering such as asteroid mining and space habitats could be tested and based.

You can do vacuum based engineering in Earth orbit, which is far more convenient. Not that this has been shown to be useful in any way, because we can produce vacuums down here on the surface just fine. What we can't produce is microgravity, which Earth orbit has, but the Moon does not.

- Close enough that robotic operations can be monitored and directed in real time

Just because it's practical to do things there doesn't actually provide a reason to be there. Not to mention that the 3 second round-trip delay makes "real time" a bit of a stretch.

- Far enough that it is a good place for dangerous things like reactors, super particle accelerators and self-assembling nanolife construction bots.

Nuclear reactors have killed fewer people in their entire history than coal mining has this year alone. Particle accelerators aren't dangerous at all. Nanolife is wishful thinking.

Also, energy THERE is not as good as energy HERE.

Got any ideas that belong in reality instead of fantasy?

Re:well that's just silly

[Nethemas the Great]

You know, I've really got to wonder what your arguments might have been back in 1492...

Re:well that's just silly

[Anonymous Coward]

Wouldn't the inhabitants of the hollowed out moon be pissed off?

Re:well that's just silly

[spauldo]

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.

Re:well that's just silly

[pantaril]

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!

If you start thinking outside of the box, that everything we mine in the space must be hauled and used back on Earth, then you will find out that access to metals/water/fuel etc. outside of the Earth gravity well could be very desireable and economical for constructions of e.g. moon base, orbital dock and subsequent space ships for interplanetary travels etc.

Re:well that's just silly

[delt0r]

Only 2 really big problems with that idea.

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 .1ppb) its a square 50km a side. For just one year just for the US, on the moon!

We won't do it. We will just use DD fusion where the fuel is readily available from water right here...

Re:well that's just silly

[Anonymous Coward]

There was a paper presented at the Space Elevator Conference in Seattle that dealt with the economics of mining enough Helium-3 (on the moon) to replace 1/2 of world-wide fossil fuel consumption. If Earth-based Space Elevators were available, the estimated cost of the lunar mining operation would be less than 10% of the cost to build the fusion reactors. Without the Space Elevators, the cost of the mining operation would be about 60% of the cost of the reactors, because of the use of rockets.

The estimated time to carry all of the equipment to the moon and set it up is about 30 years (this can vary, depending on how many Earth-based Space Elevators are used). The value of Lunar Space Elevators, in this case, would be to (1) reduce the fuel that needs to be hauled up the Earth-based Space Elevators for the Space Vehicles that travel between the Earth and moon, and (2) reduce the time required to implement the entire project.

Re:well that's just silly

[lennier]

* ridiculously large & light zero-g free-floating solar arrays with uninterrupted sunlight

Which use that power to do what?

* space habitats & manufacturing plants

Which manufacture what, and send it where?

* spaceships

Which go where?

The big problem I see with space construction and habitation is bootstrapping: space construction makes sense once you have a big population in space, and space habitation makes sense once you have a lot of space construction to get done, but there's no fundamental point to all of it in the first place. It's like how the Space Shuttle was designed to get modules and people to the Space Station, which was designed to be serviced by the Space Shuttle, but the two of them together didn't actually have a reason to exist.

In the commercial world, this level of investment without ultimate return doesn't really happen. The big driver of space tech in the last 50 years has been military needs: the requirement to set cities we don't like on fire within 20 minutes, and then to take spy pictures of the other side's city-setting-on-fire facilities... and even going to the moon was a small clip-on hanging off the side of that whole military infrastructure. And yes, even Silicon Valley and the Internet were tiny byproducts of that huge flow of military money.

But it seems to have turned out that even having a manned base on the moon isn't even really that useful militarily, let alone paying its way commercially. It might yet happen, like Scott Base at Antarctica; but there aren't even penguins at Tranquility Base, so how many dead rocks are underfunded scientists and bored tourists going to pay to catalogue?

Teleoperated moon rovers I could see happening; they're relatively cheap and safe to launch. Fully manned presence? Hmm. Let me figure the health and class-action lawsuit insurance bills for that. Not seeing the upside yet.

Just build it horizontally

[ShanghaiBill]

The Earth has an atmosphere, so a space elevator needs to go up to get out of it. On the Moon, there is no atmosphere, so the you can just build a mass driver horizontally, along the ground, and launch stuff in a tangential trajectory.

Re:Just build it horizontally

[LurkerXXX]

Space elevators also allow you to bring things gently DOWN from orbit. How's that mass driver gonna work for ya?

Re:Just build it horizontally

[Bill, Shooter of Bul]

True, but there are mountains and craters and other geological things that need to be avoided. Its not like its a perfect marble.

Re:Just build it horizontally

[ZombieBraintrust]

No sure how a space elevator is going to bring something gently down assuming the object was launched at the moon from the earth. Your going to have to slow down quite a bit to dock with an elevator. Might as well use that energy to land on the surface. Plus you run the risk of damaging the elevator if you attempt to dock things with it.

Re:Just build it horizontally

[randall77]

Non-uniformity only helps you, as you can take advantage of it to orient your mass driver above horizontal. The problem with a mass driver is the generated orbit intersects the moon again quite quickly (unless you go for escape velocity?). You need to redirect the payload once it is launched, with its own rockets or some sort of catching mechanism.

Re:Just build it horizontally

[ShanghaiBill]

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.

Re:Just build it horizontally

[monkeythug]

Get the trajectory just right and maybe you could 'catch' the object in the end of the catapult and slow it down using the electromagnets in a manner similar to the regenerative braking used in electric cars?

