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Thoughts on the Space Elevator
Keith Curtis writes to tell us that Glenn Reynolds, of Instapundit fame, has posted his thoughts on why NASA should be building a space elevator instead or their current plans. Keith has also posted his throughts from an engineer's perspective (although admittadly still not a rocket scientist). "The challenges are many, but it has been a viable option since carbon nanotubes, structures so strong that one the width of a human hair could lift a car, were invented. A space elevator could be between 10 and 2000 times cheaper than conventional technology and will force NASA to change just about everything they do. Hopefully one day that bureaucracy will wake up and realize it."
Yeah but who wants to listen to that god awful music?
If magic pixie dust were invented it would be such a waste to spend all this money on conventional boosters. Come on NASA! Drop what's known to work and concentrate on the pixie dust formula.
But, I don't remember ever hearing that we actually have the technology to produce enough carbon nanotube material to actually build a prototype device of some sort let alone a cable spanning to LEO. I realize it's 14 years away.. but there's no guarentee we will actually have the capacity by that time. As far as I'm concerned we're better off building what can actually be finished come 2020 let alone tested and on our way to the moon.. again..
I wonder how long it will take for one of these elevators to reach their destination. If the elevators are going to take a long time they need to be big enough to hold some food and other supplies. I'm sure they will be big enough to send up large equipment though...
Sigh. Ya know, we could build a structure to space with todays (hell, 20+ year old) technology if we wanted. The Launch Loop concept was published 20 years ago and is viable today. It costs less than a space elevator is predicted to cost and, unlike the space elevator, can be built from the ground up instead of from orbit down. So yeah, please stop saying stuff like: once we have strong carbon nanotube fibres we'll have a space elevator two weeks later. It doesn't work like that. The majority of studies that remain to be done to make the Launch Loop a reality are much the same as the many studies that still need to be done to make the space elevator a reality. Someone has got to finance those studies and unless you can get PhD students to do it on government funding that means you've got to pour money into a hole that might never fill up.
How we know is more important than what we know.
this is where private ventures come in. let them take the risks and develope the tech. i'm dubious about space evelvators, but hell it's at least possible in theory if you can find materials that will last
If you mod me down, I will become more powerful than you can imagine....
A space elevator will be made of carbon fiber nanotubes correct?? What would be the effect on a hurricane hitting the elevator? Can the string be realed in from one end?? Would it be more prudent to build this in a place far away from a coastline??
Gorkman
Why isn't this stuff being used as an emergency rescue material, to make ladders that can be telescoped up to the 30th floor of skyscrapers? Surely there could be less ambitious projects for this material before committing to something that has to deal with the extreme stresses and temperatures in space and the upper atmosphere?
Make a model of a space ladder/elevator, by designing something that can save lives here at home, and it will take off like a rocket in the public's eye, pardon the pun.
Saskboy's blog is good. 9 out of 10 dentists agree.
I like the idea of the space elevator . . . but won't it be a prime target for terrorist attacks? I mean, if I was a terrorist, it'd be the first place I'd direct my hijacked pla . . . moment, there's a knock at my door.
The August issue of IEEE Spectrum also had a story about the space elevator. This article is available online here. Not knowing much about the space elevator, I found this article very informative.
It's going to be one hell of a long ride and I'd hate to overdose on strings.
Abstinence is a government conspiracy. www.SafeSexZone.co
If construction was anything like programming, an incorrectly fitted lock would bring down the entire building...
First of all, the ribbon idea won't work, it will get curled up since it will stretch unevenly and wind and dirt will do the rest. The only practical shape for a rope is a round one. Secondly, building a climber with motors and lasers and crap is totally ridiculous, unbalanced and inefficient. Put a friggen pully at the counterweight, with solar panels and an electric motor and another damn pully at the bottom with another motor, then run two cars up and down. Then the system is balanced. Yes, the two cars will probably bang against each other when passing - so slow down when halfway and shape them to handle it so they won't get stuck even if the ropes are twisted. KISS.
Oh well, what the hell...
I know we have to plan for the future and all, but since Mars travel probably won't be viable or even valuable for another 60 to 80 years (by which time I'll probably be dead) I would much rather have a nice reduction in taxes.
... but I really think the people should be allowed to choose which optional programs get their money - if it really needs to be taken from them in the first place.
