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Notes From 3rd Annual Space Elevator Conference
colonist writes "The Space Elevator: 3rd Annual International Conference was held recently. Blaise Gassend, a PhD student at MIT, took notes. The main obstacle is still the material: transferring the strength of the nanotube to the ribbon. Other topics include: the nanotube tether Centennial Challenge; Elevator 2010, a challenge for a 250 kg climber to climb a 16 km tether; objections and refinements to Bradley Edwards' design; non-equatorial space elevators; replacing the term 'space elevator' with 'space bridge'; testing the space elevator material on cable cars; science; defense and economics."
This will change everything. Transporting to space will be (relitive to rockets) DIRT CHEAP. Props to them for their vision and their crazy idea that just might work.
i always thought this was a cool idea, anyone remember that really weird book about this? that rocked. if you still dont get the point its that there will be a space station at the top and the elevator can shuttle up space ship parts and people. and i hope they have at LEAST polyphonic elevator music by then as all the current stuff sounds like monophonic ringtones on an old kyocera cellphone.
This page seems to have some good links. Just check out the bottom of the page as it indicates if you're new to the idea of space elevators.
How on earth are they going to cope with the wind forces, the jetstream, gravity, the earths spin, earpopping, in transit entertainment, lightning, costs, kids, aliens, terrorism and the fact that their's nothing in space to go up to yet.
P.S.
EMACS already does this.
May the Maths Be with you!
ISS is at about 400Km.
Jeroen
Secure messaging: http://quickmsg.vreeken.net/
Wikipedia have a very good article on space elevators
or don't.
I can just see this thing, composed of composite carban nanotubes a million miles long, stretching into the atmosphere.
How are they going to design it so that a bomb can't destroy the precious tether?
Its not space we haven't conquered but our violence.
ls
The point is that it's an extremely energy efficient way of hoisting stuff into space (in theory).
Better to have a comparably near zero cost elevator than spending gadzillions launching a moonbase into space piece by piece using rockets.
The space elevator is a great idea but no human has the mental strength to listen to elevator musak for the length of time the trip will require and still retain their sanity.
Do not try to read the dupe, thats impossible. Instead, only try to realize the truth
What truth?
There is no dupe
I think that it should be taken into consideration that almost every major project of construction was deemed impossible. Very good examples of these are the famous Golden Gate Bridge and the EuroTunnel. Everyone said it was impossible, yet they were completed. As technologoy in this area continues to develop, I think that this may be able to become a real and practical idea sometime down the road. It may not be possible now, but in ten years, who knows?
That's because it's so expensive to get stuff up there. A space elevator would solve that (albeit at great initial expense no doubt ;)
Boffoonery - downloadable Comedy Benefit for Bletchley Park
Ursäkta, men jag fattar INTE vad du säger?
SIG: TAKE OFF EVERY 'CAPTAIN'!!
Tower of Babel? Whats that? (serious)
I believe the point is to make access to space economically practical. Burning massive amount of fuel is pricey and pretty bad for the environment. If we really want to be doing stuff in space we either use space elevators or wait for someone to invent anti-matter drives or something.
---
We spoke for about a half an hour. I don't recall a thing we said. - Colorblind James Experience
And then you get modded up by others who doesn't keep up?! :-)
Please RTFA/RTFM etc.
Karma: Excellent (My Karma? I wish...:-( )
It has been done in some of the older work. It's not as bad as yu think.
It just doesn't feel like bona fide space travel to me.
The owls are not what they seem
Blaise Gassend's page mentions Andrew Price's list of alternative names:
space bridge
space way
space rail
'Space bridge' got the most approval from the audience.
well, in case you're not joking... How the hell would you gather it up and then, having gathered it, how would you bind it together so you could attach the tether to it?
You know, having typed that reply, I really, really hope you're waiting to be modded funny...
---
We spoke for about a half an hour. I don't recall a thing we said. - Colorblind James Experience
It's a really long cable that's held up by the centrifugal force created by the Earth's rotation. An elevator theoretically climbs this cable into space. Unaddressed are the problems with it batting down any non-geosynchronous satellites or the way it would wrap around the equator when it tries to lift any significant mass (most of orbital launch acceleration is horizontal, not vertical).