Re:Just build it horizontally

[randall77]

Because catching a bullet with a gun is just as easy as shooting a bullet from a gun...

Re:Just build it horizontally

[Anonymous Coward]

And get the trajectory just a bit not right and things gets messy!

Re:Just build it horizontally

[Anonymous Coward]

I think an aircraft carrier is a better comparison. The vehicles involved have some intelligence and control unlike bullets.

Re:Just build it horizontally

[Mycroft_VIII]

Yep real good for launching grains and such from the lunar colonies, as long as you have a decent computer to run the whole thing.
      Though if you use convict labor things could get interesting.

Mycroft

Re:Just build it horizontally

[LurkerXXX]

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...

Re:Just build it horizontally

[jamstar7]

Yep real good for launching grains and such from the lunar colonies, as long as you have a decent computer to run the whole thing. Though if you use convict labor things could get interesting. Mycroft

I see what you did there, tovarisch.

Re:Just build it horizontally

[Anonymous Coward]

And get the trajectory just a bit not right and things gets messy!

isnt the exact same true for docking with the elevator?

Re:Just build it horizontally

[randall77]

Yes, except substitute "aircraft carrier" with "maybe a 1m target" and "landing at 100mph" to "entering at 5400mph" (the escape velocity of the moon, a reasonable order-of-magnitude guess) and "miss and you lose an aircraft, maybe damage the ship a bit" to "miss and you blow your mass driver to smithereens".

Re:Just build it horizontally

[Immerman]

Yeah convict labor would be really stupid. In fact given the immense tactical advantage of a few hundred thousand miles of high ground with an unobstructed view we'd best make sure we never give the Lunies any reason to attack Earth. (Sorry, sorry, I meant Lunar Citizens. Please don't vaporize my city...)

Re:Just build it horizontally

[Anonymous Coward]

Docking can be done at speeds that cause dents, instead of speeds that cause holes or vaporization. If you were going to land on the Moon at such speeds, you've already done the hard work and don't need a catching device anyways. If docking somewhere near the middle, at least you don't need to use rocket fuel to get rid of the energy you would gain by falling into the Moon's gravity well. It would be far easier to extract electrical energy from the elevator descending in that case.

Re:Just build it horizontally

[Anonymous Coward]

If the elevator extends to or beyond the Lagrange point, then Earth's gravity can do all the deceleration work for you before docking. Going to the surface means working against the Moon's gravity.

Re:Just build it horizontally

[Anonymous Coward]

Without an atmosphere you can't manoeuvre to align yourself using wings, flaps etc. So you'd have to do it entirely on thrusters which'd use up fuel, especially the amount of thrust that'd be required to adjust yourself fast enough given the speed you'd be travelling.

It's far more likely you'd be off by half a meter (and with no possibility of turning around for another pass), which'd be enough for you to plough into the end of the mass driver's tunnel at several thousand miles an hour, killing you, destroying your craft and cargo, and damaging the mass driver severely enough to put it out of commission for months.

Re:Just build it horizontally

[Anonymous Coward]

We can build bridges and tunnels easily. Trivial compared to what we'd be building. What's the problem?

Re:Just build it horizontally

[Cormacus]

TANSTAAFL.

Do these guys work for Lexmark?

[Anonymous Coward]

So, we'll build a space elevator on the Moon, See?

And we'll only charge $49 for the entire elevator ride, and only $1M for the trip there, See?

But the return trip fuel cartridges will be $1M a piece, and they'll need THREE OF THEM!

There is one problem...

[Nadaka]

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.

Re:There is one problem...

[MozeeToby]

Which, at least in my opinion, makes it not a space elevator at all. After all, we could probably make a ribbon strong enough for an ultra sonic sky hook today or at least quite soon. A space elevator is a completely different ballgame. Using misleading buzzwords to get your funding off the ground is a bit of a red flag IMO.

Re:There is one problem...

[Anonymous Coward]

Yes there is. Since the same side of the moon always points toward the Earth , you could elevate the ribbon dead center on the "visible moon" and if it stretched high enough it could be drawn by Earths gravity into stability.

Re:There is one problem...

[ClickOnThis]

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.

Actually a Lagrange point would do fine for that. L1 is about 58,000 km from the moon towards the earth.

Re:There is one problem...

[Nadaka]

I hadn't considered that, it isn't strictly a lunar orbit.

And the length of cable would actually be as long as or longer than the cable required for an earth-geosynchronous orbit elevator (~36,000 km)

Re:There is one problem...

[wonkey_monkey]

Since the moon is tidally locked to the Earth, does that mean the geostationary point would have to be at an Earth-moon distance? Or do you mean that the moon's rotation is so slow that there is literally no "geo"stationary orbit above the moon?

Re:There is one problem...

[ClickOnThis]

I hadn't considered that, it isn't strictly a lunar orbit.

And the length of cable would actually be as long as or longer than the cable required for an earth-geosynchronous orbit elevator (~36,000 km)

As others have pointed out here, it would need to be a bit longer still and with a mass at the end, in order to maintain tension on the cable.

Re:There is one problem...

[david.given]

Having read TFA, this seems to be precisely what they're doing; it looks like they deploy at the L1 point and extend the tether in both directions. Of course, this does mean the tether needs to be an extraordinary 250000km long.

Despite being totally awesome (which is reason enough to do it!) and also good practice for Earth (ditto) I am slightly at a loss as to how useful this would be. Space elevators are slow, and a lunar elevator would be really long and therefore really slow. And it's not as if the moon's hard to land or take off from.