How about this - reduce our taxes a bit, and for the non-critical portion of our taxes let us choose what program they go toward funding. Some people might choose a government funded AIDS cure - some might choose Mars exploration
Maybe i am a bit out of touch (although i doubt it, being physicist and seeing people who actively work in the nanoparticle research and astrophysics department everyday), but i think this is all such a bullshit.
Space elevator this, space elevator that. Its just a pie-in-the-sky dream, and will be for the next century(ies). We dont have bucktubes "thick as a hair but strong enough to lift a car".
We dont even have them a meter long and strong enough to lift an apple.
And even than, it took millenia to get from iron->steel->a few km steel wire for bridges/ect.
Singularity this or that, you shouldnt expect something like the support of the golden gate bridge via nanotube based cables the next decade(s)
(not even mentioning the hurdles of a structure 30.000km+ long and sturdy enough to support the lifting vehicle and atmospheric conditions).
Also, the best we ever did concerning long wires and space was a test a few years ago, where they even failed to unwind a 300km, unstained wire in free space.
Not to mention that to get the whole framework running you need an efficent way of getting material and people up there to begin with... without a shuttle mk2 or 3 or 4 or 5 there is not even a point to start the whole shit.
But it seems nowaydays you only need to throw some buzzwords like "nanotubes" into the crowed and they would believe you even if you promised them portable teleporters...
HI O WISE PRINCE. WHT TOOK U SO DAM LONG?
That's even better, because this is an engineering project, not rocketry.
The first thing that I thought of when I first heard about this is what a great terrorist target it would make. You could shoot at it for many miles around, which might not affect it much if it's as strong as it sounds like the material is, but one would be able to see when it was in use. It's unrealistic to think that people around the world would constantly be taking impudent potshots at anything with any accuracy, but still, it remains a very visible target, and one that would be very difficult to replace.
On a different note, I see that this would be a social and cultural catalyst. What if we build this elevator in the US, and China wants to use it? It would seem wasteful to demand that China build their own space elevator to do exactly the same. Either we would allow other nations to use the elevator as well, thereby showing at least superficial unity, or we say that we have the world's only space elevator, and if China wants one, they must build their own, which would almost certainly dampen relations.
I won't speculate on what will happen, but I think either eventual harmony or inevitable conflict would be accelerated by something of this magnitude.
No, it hasn't.
The space elevator will become viable when someone creates a strand of carbon nanotube and lifts a car with it.
If you want to make me believe that a carbon nanotube space elevator is a viable proposition, demostrate that you can build a carbon nanotube suspension bridge first.
Doesn't have to be a replacement for the Brooklyn Bridge or the Golden Gate. A footpath over a creek at your local engineering college will do.
Until then, you're as likely to go into orbit on a space elevator's as you are on a matter/antimatter drive: as in "not at all".
The LiftPort Group of companies working towards a space-elevator are making a great deal of progress. Slashdot reported on the faa approval of their high altitude tests, for example. See here and here for more LiftPort specific information. Check here and here here for several reports concerning the viability of the elevator -- be sure to check the NIAC pdf. Blaise Gassend has a great collection of information. Finally, though carbon nanotubes are still in their infancy (its been a little around ten years since they were discovered) - their theoretical tensile strengths are perfect for application in a space elevator construction. This recent development spells a rosy future, and many innovations yet to come.
All this is mute until we can make nano tubes as easily and reliable as we make rope.
So no-one is able to speak aloud about it?
Ooooooh, you mean moot!
</pedant>
C17H21NO4
...one giant leap for the first wise ass to press all the buttons (Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere...) and piss off the other astronauts.
--I'm so big, my sig has its own sig.
-- See?
I don't think that's the right way to think of it. Call it stepping stones. There's no point in abandoning short term projects for a long term one. There's no point in completely abandoning known working tech for something that's totally theoretical.
It's probably a lot cheaper to "revamp the Apollo capsule" than it is to insist on such a great leap in tech, that tech being more of a curiosity at the moment than anything else. Taking things too radically different is what got us the Space Shuttle, when Soyuz+Mir and Soyuz+ISS has been doing far better, being older tech yet.
So far, despite the significant amount of research, I don't think the nanotubes have been made in kilometers, never mind 33000 kilometers or whatever it is necessary, and there are a lot of logistical issues.
Launch Loop presentation and Space Elevator presentation .