Forgive my ignorance, MEMS and Nanotech has fascinated me for a while, but I don't know enough of the math behind them to tell if this is true. My grandfather, rest his soul, once told me of something called the Sailor's Rope Rule, which effectively says that the weight a rope can support is diminished by its length. Thus, a 500 lb. rope might support 500 lbs when there's less than a foot or so in length between the pully and the weight, but might only support 250 lbs when there is a good 100 ft. or so... The actual support degradation of course depends upon the width of the rope and the material the rope is made of.
So what I'm wondering is, does the same apply to the weight supported by nanotubes and other molecular chains. I figure it has to be less of a degradation due to the ionic bonds involved, but it would seem to me that, unless some Quantum rule is involved dealing with extremely small-scale weight supporting chains, that they might never overcome this problem due to the sheer thinness of the tubes, chains, etc. It might be extremely strong material, but if it's width is only a few atoms wide, wouldn't this material be, at least in single lengths, more or less useless by the time it got to a respectable length? This is, of course, excluding bundles, which make the most sense, I'm really just curious if the same rule applies to nanotubes as applies to rope.
-The Libra
"Please be patient--The future will begin momentarily."
Not in the fairytail....
But there is archeological evidence for a lot of towers in what is now Iraq and Iran.
Among them some very big ones in babylon.
Jeroen
Secure messaging: http://quickmsg.vreeken.net/
Remember, Strong != Heavy.
I'm not an expert, but, IIRC, Carbon Nanotubes are very light (there was a plan to reduce a light infantry loadout to 60lbs.), and suitable for armour.
I heard about them a long time ago, so my memory might not be right.
I realise this is almost certainly a troll, but hey, any excuse to add actual information to the discussion.
The Tower of Babel is a legend from Christian mythology. In the very early days of humanity, it goes, people only spoke one language. They decided to build a tower that stretched all the way to heaven. God thought this was presumptious, and prevented the construction of the tower by cursing the people so that they spoke different languages and could no longer understand each other.
Lots more information on the appropriate Wikipedia page. (Including a copy of the King James version of the legend, and information about the real tower.)
Fortunately, as was recently pointed out in an article in Time magazine, European continent has become mostly "post-Christian" these days.
The owls are not what they seem
Sorry. It was funny.
Karma: Excellent (My Karma? I wish...:-( )
16km is a little too high for a helicopter (they top out at about 7-8km), but it's well within the reasonably altitude range for a large helium baloon.
Some people believe in the strangest things.
Baloon? http://vpizza.org/~jmeehan/balloon/
If amateur home made ballon gets 79 809 (feet / kilometer) = 24.3257832 km then multimillion funded carbon nanotube project could make or buy a ballon that could work as counter weight. The problems from winds maybe dealt with small jets attached to it. And problem with fuel... Hmm use another balloon for refuelling. And make balloon REALLY big, as the weight of balloon and the surface area for wind grows R while lift grows R so you could get better fuel ratio for bigger balloons.
Emacs is good operating system, but it has one flaw: Its text editor could be better.
According to new Nasa research http://www.nasa.gov/news/highlights/index.html they can fully fund a new US$2 billion research project by selling the franchise to the revolving restaurant at the top and logo placement along the length of the ribbon itself. Already, they have received competitive bids from Chez Panisse, McDonalds, and Bert Farnsdale's New York hotdog stand. This is the start of the holy mothership of bidding wars.
consider coffee a lubricant that helps one penetrate the coding zone
So, by all means, let's just cower in our houses and wait until the magical day that everyone lives in peace and harmony with one another. That'll never happen. As long as there's people around, there will always be disagreement. There will always be dissention and hatred for others and their ideas/ideals and there will always be people willing to die for those ideas/ideals. You are correct, the answer isn't more guns, but I don't see anything wrong with creating a strictly "no-fly" airspace around the structure encompassing several hundred square miles and the installlation of several anti-aircraft batteries (and anti-ship, too) to ensure the safety of the space bridge. If the space bridge falls, it'll fall into the ocean, where most likely it will create more "reef" habitat for the fish. Hooray for the fish in the long term.
If you were me, you'd be good lookin'. - six string samurai
are you out of your mind or just lost the touch with reality completely??
you won't EVER create such a world, there's always going to be someone wanting to spoil the party for the rest(US has even domestic troublemakers). so if you take the attitude that you won't do anything before they're settled down... guess what? you'll end up doing nothing.
world was created 5 seconds before this post as it is.