I'm wondering if there's something useful to do with the other end. The high end of the tether is only 135000km from Earth. Is that far enough into the ionosphere to use for power generation?

Re:There is one problem...

[Nadaka]

I mean that there is no geostationary orbit within the moons hill radius. And orbits do not exist outside an objects hill radius, things outside the hill radius by definition orbit something else or are on a non orbital trajectory.

Re:There is one problem...

[Score Whore]

And where is the counterweight going to go in case of an accident that severs the elevator?

Re:There is one problem...

[david.given]

I'm sorry, I don't follow you. Sever the elevator where? What are you expecting to happen/not happen?

Re:There is one problem...

[Anonymous Coward]

The high end of the tether is only 135000km from Earth. Is that far enough into the ionosphere to use for power generation?

The upper part of the ionosphere, the plasmasphere, extends up to 10,000-20,000 km (the plasmapause), where it cuts off abruptly. The actual altitude depends strongly on the magnetic latitude - it's much lower nearer the poles - and on the time of day. Source: Gallagher et al. (1988).

A few caveats, though. First, is there any reason why you can't extend the cable to lower altitude? It'll increase the tension a bit, but it's not going to fall as long as it's attached to the moon. Second, do you actually need to interact with the ionosphere to generate power? Don't you just need a conductive cable moving through the earth's magnetic field?

Re:There is one problem...

[canadiannomad]

Well isn't that the problem? *If* you have a lunar stationary space elevator and the cord were to snap, where would the counter weight go? And how big would it be?
Would it be pointed towards earth? Would it head off into deep space? Would it burn up? Would it be too small to worry about? Would it destroy a building? Cause a tidal wave? What?

Re:There is one problem...

[Anonymous Coward]

The counter weight could be anything. Even something like an equal amount of cable going off into the void. Which, depending on the cost of the stuff might be a good idea, because after you get done climbing from the surface of the moon, you can keep going and fall to the end of the counterweight. When you let go you get launched like a slingshot.

Since it's rotating around the moon, it could go into, around, or out from Earth.

If it's more ribbon, yeah, no worries. It would easily burn up. Even if it was... moon rock or something, the size of it is variable depending on how far out they put it. I can't actually say if it would be small enough to burn up in the atmosphere, but it usually has to be iron or such to avoid burnup. I'm sorry I'm too lazy to crunch all the math behind this, but I think they'd have to specifically work towards turning the counterweight into a doomsday weapon and demand one beeeiiiilliooon dollars from the U.N. (But it's good to keep an eye out for that sort of thing).

Re:There is one problem...

[Anonymous Coward]

I'm not sure if this is what the GP was referring to, but the counterweight for the elevator would necessarily have no angular momentum around earth, and it is on the earth side of L1. Therefore if the cable were severed, we would expect it to have a good chance of crashing into the earth.

Re:There is one problem...

[Anonymous Coward]

Why can't you have the upper terminus hover over a fixed position?

The moon is rotating, once per month, so why isn't it possible? I suppose because it's so slow, the "geosynchronous orbit" (lunasynchronous?) of the moon must be quite far from the moon then? But, with the moon's gravity being low, you are going slower on your orbit anyway, which will make it closer....

Maths/physics geeks - what's the "geosynchronous orbit" distance of the moon?
It would need to be lower than the "Hill Sphere" of the moon for it to be viable. (Hill Sphere would be the region where the moon's gravity dominates, and not the earth's or sun's according to wikipedia).

There's a wiki page on a lunar space elevator which talks about using the Lagrange points, but doesn't answer my maths here.

Hmm.. Just thinking here - the earth takes 28 days to go around the moon, right? (Although we usually think of it as the other way around...) Does that mean the earth is at the lunar-syncronous distance???

Re:There is one problem...

[Immerman]

Actually, anything beyond the L-points will orbit the Earth, not the Moon. As for burning up - I'm not so sure, keep in mind the that at a quarter million kilometers long the cable is long enough to wrap around the equator more than three times. It seems likely that at least some of it would make it to the ground, and even if it didn't the pollution from that much cable burning up in the atmosphere could be a major issue in it's own right.

Re:There is one problem...

[david.given]

Any severed remnant of the cable will enter an orbit based on the tangential velocity of its centre of gravity. Assuming the mass of the cable is insignificant with respect to the counterweight, then the centre of gravity will be at the upper counterweight, which is 135000km from Earth and goes round the Earth once a month, so that's a tangential velocity of... (does sums...) 330 metres per second.

Plugging the figures into the a crude orbital simulator because I can't be bothered to do the maths properly, I see that this orbit will have a periapsis of approximately 2500km, which is well within the Earth's surface. So, yes, the upper counterweight will impact the Earth.

In real life the mass of the cable won't be significant, so the centre of gravity will be much closer to the moon than the upper counterweight, so the periapsis will be higher. I see that in order to clear the Earth's surface at periapsis you'll need a tangential velocity of about 600 metres per second. (Of course, since the cable is really long, just because the centre of gravity clears the Earth's surface doesn't mean that the trailing cable will.)

As for damage? I'd reckon that any space elevator cable will be built as lightly as possible, and so will most likely instantly burn into vapour in the upper atmosphere.

Re:There is one problem...

[Immerman]

Actually, I believe they're talking about the cable itself being the bulk of the counterweight, hence the quarter million km length rather than only the 60,000 necessary to reach the L1 point. Probably for the best as the cable is far more likely to burn up than a counterweight. And the fact that it will be tumbling at a different frequency than it's obit means that even if the CoM clears the planet sooner or later one end of our cable fragment certainly will not - and more to the point the cable won't be strong enough to support having one endpoint that deep in the Earth's gravity well, so the cable will break up further casting fragments of itself into the atmosphere, eventually leaving a portion of itself in a stable tumbling orbit. Meanwhile as the fragments enter the atmosphere they will likely still be long enough that it will take quite a while for the entire thing to enter, and as drag burns up the leading end it will also be (de)accelerating the rest, so the trailing end may well be traveling slow enough to survive reentry.