For large projects to be realized, they either have to be of decisive strategic/military value during war (Manhattan project), or they have to completely capture the hearts of the citizens that are supposed to pay for it all (Apollo Project, "before this decade is out..."). Clearly, for the Space Elevator, the latter is the case. I, for one, have not heard of Launch Loop before, and the dry PDFs and text files that are Google's #1 on the term didn't really invite me to care about it. The Space Elevator, on the other hand, has been part of the popular culture for decades, and has recently surged astronomically (no pun intended) in terms of mainstream recognition.
Just as it would have been more affordable and scientifically more valuable to gradually conquer space and ultimately the moon (i.e. with manned space stations and a launch from space etc.), it was the extreme appeal of the "moon shot", the giant leap that won the favor over the more economical approach.
The grass is always greener on the other side of the light cone.
Structural engineering issues aside, the big problem with space elevators is the junk in low earth orbit. If a 200 kg object hits the structure at a relative velocity of 15,000 MPH, it will release energy equivalent to one ton of TNT.
...is that rockets/space shuttles garner much better publicity. Until they blow up, at least.
NASA's Exploration Systems Mission Directorate is already funding space elevator research - John Mankins who was formerly a big cheese at ESMD is a space elevator advocate. One of NASA's Centennial Challenges is to directly foster space elevator work. A Space Elevator is at the moment an idea. Building a space elevator with current technology and expertise may be even less practical than sending humans to Mars with current technology and expertise - much further work is needed but for space elevators the unanswered questions are arguably more fundamental. People love to criticize NASA and point out how company X, Y or Z already has capability A without considering that there are fundamental reasons e.g. to do with energy, systems scaling etc which mean that going to Mars is vastly more difficult than say a suborbital hop. Companies working on prototype space systems and tackling problems in innovative ways should be encouraged by they do not yet provide a certain path towards desired goals like putting people back on the Moon.
Prolog rules
If you simply want to get cheap payload into orbit this decade using materials that are NOT theoretical, find a way to get funding to the blimp-to-orbit people at JP Aerospace.
Lots of things wrong with the Space Elevator concept... it breaking could kill a lot of people... but the dealkiller is that you can't build a structure with theoretical materials, and it shouldn't take a "rocket scientist" to figure this out.
Tech Public Policy stuff
Can be... could be... That's the problem. The tech isn't there. The carbon nanotubes that are long enough, aren't strong enough. The carbon nanotubes that are strong enough aren't nearly long enough.
The tech isn't there. How can they start building something that doesn't have the prerequisite materials? The current plan NASA is proposing they can start building **soon**.
The R&D you need to produce space elevators is currently being performed worldwide by a variety of companies and is well-funded. Diverting $100B isn't going to up the timescale **that** much. Not to mention while it looks good on paper, we haven't even tried a prototype yet.
-everphilski-
The force in a rope is always tension and always the same everywhere along its length (assuming zero mass). You can't push a rope.
Therefore, a system with two cars and pulleys will always be almost in balance. The actual force in the rope will change depending on where exactly the cars are, due to centripetal forces.
The 'almost' is due to taking up more stuff than you are bringing down, or the other way round if you are mining a solid naquata asteroid, or due to a load of gold plated latinum as payment from the Firengi...
By keeping the system in near balance, the energy required is much reduced and you don't need any friggen sharks with lasers on their heads to power the system.
Oh well, what the hell...
When the light begins to change
I sometimes feel a little strange
A little anxious when it's dark
I have a constant fear that someone's always near
I have a phobia that someone's allways there
Sometimes when you're scared to take a look
At the corner of the room
You've sensed that something's watching you
Have you ever been alone at night
Thought you heard footsteps behind
And turned around and no one's there?
Because you're sure there's someone there
Watching horror films the night before
Debating witches and folklore
The unkown troubles on your mind
Maybe your mind is playing tricks
I have a constant fear that someones always near
Fear of the dark, fear of the dark
I have a phobia that someone's allways there
When I'm walking a dark road
I am a man who walkes alone
Sometimes I think Merkins would be happier if they listened to their own Rock'n'Roll and thought about it...
The elevator has to climb the rope/ribbon. Even at 100km/hr that's 200hrs to geostationary orbit. Too slow to make passing through the Van Allen radiation belts survivable by humans.