Been Done: Kim Stanley Robinson in the novel Red Mars which is the first of a trilogy. Green Mars and Blue Mars finish the series.
Nothing in the world is more dangerous than sincere ignorance and conscientious stupidity.
Since then, and particularly since Everest was conquered and modern aviation and space flight have developed, god keeps on moving Heaven higher and higher up since the old "many languages" curse has been quite successfully worked around. Every time astronomers build better telescopes, god just keeps on making heaven ever higher, and inventing new and exotic objects for us to observe.
Stick Men
Not insightful... just flamebait... Are you also concerned about terrorist attacks on satellite launches or the X-Prize?
We're talking about an isolated platform in the middle of the south pacific ocean with nothing around it for hundreds of miles..... there have to be better targets for a terrorists with ICBMs at their disposal.
Get real... this is not political.... and it is virtually isolated from any sort of assault, whether it be from China or from Osama...
The only reason the towers were vulnerable is that they were within range of a very short sighted attack... which had no impact on our security, our national security... but only caused devastating damage to innocent families.
A fool throws a stone into a well and a thousand sages can not remove it.
The Spaceward Foundation is creating the Elevator:2010 program:
If we suddenly have 100 miles of superstrong material slamming down at hypersonic speed, it's going to be extremely bad - somebody ought to calculate how many Teratons of TNT that corresponds to.
Just about 0 Teratons of TNT IIRC. The carbon nanotube ribbon proposed doesn't weigh much and has awful aerodynamics, and for the most part would just flutter down. And that's only the part below the break point, which is going to be pretty low, if it's planes were worried about.
Assume we have that 16km long fiber and solved the problem, that the fiber won't curl up around earth.
We lift up some cargo to the remote point, let it rotate until it faces the desired destination -- and then cut off the fiber and let the cargo flow accelerated by earth rotation. Might be interesting for probes where travel time is not a real issue.
And if we do it with lot/heavy enough stuff, then we even get longer days as a side effect :)
</sci-fi mode>
They have to be to hold the darned thing in place. I doubt something as feeble as a passenger plane crashing into it will do much damage other than making it vibrate for a bit. I don't envy the people on the plane, though.
Stick Men
If we suddenly have 100 miles of superstrong material slamming down at hypersonic speed, it's going to be extremely bad
It'll be more like a 100-mile piece of paper fluttering to the ground. The ribbon will be extremely light. It needs to be, or it can't hold up its own weight. Why don't you go read the Space Elevator FAQ before displaying your ignorance?
Any sufficiently advanced libertarian utopia is indistinguishable from government.
Heading Notes from the Third Annual Space Elevator Conference
AND
Below Keynote speaker, John Mankins line says
Projector died. Talk went on without it.
haha
Striving to be common...
http://www.thebps.com/backgrounds/Elevator_1024x76 8.jpg
Well there is disagreement and there is terrorism. The two are not the same.
Even with a no-fly zone it would still be relatively easy to take down the elevator, think missile.
More probably the first elevator will probably be extremely expensive but within a few decades it will come within the reach or more nations and maybe even corporations and amateurs, like we are seeing now with rocket-based space access (well the amateurs aren't there yet but they are certainly trying).
During the conference there was an article about the toxicology of carbon nanotube. Apparently they induce brain damage in fish and mice, so the idea of the reef may not work out.
Why don't they just genetically engineer giant spiders that also have high IQs. That way they can spin the bridge and kill all humans!
I know you are psychotic, but please make an effort.
About the same as a million piece of cotton floating on the wind.
Everything above the impact zone would hang there, or possibly spring upwards.
Everything below the impact zone would fall at terminal velocity. As the ribon is so thin and light this is negligable, no worse then a leaf falling in Fall, and probably more comparable to a snowlfake. The energy on impact per square mile would be less then a fart.
You'd have to move that junk for starters, which means laucnhing something to intercept it. The counterweight for a very thin elevator is pretty insignificant. You'd have to make several flights to get the ribbon up there in the first place, the vehicle the ribbon is in would act as the first counter weight. You then exapand the elevator by using the first elevator. Say the first has a payload of 100kg, send a 50kg vehicle up with 50kg of cable. The 50kg vehicle adds to the counterweight.
And that is the trick:
You have a big counterweight in geosynchronous orbit. The mass you launch is significantly smaller.
Once it gets up there it is also in a geosynchronous orbit and you simply let go of it and it will stay in orbit.