Huh, you know I hadn't really thought about just how slowly the top end of the elevator would be moving, actually less than equatorial surface speeds - it would actually only take ~5% more energy to dock with the elevator than to reach geostationary orbit, and over 8000 times less than necessary to match lunar orbit (though you could admittedly use the Moon's gravity to get much of that with minimal cleverness) Perhaps such an elevator would have useful applications after all...

Re:There is one problem...

[Anonymous Coward]

But with gravity less on the moon, it would still weigh less.

er.. does the moon rotate fast enough??

[romanval]

woudln't you need a body that rotates fast enough (at the equator) to keep the elevator line taught?

Re:er.. does the moon rotate fast enough??

[Anonymous Coward]

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).

Re:er.. does the moon rotate fast enough??

[ClickOnThis]

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.

Re:er.. does the moon rotate fast enough??

[fustakrakich]

The moon does not rotate.

?? The lunar day is approximately 672 hours

Re:er.. does the moon rotate fast enough??

[randall77]

The moon does rotate, just at the same speed that it orbits (once every ~28 days).

Re:er.. does the moon rotate fast enough??

[Anonymous Coward]

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).

And the Earth is flat and the stars are but pinholes in the curtain of night, we know, we know.

Re:er.. does the moon rotate fast enough??

[Anonymous Coward]

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.

It also "wobbles", at most you can see about 59% of the moons surface, from the earths surface. So a stable anchoring directly to the moon would be harder. But you only need to anchor it on earth, because the centrifugal force would be far in excess of what is needed(lift up 10-50times the current payloads), if you stretch it to L1.

Re:er.. does the moon rotate fast enough??

[darenw]

There is no lower limit of necessary rotational speed for a space elevator to work. But the slower the body spins, the longer the elevator cable must be. For the moon at one turn per about 27 days, it's roughly 90,000 km (55,000 miles) but this isn't a great answer. The Earth's gravity is more than a small perturbation; the elevator must be designed with ideas of Lagrangian points in mind not just a simple Kepler's law. L1 and L2 are around 60,000 to 70,000 km from the Moon, and the elevator would have to extend well beyond that range with a counterweight at the end.

Earth's geostationary orbit is about 36,000 km up from Earth's center, about half the distance from the moon to L1 or L2. Only a factor of two? The Moon has much less mass than Earth, so an object in circular orbit at some given radius moves much slower as compared to the same radius orbit around Earth, but the Moon also rotates much slower, so it's closer to matching that object in orbit.

Note that the Lagrangian points are determined only by the masses of Earth and Moon, and the Moon's orbit about Earth, and have no relation to the rotation of the Earth or Moon. We are lucky to have the Moon's rotation tidally locked, otherwise a lunar space elevator might be impossible.

The wikipedia articles for "lunar space elevator" covers the details fairly well, and "space elevator" shows a little bit of math, with links to references. An online calculator at http://www.1728.org/kepler3a.htm might be worth playing with, but only for the simple Keplerian situation - a lone planet or one with small moons.

One other thing a Space Elevator needs...

[yotto]

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.

Re:One other thing a Space Elevator needs...

[alphatel]

They're forgetting the single most important part of a space elevator: It needs to actually be useful.

But we can use the ribbon to hurl the moon at Melancholia and save ourselves!

Re:One other thing a Space Elevator needs...

[Grishnakh]

We don't go there because we're shortsighted and stupid. There's plenty of things the Moon would be good for, such as astronomy, and especially mining. There's a lot of He3 there, which would be very valuable for fusion reactors.

Re:One other thing a Space Elevator needs...

[Iskender]

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.

For the Apollo missions, they needed their rockets to use fuel to lift the fuel that carried the payload that was fuel for the lunar descent to retard the fuel needed to lift the fuel for the ascent. It gets complicated pretty quickly.

Absolutely none of this was of course free, and the most expensive substances were those at the lunar end - every gram has a much larger fuel equivalent at the start of the process.

It will still be expensive to go there even with the elevator, but any reduction in price will inevitably create new applications. The obvious example being sample return: scientists want all the moon they can get, and rock from a single point on the equator will do just fine.

Re:One other thing a Space Elevator needs...

[randall77]

First we need a fusion reactor.

Re:One other thing a Space Elevator needs...

[p0p0]

No, it's more like you living in London and him in Seattle, then building a tunnel between your houses that takes half the time and cost to travel between the 2, no too mention is is easier then catching 3 connecting flights and a submarine to Atlantis before the UFO transfer and bomb drop to Seattle after which you still need to ride in a cab.

It is significantly easier and cheaper, much more than you are making it out to be.

Re:One other thing a Space Elevator needs...

[Anonymous Coward]

London? More like "he lives on the Moon!"

Re:One other thing a Space Elevator needs...

[jfengel]

If we had helium fuel, we could have helium-fueled fusion energy, if we had a fusion reactor.

Re:One other thing a Space Elevator needs...

[bware]

There's plenty of things the Moon would be good for, such as astronomy, and especially mining. There's a lot of He3 there, which would be very valuable for fusion reactors.

The moon sucks for astronomy. It's covered with a particularly nasty form of dust, the temperature variations are extreme, and your telescope is in the blazing sunlight for two weeks at a time, so your duty cycle is horrible.