Dodging freak weather is an issue which requires a mobile base station to manoevre the base of the cable. Similar mechanism is required to dodge space junk and meteorites.
Oscillations in the cable must be damped.
Cost per kg lifted is cheap ONLY if the initial capital cost is ignored.
This is just a few of the many gotchas. But this romantic pipe dream has grabbed the imagination of many who are prepared to (i) understate the problems and (ii) understate the cost. See http://en.wikipedia.org/wiki/Space_elevator
Paul Beardsell
Its just a pie-in-the-sky dream, and will be for the next century(ies). We dont have bucktubes "thick as a hair but strong enough to lift a car". We dont even have them a meter long and strong enough to lift an apple.
Exactly. Wake me up when we have a carbon nanotube bundle as thick as my arm, and as long as my car. Then tell me how much it will cost to manufacture.
Then build a bridge or two out of it, to prove that it's as strong as the theoreticians think.
For comparison, the world's longest suspension bridge is Akashi Kaikyo Bridge in Japan. It has a main span of 1,991 meters, or under 2 km. It cost an estimated 500 billion Japanese yen (U.S. $3.6 billion) to build the bridge. It took ten years to build.
That's for a problem with well understood materials science, done under normal Earth gravity, with normal, terrestrial manufacturing and construction processes.
With the space elevator, people can't even agree on how big it has to be (either 100km, or 36,000 km, or somewhere in between), how strong it has to be, or where it will be built.
In any case, right now it's 50 times longer, and billions of dollars more expensive than the billion dollar bridge: and that's just the material's cost. We can't build a space elevator yet. Why?
If we don't have agreement on a design yet, and we don't have a materials supplier, and we don't have a budget, and we don't have a prototype, and we don't have a plan... how the heck is anyone supposed to build it?
Any decent engineer would throw those plans back on his client's desk, and tell them to come back when they had worked out exactly it was they wanted him to build.
A space elevator isn't going to be built until we have cheap, reliable, and available materials build it out of, until we have machines capable of building it, until we have trained construction technicians capable of operating those machines, and until we, in general, know and agree on what we're building, what we're building it out of, how we're going to build it, what it's going to cost, who pays for it, and who bears the liability for failure.
That day may come. But there's one heck of a lot of materials science that needs to be done first. Build a large carbon nanotube cable. Then build a cheap one. Then prove that you can build a few hundred thousand cables in a cost effective, time efficient process. Then prove that the cables remain strong and reliable under all adverse conditions. Then find a way to mass produce them cheaply and safely, without health hazards to the workers who build them. I doubt that will take less than ten years, probably more like thirty, before we've got the fundamental materials science for carbon nanotubes down.
Once we've done all that, we'll finally have enough data to decide if we can really build a "space elevator", and how much it will cost, and whether the costs will be worth it.
Wake me up in thirty years.
--
AC
Because angular velocity and rotational velocity are not the same thing.
The only place where the rotational velocity of a Stalk matches the Earth's (466 m/s) is at the equator where it's tethered. At GEO it's going 3,070 m/s.
Hurricanes are not so much of a problem. They might tear some of the structures off the sides of the Stalk, but given the cross-section of a Stalk in the face of winds it would encounter and its tensile strength and total mass, the worst a hurricane could do is put a slight oscillation in it, something that stationkeeping thrusters could easily deal with.
Even if you somehow managed to sever it at ground level or even a few miles up, only the part below the break would wiplash.
To get a significant planetary wiplash it would have to be severed several hundred or thousand miles up (i.e. in space). Then you're talking about terrorist nukes or a cometary or asteroidal impact. If something made a Stalk wiplash, my money'd be on the terrorist nuke.
I think we need billions of dollars of investment in upgrading our antimatter production facilities. The space elevator only gets you into orbit, antimatter can get you to nearby stars.
From TFA: It would cost about $6 billion in today's dollars just to complete the structure itself, according to my study
From the parent: I've heard a similar figure before, and it's amazingly cheap if you think about it.
From me: It's only cheap because it's the amount is at best misguided, or at worst an outright lie.
The worlds longest bridge was just completed in Japan: it cost 3 billion US dollars to build, and took ten years to construct.
The bridge was only 2km long. The smallest distance anyone says we need to reach space is a full 100 km; some people say we need 36,000 km instead.