Jeroen
Secure messaging: http://quickmsg.vreeken.net/
Use a butterfly net and a string bag to put the bits in.
Oh yeah? Just wait 'til the acceleration stops. (duh-dunt--tssshhhh!) Thank you folks, I'm here all night - try the roast duck!
"He who throws mud, loses ground." - proverb
I recall Arthur Clarke pitching the initial concept for a Space Elevator some time back, and revisited the idea in 3001 : The Final Odyssey - in which he depicted planet Earth having a fully functional ( four actually ) space elevator system; which facilitated a subset of human civilisation living in low earth orbits in reduced gravity - thus invoking presumed benefits of doing so.
Anywho. He spoke a couple years ago, subsequent to 3001's release on how at the time of writing, such a feat was nigh on impossible at this stage - as the materials to construct the 'elevator' were yet to be developed. Until now. The carbon molecule Buckminsterfullerene ( C60 ), also known as 'Fullerene', is supposedly strong enough to actually make such a concept a reality - which is in part the reason the space elevator was hurled back into the limelight of late.
I think its a fascinating idea - which until we develop propulsion systems beyond the primative scope of the 1,000+ year old firecracker concept, certainly seems a more elegant way for the species to venture into Space more regulary. Or, at the very least, be the catalyst for what could perhaps become the initial stepping stones to establishing a permanent presence in space which will hopefully later lead to space initiated launches.
What happened to the intermediate designs that don't provide all the benefit but also don't require two decimal orders of magnitude performance improvements? I didn't see anything in the
Brin's electromagnetically boosted tether design (Tank Farm Dynamo, 1983) would reduce the amount of delta-vee needed for orbit, at least allowing for cheaper shuttles. It's not much of a benefit, but we could build it today.
A rotating tether that dipped into the atmosphere would allow much greater safety margins and have a much less dangerous failure mode. You could practically rendezvous with one from an X-prize vehicle, and you wouldn't need to build a climber... just grab the tether, hold on for one rotation, and let go.
The big problem of course is that extra delta-vee isn't free, and the tether would lose altitude every time it's used (this is a problem for all tether designs, really). So, the throughput rate would be limited by the time needed to re-boost the tether between launches: using a high-efficiency low-thrust drive would be cheapest but require the longest "recharge" time.
Longer term, it would get a boost from de-orbiting mass from space: if you return a ship of the same mass to Earth at the same time as you boost one to orbit the net delta-vee is zero. If you have more ships going up than coming down, bring a nickel-iron asteroid into orbit and just feed a chunk of metal that weighs the same as the ship in from a higher orbit, it'd get de-orbited and released at 100km. Make it in an airfoil shape (a crude glider) and you can recover it... just deliver it to an asteroid-iron junkyard out in the middle of New Mexico or something.
THAT would make Rutan's barnstormer spacecraft a stage in developing a new industry, instead of a stunt.
We can't change its name to be a 'space bridge'. If we did, we couldn't have the same hilarious jokes in every Slashdot article about elevator music.
Won't somebody please think of the hilarious Slashdot jokes?
The America / "The West" actually gets off its backside and builds it before China decides to.
Ripping an new rectum in the fabric of spacetime.
Following up to myself: here's a link to a page about a variety of tether-based designs and experiments: Advanced Propulsion Concepts.
The text of Tank Farm Dynamo is online.
Should hope so. If Microsoft ran it, you'd see the blue sky of death far too often
Get paid to search..It's geniune and
And what if the tether breaks and drops on Earth: a wire so small you can almost not see it, but stronger than any other material. It will acts as a knife and cut through almost everything. A sweeping tether could make a whole area unhabitual. Very dangerous stuff.
Something I never heared anybody about: Where does the kinetic energy come from that the cargo gains when ascending into orbit? Somehow the cargo needs to gain a huge amount of kinetic energy, because the top of the elevator moves several km/s faster then the bottom. If nothing compensates for this energy, the counter weight would gradually slow down and deorbit, so there must be some kind of propulsion in the counterweight, pushing it prograde whenever cargo ascends and pushing retrograde when cargo descends. Anybody got more info on this?
Think about it - as long as there are people out there that are willing to fly a passenger plane into a tall building, we shouldn't create an even bigger target.