What can you mine on the moon that you can't mine on Earth for much cheaper? And by "much" I mean astronomically.

How about if we actually come up with working fusion device that uses He3 before we go start mining the mythical He3 on the moon?

Re:One other thing a Space Elevator needs...

[Grishnakh]

I'm sure the dust problem can be overcome with engineering. How much worse can the temperature extremes be than what our orbital telescopes have to deal with? As for sunlight, isn't that already a problem on Earth?

For mining, it's hard to say without actually going there and looking more closely. There's tons of stuff we mine now that it very rare and we could use more of. Even copper is getting more and more rare, as the prices for it keep rising greatly, and it's of critical importance to our technology. Lithium would be nice too. Plus, our existing mining processes cause enormous environmental devastation.

He3 on the moon isn't "mythical".

The moon would also be an excellent location for low-gravity manufacturing processes.

Re:One other thing a Space Elevator needs...

[DerekLyons]

They're forgetting the single most important part of a space elevator: It needs to actually be useful.

This is Micheal Laine you're talking about here - useful is optional and definitely secondary to his Vision of a Glorious Future.
 
Did they ever get around to repossessing his 'factory' in (IIRC) New Jersey? He's come a long way from shilling for dodgy tech based initiatives, but that's long been his pattern - when one scheme falls apart, move on to another even more dubious one.

Re:One other thing a Space Elevator needs...

[Anonymous Coward]

Just paving the lunar desert with in-situ manufactured solar panels might be a better idea, at least in the short term. Should get you quite a lot of power - to manufacture more panels... :)

Re:One other thing a Space Elevator needs...

[bware]

Why deal with dust at all? Put your scope in space.

The temperature extremes are much worse on the moon - close to absolute zero to hundreds of K if my memory serves right . In space, you just put your scope at L2 or Earth-trailing, build a passive solar shield (or use a cryopump if you need really low temps), and point it away from the sun. Voila, constant temperature and 100% duty cycle. Put your scope in space.

There's also the fact that during the two weeks of duty cycle where you can operate the scope, you don't have solar power, so you have to have some way of storing energy. A telescope in space just uses solar panels and gets power 24/7. You'll have to cool your electronics half the time, and heat them the other half, so again, power, and storage. Go ahead, say nuclear. My understanding is that the moon has very few heavy elements, so all that has to come from Earth. So add a nuclear reactor, RTG, or batteries to your expenses.

Telescopes on the moon have to have pointing mechanisms, and the moon has gravity, so it's more mechanically complex (dust, vacuum). Telescopes in space have reaction wheels and thrusters to control pointing. No dust, and also few moving parts in vacuum. Much simpler. Put your telescope in space.

That is, in fact, why we are putting our telescopes out at L2 or Earth-trailing. Hubble would have been there had it not been for the mandate that it ride the shuttle. Have you noticed that we're not putting telescopes in Earth orbit anymore? It's not because we don't have the shuttle. It's because Earth orbit is sub-optimal, and not just a little bit.

As far as comparing astronomy on the moon to astronomy on Earth, well, Earth has a lot of advantages for telescopes, and that's why there are lot more of them here on Earth than there are in space. Not least that you can breath the atmosphere and find cheap places to sleep and have grad students pull the late night shifts. There are of course disadvantages, and you could never have JWST on the ground, but the moon is just not a great place for telescopes. I'm not entirely talking out of my ass here. I've sat in the rooms where these tradeoffs were made, and the moon gets put on the list. Then we start ranking. The moon ranks low in performance (duty cycle, power), high in cost (humans in space suits have to build it, everything has to be shipped from Earth), and high in risk (you have to ask why, srsly?). Then by the wonders of Excel, the moon drops to the bottom of the rankings.

But it is considered.

That's even assuming we had the capability to build a telescope on the moon. Which would be insanely expensive. Humans building telescopes, launchable or not, where they can breathe is always going to be way cheaper than building them on the moon.

Care to link to any peer-reviewed documentation that shows the abundance of He3, or any other interesting mine-able elements on the moon? I am ignorant of the geology of the moon, so if there's evidence that there are mine-able elements on the moon (including He3), I'd be happy to have my ignorance lessened.

You haven't really addressed the question of you know, actually having a working fusion reaction that needs He3. We don't. And probably won't any time soon. What are the economics of mining something we don't yet need and is difficult to store?

Re:One other thing a Space Elevator needs...

[symbolset]

A company named Planetary Resources is working on this. They're in Seattle.

Re:One other thing a Space Elevator needs...

[bware]

Holy cow. Never mind, I just read the Wikipedia page for He-3. It's even more far-fetched than I thought. 150 MT of regolith to get 1T of He3 (1.5e8:1 !!!), and He3 fusion might not even be realistic?

Sigh.

Re:One other thing a Space Elevator needs...

[multimediavt]

I think the idea is that we will have already hurled a bunch of people and equipment to the Moon (or are getting ready to do so) and we have a "cheaper" way of getting stuff back than using 1/8th the thrust to get stuff off the Moon's surface than we do the Earth's. 2020 is a bit ambitious for that goal. Be more like 2050 or beyond. Remember, in the 1950s they thought we'd have flying cars by the 1980s.

Re:One other thing a Space Elevator needs...

[FatLittleMonkey]

"Hubble would have been there had it not been for the mandate that it ride the shuttle."

Hubble was serviceable, hence it needed to be in LEO. It had nothing to do with being launched on the shuttle. Plenty of probes have been launched beyond LEO from the shuttle, they just use an upper-stage (just as they would if launched from anything else.)