If we could build a space elevator out of steel (we can't!), and if price scaled linearly with length (it doesn't!), and if we weren't building straight up (we are!), it would still cost around 50 * 3 billion or $150 billion dollars to build.
If the construction time scaled linearly (it won't; we've never built a space elevator before) it would take 50* 10 = 500 years to complete.
That's the time and cost to build a bridge as long as the shortest elevator, without any special R&D costs. That's well more than the $6 billion the article claims, or the $100 billion he says NASA is "wasting" elsewhere.
The article also claims that carbon nanotubes have been manufactured which a lift a car; this just isn't true. He's lying to make things sound good; carbon nanotubes may have that strength in theory, but no carbon nanotube has ever lifted a car.
Carbon nanotubes are currently an interesting research project, not a building material! I can't get carbon nanotubes at my hardware store; they currently only exist in labs, are too tiny to see, let alone build with, and cost more per unit volume than gold! The longest carbon nanotube manufactured to date was only 4 cm! Attempts to stitch carbon nanotubes together have currently ended up with fibres weaker than kevlar; far too weak for a space elevator.
We can't build a space elevator until we first get building materials that are big enough to actually see, let alone construct a 100 km chain out of. We'll also need a minimum of $150 billion dollars, probably much, much more. I'd say multiply the costs by 10 for using a brand new material (nanotubes, assuming can get them working at all ), by 10 for the human costs of untrained manpower, by 10 again for the uncertainty factor of a project that's never been done, and by 100 for working against gravity.
That's 150 trillion dollars; and I think that's a reasonably conservative estimate, all told. If we need the 36,000km version that some experts claim we need, instead of the 100 km that some people say we can get away with, the project just won't happen. Even 150 trillion is a lot; really. We could do a lot of other things with that money...
--
AC
The Wikipedia article says otherwise... it says that 65 GPa - 120 GPa are the expected required strengths. And it says that 63 GPa nanotubes have been created, and 120 GPa are theoretically possible.
It certainly sounds to me as if it's well within the realm of possibility, and that's with no fundamentally new discoveries. The foolish assumption would be that 10 years of research and $100 billion would turn up nothing fundamentally new.
The US could do with some possession by the spirit of Thomas Edison. He saw things we needed, that were obtainable with years of work from the current technology, and he busted his ass to make them happen. It could be done again. Not everything has to be laid out with every piece pre-discovered before we set out to build something. Where would we be if he had said, "Well, hair doesn't work, and copper wire doesn't work. I guess you can't build a light bulb."?
think sept. 11
Bullshit, 9/11 happened because it was a one off, it's unlikely to happen again because who is going to believe highjackers who tell you that you'll be all right if you cooperate and don't resist. That's not likely to happen again. Also you can set up a no-fly zone for 100 miles or so around the elevator and enforce it with a couple of Patriot missile batteries for distance work and Vulcan cannons for close in work. We have bunches and bunches of people in all four services thinking about ways of improving "if it flies, it dies" technology and they'd love a chance to try out their stuff.
cheap labor conservatives - they want to keep you hungry enough to be thankful for minimum wage.
Being an SE enthusiast and having presented at two of the SE conferences, perhaps I can provide some useful background.
The single greatest challenge to building an SE remains that of producing suitable material for its main structural element - the cable.
A practical Space Elevator requires a material of ultimate strength of at least 50 GPa. Individual nanotubes have been made with several times this strength, but no bulk material has approached it yet. Pure single walled carbon nanotube fibres of length 4mm or greater should produce a spun yarn with strength in excess of 100 GPa and such nanotubes have been produced in 40mm lengths, but not in useful quantities. Steel reaches 5 GPa, but has 4 or 5 times the density of CNTs and so only has a fortieth of the specific strength needed. Aramid fibres such as spectra, dyneema and kevlar come closer, but are only useful for lunar or martian SEs, not earth ones.
Almost all other issues, such as terrorism / securing the base station / wind / lightning / discharging the ionosphere / lunar and solar tidal effects / atomic oxygen erosion / radiation damage / collisions with the ISS / swarf infall / cyclic heating and cooling / broken ribbon fragments landing on people or damaging the environment etc. either turn out to be insignificant or are fairly easily solved with a little thought and effort.