"Mechanical Engineers build weapons, Civil Engineers build targets"
Seriously, There will always be someone ready to answer the challenge. Brave men and women have always rise up to the challenge, some have given theirs lives.It WILL be done. If not in this lifetime, then maybe a couple of hundred years.
Why? Just like the mountains. Simply because "it's there"
I live in Soviet Canuckistan you insensitive clod!
It doesn't have to hit the ground, does it?
:P)
Still, yeah, hadn't thought of that. That's probably a better idea. (Imagine if you got a team being really ambitious when it comes to speed, ramming into the ISS when they hit the top of their cable.
Before this gets too far, somebody should call NORAD and ask them how many of the 2500+ satellites and other odd bits of junk traveling at 17551mph (LEO) cross the Equator (ascending and descending nodes) and might present a collision hazard. I could be wrong, but shouldn't the answer should be "Almost all of them."
This reminds me of the asteroid/comet problem, the probability of a significant impact might be low, but it only takes one.
The designs I've seen for the space elevators all have a large counterweight in orbit. The centripetal force from that counterweight is what suspends the cable.
If the cable is severed at the bottom, where terrorist attacks can hit it, then it will simply shoot off into space. This would, obviously, be very bad for people ON the cable at the time, but it wouldn't have any other significant effect.
If the cable were severed at the TOP, out in space, then yes, it would come curving down and slam into the earth at hypersonic velocity..... unless they cut it loose from the ground.
They absolutely will have some kind of failsafe release like this. It would take many hours for the cable to fall, and they would know about the problem within minutes. As long as they cut the bottom portion within the safety margin (likely several hours), the cable will still just go spinning off into space. Still sucks terribly for anyone ON the cable, but there wouldn't be much danger to anyone else.
Finally, the cable could be severed somewhere in the middle. The worst possible spot for a cut would be just below the orbital ejection point....the spot at which the remaining cable cannot be thrown out of the Earth's gravitational field by cutting the bottom tie. However, the cable will be thickest at this point, because it will be the area of maximum strain; I've seen estimates that suggest it could be a mile in diameter. It would be exceptionally difficult to cut. But even if they managed it, if they build the cable so that the maximum cable length that can still fall, will fall on nothing but ocean, no big deal.
The ONLY way I can see it being a possible danger would be if they managed two or more simultaneous, complete cuts, which could result in pieces of the cable being flung into inhabited areas, but the number of things that would have to go wrong at the same time would make it exceptionally difficult to do even deliberately. It would be essentially impossible for it to happen spontaneously.
To correct a couple of other responses...
Since the story's in Genesis (OLD testament), it's not just Christian but is also in Jewish scripture. There's probably a version in Islam as well.
The only problem is that earth will slow down if you launch enough mass (provided you don't bring any back down)..... Big deal.
The wrap around myth has been debunked ages ago, do a little google search on it...
Jeroen
Secure messaging: http://quickmsg.vreeken.net/
erm...you do know that what you call an elevator we Brits call a lift? You do? Good, just checking.
Boring Old Fart (40, married, 3 kids...er no...make that 49, married, 3 grown up kids...it's been a long time)
While Arthur C. Clarke certainly popularized the idea of a space elevator in his science fiction novel "The Fountains of Paradise", the original concept is credited to the Russian engineer Yuri Artsutanov, who published it in 1960. See, for example, here
Ubi dubium ibi libertas: Where there is doubt, there is freedom.
There are thousands of other targets which would be far, far easier to hit than a physically tiny (in cross-section) ribbon hundreds of miles off the coast of South America (or Australia, another possibile site that's been considered) - not to mention the ease with which such a target could be defended by declaring exclusion zones around it and patrolling such with warships.
If you're going to launch a missile at it, could you identify where such a substantial missile is going to be constructed and launched; they are not trivial engineering projects. In any case, the missile would have to be targetted very accurately to give it a significant change of damaging the ribbon (particularly if you use your brain and anchor the ribbon at multiple points such that the loss of any one anchor point won't result in the loss of the tether). If these supposed terrorists have nuclear weapons, we have bigger problems.
And a conventional military attack on the ribbon would be dealt with the same way as an attack on any other possession of a soveriegn nation - you go make war on the people who've done it. And while the US has demonstrated that it's not very good at dealing with insurgency, it remains rather handy at destroying conventional militaries.
Any sufficiently advanced technology is indistinguishable from a rigged demo
--Andy Finkel (J. Klass?)