Re:One other thing a Space Elevator needs...

[Anonymous Coward]

We don't go there for a very good reason: Its expensive as hell.

Hell is NOT expensive. It's free, or else it's very expensive, depending on what you're counting as your currency.

Re:One other thing a Space Elevator needs...

[jamstar7]

Why deal with dust at all? Put your scope in space.

A radio telescope? Naw, put it on Farside. It'll have a small planet between it & all that radio noise from Earth to block it, should make for some sensitive scopes. As for an optical telescope, just put a barrel around the mirrors to keep out the daytime sun. The big problem is going to be thermal expansion of the optics. It'll seriously warp 'em.

Re:One other thing a Space Elevator needs...

[Immerman]

Indeed, the far side of the moon would likely be excellent for radio telescopes - great noise shielding, no optics to worry about with that hideous, clingy, jagged dust, and thermal warpage can probably be dealt with fairly easily. Don't see any advantages for optical scopes though, other than maintenance is easier than in space - assuming of course you're already there for other reasons.

Re:One other thing a Space Elevator needs...

[Anonymous Coward]

I'm still waiting for the ham sandwiches.

Re:One other thing a Space Elevator needs...

[Anonymous Coward]

One day you're going to realize your world-view is essentially fantasy and fiction. I don't want to be around when that mental breakdown occurs.

Re:One other thing a Space Elevator needs...

[Grishnakh]

Yes, I'm sure some dimwit like you said the same thing to people like Christopher Columbus and the other new world explorers.

Re:One other thing a Space Elevator needs...

[bware]

I honestly don't know the design process (before my time), but my suspicion based on vague conversations with people who were around back then, is that Hubble was designed to be serviceable because it is in a shuttle orbit, i.e., the mandate to be on the shuttle drove these design decisions, not the other way round. But I could be wrong.

I know that on the designs I've partipated in, we didn't like LEO because of the bad duty cycle (90 minute orbits, temperature variations), and even back when we had the option of launching on the shuttle, we'd prefer to use something else and be somewhere else. L2 and earth trailing orbits are superior for observations, and the shuttle was just about the most expensive way to get things into orbit - other launch systems are significantly cheaper. And other launch vehicles are more reliable.

ISS is not a great science platform for the same reasons, plus vibration and very limited power.

Re:One other thing a Space Elevator needs...

[bware]

As for an optical telescope, just put a barrel around the mirrors to keep out the daytime sun.

Then why don't we do that here on Earth? Most telescopes here only operate at night. You've noticed the domes with the sliding roofs, right? I submit that any telescope sensitive enough to be interesting would get absolutely killed by sunlight and scattered light.

Re:One other thing a Space Elevator needs...

[catprog]

For mining, it's hard to say without actually going there and looking more closely. There's tons of stuff we mine now that it very rare and we could use more of. Even copper is getting more and more rare, as the prices for it keep rising greatly, and it's of critical importance to our technology. Lithium would be nice too. Plus, our existing mining processes cause enormous environmental devastation.

All of that stuff is cheap compared with launching stuff into space. If you can get stuff into space cheaper from the moon then earth then their is a big market. Maybe even for space based solar.

Re:One other thing a Space Elevator needs...

[FatLittleMonkey]

I honestly don't know the design process (before my time), but my suspicion based on vague conversations with people who were around back then, is that Hubble was designed to be serviceable because it is in a shuttle orbit, i.e., the mandate to be on the shuttle drove these design decisions, not the other way round.

From what I recall of that era, Hubble was always human serviceable. However, when the shuttle development was delayed, it was going to be launched on an expendable launcher, but when it was delayed, it was mandated to switch back to the shuttle. Which caused more delays to rework the telescope to make it compatible with the shuttle. Then when they were ready in 1986, Challenger happened, suspending the shuttle program for two years, and then lowering the flight-rate when they returned to service.

But people have been pushing for an large optical space telescope decades before Hubble. Hubble's core concept (a human serviceable large mirror LEO telescope, called LST, I think) dates from the late '60s, early '70s. (Indeed, the original LST was meant to launch in 1979.) So there were probably various proposals during the '70s, some wanting human-serviceable, some wanting throw-away (Called LOT?). During that debate, obviously the guys wanting human-serviceable 'scopes recruited the shuttle proponents to their side. That debate, and the inevitable acrimony, is probably what some people remember, but the shuttle-team never forced human-serviceability onto Hubble. Hubble just was the human-serviceable proposal, which won funding thanks to the shuttle. (I suspect that they only got funding from Congress for any large mirror space telescope because it involved the shuttle. The entire program was cancelled at least once in the mid-'70s. Without the shuttle connection, they would have been limited to OAO-scale 'scopes for at least another decade.)

The same factions still existed during the follow-up proposals to Hubble. The human-serviceable side had ideas for expanding Hubble with a new (external) primary mirror. Essentially turning the whole of Hubble into a secondary. The non-serviceable side obviously proposed what became James Webb, and used the cost-overruns and delays of Hubble, and the approaching end of the shuttle program, to win. (Finally they'd show those HSF idiots how to do a cost-effective and well-run program... Heh heh heh... sigh...)

I know that on the designs I've partipated in, we didn't like LEO

But if you look at the observatories that preceded Hubble, during the '60s, '70s and even '80s, they were almost all LEO. It was only in the '90s that we started to see them use the ESL-points and solar orbits. Hubble wasn't unusual for the era. And I believe all rival proposals were LEO anyway. I think Ulysses was the first BEO observatory, other than planetary probes. (Ironically, Ulysses was launched on the Shuttle.)

even back when we had the option of launching on the shuttle, we'd prefer to use something else and be somewhere else.