The two problems that are harder to solve are: micrometeoroid impact and what has been called 'fratricide' -- where fragments from one SE failing hit other SEs. The likely solution to the micrometeoroid (mm) problem is to make the size and shape of the SE ribbon such that mms do not degrade its strength significantly during the lifetime of the SE. Fratricide is very hard to deal with and will require that ribbons be designed to be VERY unlikely to fail and that they incorporate ways to affect the paths of fragments.
Beyond these problems there remain numerous areas of investigation such as the fundamental 'mode' or shape of SE to use -- a single straight cable, or a loop, or a straight cable with pieces that are cut from the upper end. Will a material be available that will allow loops or constant-thickness cables (requires 96GPa strength) or must we use a tapered cable? How to design and, crucially, power and cool the climbers -- or will they be 'clingers' on a moving ribbon? But all of these things are engineering design choices, not impediments.
NASA has been active in funding and encouraging SE research, including several studies by NIAC (by Brad Edwards and Jerome Pearson in particular) and in promoting the Centennial Prizes for tether technologies.
Given the uncertainty in producing a suitable material, and despite my enthusiasm for SEs I believe that NASA should not yet commit any large budget to the SE, but continue its excellent efforts in promoting the idea through smaller means. It could, however, usefully commit additional funds to CNT research since any progress in high specific strength materials would benefit it even if this research does not result in material strengths useful for an SE.
and no this isn't a troll actually visualize part of a frickin space elevator falling into the ocean, or worse on a nearby town.
Only the cables below the break will fall down. The rest of the elevator will fall up.
Actually, the design for one of the ribbons was so thin and wide that the wind resistance alone meant that it fell at about the speed of a cardboard box.
See http://www.elevator2010.org/site/primer.html and http://www.liftport.com/faq2.php#science2 for starters, Google for more.
What really makes sense is an infrastructure that makes getting people and payloads in particular to and from space cheap and reliable, even ordinary. The only chance for that right now is a space elevator.
You have a 3% chance of death flying on a space shuttle. That's an incredibly poor record, and incredibly expensive.
Lose Weight and Feel Great with Isagenix
Since the Moon rotates only once every 29 days or so, the cable would need to be so long that it would hit the Earth, in theory.
Also, in any location other than directly toward Earth or directly opposed to Earth (on the far side of the Moon), Earth's gravity would distort the elevator.
There is a way to place a space elevator on the near side of the Moon, by using the Earth's gravity to counterweight the "top" of the cable, rather than using centrifugal force.
This type of elevator has several advantages:
- It is much shorter than it would otherwise need to be, meaning it uses much less material in its construction, and the material does not need to be as strong as for a longer, non-Earth's-gravity-counterweighted cable.
- The cable goes through L1, one of the Earth-Moon Lagrange points, which is a node on the Interplanetary Superhighway.
- Material mined on the Moon can be lifted "up" the elevator, through the Earth-Moon Lagrange point, then lifted "down" the cable toward the Earth, and deposited directly into Earth orbit.
This last advantage is particularly, uh, advantageous, because such orbits are highly elliptical, and could even intersect the Earth or its atmosphere, which would allow material (e.g., the He3 that you mentioned) to be shipped from the Moon to the Earth without using any rockets at all!The only parts of the Moon that are in constant sunlight are perhaps a very few locations at the poles, which are useless vis a vis a Lunar Space Elevator (although this article proposes a non-vertical Lunar Space Elevator terminating at the Lunar South Pole that could be used to lift water (believed to be located there) into Earth orbit).(Note, however, that it's still longer than the Earth's Space Elevator.)
In fact, such an elevator's cable could be made out of Kevlar!
Search Google for more info.
Those who sacrifice security to condemn liberty deserve to repeat history or something. - Benjamin Santayana
Oh yeah! Iraq! Remember that? That was gonna be a cheap, novel way to achieve fantastic results if we ignored all those doubters!
My point is not to simply smear Instapundit, as he does that for himself everyday, but to point out there is a rather large groups of people in the chattering classes out there who beleave EVERYTHING can be solved by an all out push of all resources..
A war on Cancer/Poverty/Terror/Drugs or some other project to build a huge flipping pyramid of ego.
This is like when Minsky told a grad student to solve the problem of computer vision on summer break....
Sorry for the repost, some of the stuff got cut off before due to my Slashdot noobness. Feel free to mod my other post out of existence.