A merry go round is a very bad example for orbital mechanics....
By moving the center of gravity of the elevator around the geosynchronous orbit you can slingshot yourself pretty much to any orbit you want using the pivot point on earth as a lever.
You would need some energy to move the mass around though... (For instance using solar panels on the counterweight to move a small piece of it to a higher or lower orbit along the cable) This energy makes up for the energy you loose by letting the stuff that goes up go.
Its not a problem at all and would be negligable in comparison to the corrections you would have to do anyway to keep the thing in the right spot.
Jeroen
Secure messaging: http://quickmsg.vreeken.net/
My web domain.
In the effort to increase public comprehension of this concept, I offer up "space yo-yo".
The sailor's rule only applies when the rope is hanging down, it has to support its own' weight, yadda, yadda, yadda...
But, you see, this rope will be hanging "up" so to speak, and therefore conveniently bypassing any such rule. If my calculations are correct, since this rope is going in the negative direction, its strength will increase, rather than diminish, by orders of magnitude!
If you don't know what AltaVista is (was), get off my lawn.
I once had an asses debris problem but being on earth, gravity helped keep it discrete. I guess in space the lack of gravity makes it more of a problem. No one wants to share a space elevator with a "happy crapper."
It take more faith to believe in evolution than it takes to believe in God
This is the kind of stuff that Indiana Jones spectacles are made from . Actually, its kind of entertaining watching the currently known truths about Jewish and Sumerican history being woven into a Stargate episode...
A balloon as a counterweight? Am I missing something here? Correct me if I'm wrong but a balloon only has buoyancy when it's in a fluid. After a certain height the atmosphere is too thin to produce any more upward force, no matter how large your balloon. OTOH, maybe you are joking.
Quite an experience to live in fear, isn't it? That's what it is to be a slave.
Harsh? Yeah.
--- Ban humanity.
Oh, it'd be perfectly visible. Yes, the fiber is small, but it will take several billions or trillions of them together to lift anything of any substantial weight. Don't kid yourself, the cable would be several feet in diameter.
- Give a man a fire and he's warm for a day, but set him on fire and he's warm for the rest of his life.
Consider the ultimate composite nanotube material -- stiffness 10^12 Pascal, yield strength 10^10 Pascal. So at-yield, it stretches 10%. The stored elastic energy density then is 5x10^9 J/m^3. This is roughly the same stored energy as an equal volume of TNT (4.1x10^9 J/ton)! Yikes! You can think of the deployed nanotube bridge as a gigantic PrimaCord detonating system.
No matter how you crunch the numbers, an Earth-based nanotube space bridge has to operate very near to outright chemical instability. Yikes!
Bob Forward had the right idea -- emigrate to a planet with less gravity (like Mars, or the Moon). This makes the whole space bridge idea much more feasible.
Sounds like a juicy target for terrorists.
Engineering problems may go away, but terrorism as a form of warfare may not.
Waltz, nymph, for quick jigs vex Bud.
If we suddenly have 100 miles of superstrong material slamming down at hypersonic speed, it's going to be extremely bad
You should think rather of superstrong, superlight tissue paper drifting gently downward in the breeze. And I don't think terrorists are going to be able to fly a jetliner 100 miles up, so we're actually talking only a few miles. However, some thought has to be given how to reattach the thing if it does happen--it seems like at worst it would be a expensive nuisance.
In addition to what's already been posted about it falling like a piece of paper (it'll actually be lighter than paper), it should be noted that unlike the WTC which was between 3 airports (not a no-fly zone) and undefended, the base station would probably be a couple hundred miles offshore, in the middle of a large no-fly zone, with plenty of defence (just park an aircraft carrier nearby).
Current proposals for implementation of the Hans Moravec's original design rely on a hypersonic air-breather of advanced aerodynamic design like the Boeing DF-9 (that exists only on paper).
Can /. readers think of anything likely come along in the near future that could take
paylods to 100km and mach 12?
Probably the same thing that is driving the bureaucrats to make all this noise about space elevators now.
A key to the Rotovator(tm) is getting hub mass in place to keep it out of the atmosphere while it picks up mass from 100km@mach12 -- but that mass can be any old space junk -- at least at the hub where it counts the most for high strength materials like carbon nanotubes. However, you can do a Rotovator(tm) with off-the-shelf commercially available fibers and still have a factor of 2.