Different era. You knew the shuttle as a fat useless pig. Hubble was proposed in the '70s when it was sexy and new.

ISS is not a great science platform for the same reasons, plus vibration and very limited power.

(Limited power? It always surprises me to hear that, given the ridiculous size of those arrays. Have they really budgeted so little for science missions? Dicks.)

I don't think it would be too difficult to isolate an observatory module from the main station's vibrations. I think the bigger issue is the amount of cruft that co-orbits with the ISS, and pointing being even more restricted than Hubble. That said, it did surprise me that they didn't build a small crew-tended observatory module (a la the Cupola.) It doesn't have to be huge and expensive, just somewhere to test novel instruments without waiting for a whole new flagship observatory.

Re:One other thing a Space Elevator needs...

[bware]

I defer to your obviously superior knowledge of the history of space telescopes. Good information.

(Limited power? It always surprises me to hear that, given the ridiculous size of those arrays. Have they really budgeted so little for science missions? Dicks.)

Yeah, that stunned me too.

I don't think it would be too difficult to isolate an observatory module from the main station's vibrations.

It is though. Again, surprising. For reasons I would not have thought of, though after it had been explained, I guess it makes a certain kind of sense.

Further deponent saith not.

..ok, how?

[kheldan]

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.

Re:..ok, how?

[Grishnakh]

Seems like the biggest challenge would be building the cable and satellite; the work you have to do on the Moon should be minimal, mainly just anchoring the cable after it's dropped from the satellite. Of course, afterwards you'd want to build a base or something, but just to get the elevator working that isn't strictly necessary. The cable would be built on Earth. After this is all done and in place and a base is established, and mining operations started up, then we can start building up infrastructure and manufacturing operations there.

Re:..ok, how?

[Svippy]

Simple! They build the elevator on Earth, then strap it to a rocket that they fly directly into the moon. Fortunately, they have turned the elevator upside down, so when the rocket crashes into the moon, the elevator stands upward.

This is kinda like how they build skyscrapers: Build it lying down, then straight it up when it's done. Much cheaper and safer.

Re:..ok, how?

[tool462]

You're reading this wrong. 8 years is exactly the right amount of time.
It's less than 10 years, which is sufficient to attract VC funding
But it's also greater than 5 years, which is long enough to avoid any expectation of progress or success.

Re:..ok, how?

[kheldan]

See, this is in part what I'm alluding to: This really sounds as much like a way to attract investors (to potentially rip off) as it is a serious project. In this fucked-up day and age we're living in, I expect (and often see) more and more scams going on. Why should this be any different? They promise (literally) the Moon and the stars, then they have "problems" somewhere along the line, and none of it happens. Oh well! Thanks for playing. Don't look too close at our books, though, k? Thanks! :p

no way

[Anonymous Coward]

no. fucking. way

Then what?

[Anonymous Coward]

We'll still need to use old fashioned rockets to get stuff to the moon before we can launch it–again–from the moon!

Seems backwards to me. If the big hurdle getting out of Earth's gravity well, then once something is in space, the marginal energy needed to go to, say, Mars, is relatively small isn't it? Compared to going to the Moon first, then to Mars?

And do we really need unobtanium for an Earth-based elevator? Aren't carbon nanotubes theoretically up to the task? We just need to perfect industrial scale production of nanotubes.

Re:Then what?

[rickb928]

License it from Oakley, and you can try it out.

Doesn;t seem suitable, but it has so many different properties and uses in eyeglasses, who knows? Might work.

Lunar Musaz

[Grayhand]

I can just see the cable breaking and some fool tries the stunt of jumping just before it hits. Given the gravity I wonder just how much force his head would have when it hit the ceiling? A study of that could be worthy of an ignoble award.

LIftport,, Can You Hear Me Major Tom

[dontgetshocked]

Can you hear me Major Tom,,, Here I am drifting in a tin can.

moon-stationary orbit, correct me if I'm wrong

[Arthur B.]

google: ( ( lunar cycle / 2*pi)^2 * mass of the moon * gravitational constant )^(1/3)
That's 429,000km .. 1.12x the earth moon distance. Uhhh

Re:moon-stationary orbit, correct me if I'm wrong

[Anonymous Coward]

If the moon were alone in space, yes, that's correct. But we've got another big planet right next door, so you can use it's gravity to provide the additional pull on the station. You only need to get a little ways past the L1 point.

The Moon is Blue

[fm6]

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.

Re:The Moon is Blue

[Anonymous Coward]

It's Space Nuttery. The kind of physics and engineering and materials breakthroughs you'd need to even contemplate a lunar space elevator mean that you wouldn't need a space elevator anymore. This isn't a "space project" anymore than the "synthetic fuels" project of the Marriotts was about fuel, there's probably some insane and clueless Mr Moneybags throwing money at these people with a trebuchet. Like the 1997 Japanese Space Hotel, or the Solaren orbital solar power plant. Still waiting on those...

It's just modern day fairy tales.

Who is going to use this?

[Anonymous Coward]

So, who is going to use the? You need to get ppl from earth to moon first, and while doing that, why land on the moon first? The moon squirrels will send off scout recons to titan?

How about a Mass Driver?

[Anonymous Coward]

A mass driver in addition to (or instead of) this on the moon would be easier to build and more beneficial. We can get stuff to and from the moon just fine. It's getting further than the moon that's a big problem.

Re:How about a Mass Driver?