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/space_elevator_020327-2.html
I still see a lot of comments from naysayers that are based on outdated technology and SE specs. A lot has happened in the last year or two, guys. White papers dealing with everything from cable design (a ribbon seems to be the answer) to weather to electrical charge have been published.
There are still technical problems, some of which we probably don't even know about yet. But there is a design for a cable of 40 - 60% CN that should be strong enough. CN mass production facilities are being built. NASA is taking the concept seriously enough that their guys are writing white papers.
It ain't pixie dust anymore.
Detailed info and links below. http://science.nasa.gov/headlines/y2000/ast07sep_1
"The desired strength for the space elevator is about 62 GPa. Carbon nanotubes... appear to have a theoretical strength far above the desired range for space elevator structures."
http://www.space.com/businesstechnology/technology
"The hurdle to date, Edwards said, has been the commercial fabrication of carbon nanotubes. Both U.S. and Japanese firms, among others, are ramping up production of carbon nanotubes, with tons of this now exotic matter soon to be available. "That quantity of material is going to be around well before five years time. It's not going to take long," he said."
http://www.liftport.com/faq.php
Frequently Asked Questions regarding the SE endeavour, from LiftPort Group
(a LOT of very good info here, here's a couple regarding points I've seen here)
What are some frequent Space Elevator misconceptions?
"Nothing is strong enough to make a Space Elevator."
Carbon nanotubes (CNT), discovered in 1991, are almost certainly strong enough. Theory says that they are 3-5 times as strong as we need them to be, and laboratory measurements of their strength, though very difficult to do and not yet definitive, have shown more than half the strength we need.
The longest nanotubes thus far are measured in centimeters, not kilometers, and certainly not 100,000 km.
We don't need and are not counting on individual carbon nanotube molecules running the entire length of the space elevator or any significant fraction thereof. The individual fibers in a string or rope are only a few millimeters long, yet the rope has a large fraction of the theoretical strength of the fibers. This is even more the case with MOLECULES, several orders of magnitude smaller than a fiber. A diamond is said to be the "hardest substance in the world" because of the strength of the carbon bonds that make it up, but a diamond is not a single molecule. Likewise an SE could be made with CNTs just a few centimeters or millimeters long. (In fact, a CNT several centimeters long is a wonder; they're single molecules!)
"The elevator would be susceptible to a terrorist attack. "
First of all, it's important to point out that there will be more than one Space Elevator. We plan to build a second one immediately (using the first to make it much cheaper) and expect that the second will immediately be used to build a third, fourth, etc. An attack on any one ribbon is unlikely because of the anchor stations' isolation and the relatively small number of casualties that would result. Terrorists are unlikely to be able to break the elevator anywhere higher than 15 km or so; it can then be simply flown back down to the anchor by moving some of the counterweight mass a bit further out and will be back in operation in a couple of days.
The first anchor will be located in the equatoria
No, you're just ignorant. I'll admit that the Patriot is way, way oversold as an anti-missile missile, but if you're in an airplane and someone shoots one at you then you're dead. Patriot was designed to take out Soviet fast movers in the NATO theatre of operations and all of its tests showed that it was very good at that. Taking out missiles is something that it was never designed to do, the Army decided to make modifications to it to try to get some SDI cash in the late '80s. The fact that they had some success is indicative of how well they engineered the Patriot as an anti-aircraft missile.
cheap labor conservatives - they want to keep you hungry enough to be thankful for minimum wage.
> an ego-boosting "been there, done that" trip to the Moon
We're not.
"There are significant differences between the Apollo of yesteryear and the NASA plan of today, Spudis said.
In the first place, the systems making up the vehicles are being designed for maximum leverage: long-life, cryogenic-based propulsion, with potential reuse in space, Spudis explained.
Secondly, the mission is different.
"In Apollo, the mission was to prove we could land on the moon and return safely to Earth. In this case, the mission is to determine the best site to collect and use the resources of the moon and to emplace the necessary infrastructure to do so," Spudis said....
In point of fact, Spudis continued, "Apollo, for all its beauty, was essentially a technical dead-end ... one-use systems, storable propellants, a paradigm of launching everything from Earth."
Spudis told Space.com that this system, as blueprinted by NASA, is designed from the beginning to adapt to a different paradigm: the use of off-planet resources -- lunar-manufactured propellants -- to create a permanent transportation infrastructure in cislunar space, the territory between Earth and the orbit of the moon."