Nice thing about Rotovators(tm) is that they can be built with much lower capitaliztion over a much shorter period of time using existing commercial materials. All you need is a bunch of mass orbiting near earth, some quite-doable tethers, and sufficient manuverability and speed in the atmospheric leg to hook up with the tether as it reaches the nadir.
Seastead this.
_The Fountains of Paradise_, by Clarke. A good read, too!
That's why you take it higher than 200 miles, drop it into an eliptical orbit, then correct the orbit with a couple cheap engine burns (very very cheap relative to an all out launch).
It's simple really. As the elevator starts to lean (the beginning of the so-called wrap around), the cable it no longer perpendicular with the ground. If it's not perpendicular to the ground, there will be a tangental force on the ground slowing the earth (immeasurable ammount) and likewise the opposite force on the counterweight speeding up its orbit, correcting the lean.
In reality, you don't get a wrap around, you get a giant pendulum, which is easily corrected. A launch when the pendulum is still or swinging opposite earth's rotation will increase the magnitude of the pendulum swing. A launch that happens when the pendulum is swinging the same direction as earth's rotation will steal energy away from the swing and lower the magnitude of the pendulum swing.
But enough do to mod me to Flamebait -1 above! :-)
Karma: Excellent (My Karma? I wish...:-( )
So Fat Bastard should be getting the call any day now?
"Win treats sysadmins better than users. Mac treats users better than sysadmins. Linux treats everyone like sysadmins."
Why does the Tacoma Narrows Bridge come to mind when considering this "space bridge"? If just one complex force we do not yet understand takes place on this "space bridge" could the results be disasterous? The ribbon would have to be about 22,240 miles long and if that structure got torn to shreads and fell to earth, what would the effects be? Has anyone addressed this question? Would it create clouds of nano tube dust particles we could all inhale? Could parts of this structure fall on populated areas (I believe pretty much half the globe lies within the falling radius of such long structure)?
Hey I'm excited about this stuff, but an engineering project needs to be considered from more than just the successful angle.
What are the potential risks?
Authority questions you. Return the favor.
Elevator? Bah! Think of the workout you'd get taking the stairs.
It is by the juice of the coffee bean that thoughts acquire speed, the teeth acquire stains. The stains become a warning
If I recall correctly, in the introduction or possibly the afterward of The Fountains of Paradise (at least in this edition), Clarke does indeed mention he was not the original idea man behind the space elevator, and goes on to give praise to Yuri Artsutanov.
The Wikipedia entry for "space elevator" mentions, though, that idea was first proposed by another Russian, Konstantin Tsiolkovsky, in 1895(!).
And finally, for those of you who might be interested, this month's Discover magazine has an all-to-brief article on the space elevator. However, being Discover, it is a bit of a fluff piece, but decent nonetheless.
"Yeah, well, Dracula called and he's coming over tonight for you and I said okay."
Elevator 2010, a challenge for a 250 kg climber to climb a 16 km tether
The first time I read that I pictured a 250 kg PERSON in climbing gear. Followed quickly by "Why don't they just use a 250kg mach... Oh"
Conferences like these always give me a lift.
I think the major concern here is not HOW or WHY this structure could fall. There are numerous ways it could fall. The IMPORTANT QUESTION is: "What would happen if it did fall?" This is a fundamental question in any structural engineering project that must be addressed.
Actually, it could be up to 22,240 miles of superstrong materials that come crashing down if it fails. Despite the fact that this material could be light weight so it wouldn't physically harm a person if they got hit in the head with a 20 ft piece falling from space, what could be other consequences?
What about nano tube dust clouds? Assuming this material is strong enough to do it's job, then you also realise that in the event it does snap it would be due to an enormous build up of energy. Once the structure fails it will explode with a tremendous release of this stored up energy. The question then is does it reduce itself into vast clouds of nano tube dust? What are the potential health consequences of such a by-product?
If these scientists/engineers aren't addressing these issues, then we all should be.
Authority questions you. Return the favor.
I wish I had modpoints. Rotovators are indeed much more practical than space elevators. They do not require exotic new materials such as carbon nanotubes. They can be built with cheap materials like spectra or zylon fiber. They are also much shorter (100km instead of 36000km) and more flexible.
This system could double the payload capacity of launchers to geosynchronous transfer orbit or pick up small payloads from suborbital trajectories.