[Anonymous Coward]

Considering that the "stuff" we got to the Moon and the "stuff" we got past the Moon are pretty much the same size, I don't really see what you mean. But a mass driver is equally as delusional and completely unfeasible as this space elevator malarkey, maybe that's what you meant?

Good luck

[moniker127]

"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.

Re:Good luck

[chriso11]

I think it makes more sense to make a space elevator from LOE. All the advantages of a lunar elevator, but actually in a useful location,

Somehow relevant...

[twotacocombo]

Reservationist: Oh, I can reserve you a flight coming back from Chicago at 5:55. Does that help? Richard: Hi, I'm Earth. Have we met? Reservationist: I don't think so.

Business Plan

[Anonymous Coward]

Step 1: Build space elevator on the moon.

Step 2: ??

Step 3: ???

Step 4: ????

Step 5: PROFIT!!!

Alternative architecture

[Anonymous Coward]

Instead of a 'static' ribon or cable with cars climbing up and down, instead make the ribbon itself movable.

The payload will be attached to one end of the ribbon, and then the *entire* ribbon will be lowered until the end is near the ground and the payload can be swapped with the next upbound payload.

As the ribbon moves up, the other end can either be played out further into a higher orbit to help balance the forces, or it could be wound onto a reel. (The first is probably better, energetically speaking).

I think this idea has good potential.

Space elevator to the moon

[Anonymous Coward]

Use bricks and mortar.
How could you attach anything to an object that revolves around us/

Kickstarter campaign!

[Esteanil]

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

geostationary ?

[p51d007]

Unless the moon & earth are in a geostationary orbit, won't this think drift around? I guess having it "anchor" in space will negate that problem?

hmmm

[stevenfuzz]

So, wouldn't the elevator tether keep circling around until the moon was yanked directly into the earth? Excuse me for ignoring physics and stupid things like that.

Waste

[Anonymous Coward]

How about using that elevator to dispose of toxic waste in space.

Re:Waste

[jamstar7]

How about using that elevator to dispose of toxic waste in space.

Sounds good. Let's start with Congress...

they forgot to do somet math apparently

[slashmydots]

So let's see, how fast does a spaceship go after blasting off with a rocket? And how long does it take to get to the moon? Okay, now let's compare that to the speed of something traveling along an elevator wire. If it's pulled by the wire, the most powerful metal alloys in the world still wouldn't hold up to a reasonable speed. Then there's friction so let's say it's mag-lev, except not really lev since it's going straight up. That'd get maybe 100MPH if they're lucky since a bullet train can go like 200 on the ground going perpendicular to gravity. So I hope they enjoy their 6 month long journey to the moon on that elevator.

Time to invest in McNeil Laboratories.

[Anonymous Coward]

Makers of Haloperidol, a long-acting and safe anti-psychotic. Only a howling, sweating, shivering and delusional lunatic would think that a space elevator on the Moon would be even remotely feasible in 2020, let alone ever.

It's a winner!

[mark_elf]

I can see how bitcoins fit into this, I can see how kickstarter fits in too. Nibiru, obviously. Raspberry Pi... I need more to work with here.

Simple.

[Anonymous Coward]

Just build the elevator here on Earth where we have all our industrial resources, then just use the usual sci-fi hand-waving to swap the Earth and the Moon's positions while keeping the elevator stationary. Ta dah! Easy peasy. This will finally open up the critical vacuum markets that will really send the private corporations scrambling to be the first. I mean, think about it, RCA and Sylvania will be able to rise up, Phoenix-like, from the ashes of the dead dreams of the Space Age to open up vacuum tube factories on the Moon. Savings in the vacuum pumps alone will make the space elevator a done deal!

People have stopped laughing...

[Anonymous Coward]

because they're fed up with fed up with the endless series of websites with pretty pictures, created by people who obviously don't know what they're talking about.

maglev?

[aztec1430]

Wouldn't it be easier to build a maglev accellerator?

Kevlar is strong enough for the job....

[Anonymous Coward]

'Rockhound: You know we're sitting on four million pounds of fuel, one nuclear weapon and a thing that has 270,000 moving parts built by the lowest bidder. Makes you feel good, doesn't it? '

Um no.

Here's your peer reviewed documentation

[Anonymous Coward]

www.imdb.com/title/tt1034314/

Undeniable proof that there is plenty of mineable He3 on the moon... and that the nazi's got there first

The solution is clearn...

[Anonymous Coward]

A DYSON SPHERE!!!!!!!!!!!

Sure they will.

[Anonymous Coward]

Yet another entity claiming they are planning to do something by an unreachable date.

If it happens by 2020, I'll donate $3000 (Three Thousand Dollars) to charity

mass accelerators

[micahraleigh]

Would a mass accelerator be a much cheaper alternative to an elevator? (On the moon or earth)

Moon Elevator: Does it levitate?

[Bite_MSMA]

I call bullshit on this one. "Unobtainium"? Give me a break!

Re:Moon Elevator: Does it levitate?

[stillnotelf]

http://lmgtfy.com/?q=unobtainium

This is a great idea...

[ToddInSF]

First, bridges to nowhere; now, elevators to nowhere !

spectacular failures

[ethanms]

Whenever I hear about these things all I can think of is the inevitable spectacular failures that will occur when something snaps that ribbon and 50-100 miles of ribbon start pouring out of the sky...

On the moon I guess you'd wind up with a massive pile (like that scene near the end of Twins when Schwarzenegger and Devito drop the chain on the bad guy)...

On earth, with wind, rotation, etc... you might have a massive ribbon falling over span of 10's of miles, landing on homes, schools, highways, people...