This could be built today. Rotovators are also a very good addition to suborbital space transports such as SpaceShipOne.
Private property is the central institution of a free society (David Friedman)
Someone posted that the ribbon would weigh 7.5kg/km (16.5lbs/km). Geosynchronous orbit is about 35790km. So....
16.5lbs x 35,790 = 590,535 lbs
590,535lbs / 2000lbs = 295.27 tons
So the whole ribbon would only weigh about 295 tons!! Amazing. I wonder if this stuff is even visible - I mean is it transparent? Nanotubes are the new Plastic. The future is Nanotubes!
I for one welcome our new Nanotube overlords...
Authority questions you. Return the favor.
"Elevator 2010, a challenge for a 250 kg climber to climb a 16 km tether"
How about something possibly a bit more realistic, like a 250kg climber climbing a 50 meter tether.
The problem that I have with the space elevator fanatics is that they are setting goals well in advance of the science and engineering which usually leads to disillusionment and could scare away investors in what is a promising area of development. Carbon nanotubules hold great promise, but it is still just promise until they can be manufactured in suffient lengths and with sufficient ease to be practical for any use let alone a space elevator.
If carbon nanotubules are going to be useful, we will see them used as building materials for much smallers things first. Perhaps as robotic tendons, or longer bridge spans, weaved into lighter armor for vehicles... I could think of many important applications which could use shorter easier to make lengths of nanotubules and would provide the neccessary experience to determine if a space elevator might be practical.
Sometimes small steps are big.
Yes! The sub-orbital anvil launcher from X-Industries will be a reality!
O...M... G!!! a 100-mile piece of paper could make a 100-mile paper cut!!! What would we do?!?! Are there any contingency plans in place to handle a 100-mile paper cut? Is there even an order in for a big enough bottle of Bactine?!?!?! And, for that matter, just think how much Bactine would make a 100-mile paper cut sting!!!
Nope, this whole thing's starting to sound just a bit too risky... I say we revisit the "giant rubber band" idea someone had (of course, getting snapped by a giant rubber band is liable to sting quite a bit too...Dang it, why does space travel have to be so risky?!?!?!)
This space intentionally left (almost) blank.
Oh, please.
Why won't you learn English?
*cough* thank you, Google *cough*
The rule probably refers to the fact that the rope has to support its own weight in addition to the mass you're hanging. The longer the rope, the more of its own weight has to be supported.
An equally valid concern to the weight of the longer piece of rope is that any given rope will have some distribution of strengths on a given length, with deviations.
Thus, a 100 ft length of rope will more likely contain a weaker section (as well as stronger sections, but those won't matter since the break will occur at the weakest section) than will a 1 ft length of rope.
A similar argument applies to the distribution of people controlling nuclear weapons!
The larger the number, the more likely that one of them will be sufficiently crazy to actually push the button and make the whole structure collapse.
BTW, you don't want to be anywhere near a tense rope, steel cable, or chain. When it fails, the remaining pieces can whip around at speeds that will cause mortal damage.
"Provided by the management for your protection."
That's a safety feature... if it breaks all the nanotubes turn to soot in a pretty firework show instead of wrapping the planet up like a Christmas present! Pity about the people on board, though.
This is the third or fourth post with someone bitching b/c someone else asked a question or raised a point. Get a life dude. -ron
"Unaddressed are...the way it would wrap around the equator when it tries to lift any significant mass (most of orbital launch acceleration is horizontal, not vertical)." The climber would drift westward, and the net bend in the ribbon would impart a horizontal eastward acceleration. (The angular momentum gained by the climber comes from the earth. ) You can think of the elevator as the world's largest stringed instrument. A climber falling off in mid-climb would pluck it.
I can not believe this is getting so much serious interest by people. And some of the dollar figures being discussed for researching this topic make me want to puke.
Well... let's see.
Carbon nanotubes are a ridiculously strong, ridiculously light material - strong does not automatically equal heavy. In fact, the weight of the ribbon is in the range of 26 pounds per mile or so. Any given chunk of it would fall with all the impact of a piece of paper or length of yarn, unless they balled it up into a gigantic ball before hurling it at the planet.
The cable would be 62,000 miles long.
So what's the cable weigh? The cable weighs approximately eight hundred tons through its entire weight.
So. 2,600 pounds coming down at those kinds of speeds, the impact happening along an strip one hundred miles or less in length. IANAP; I'm sure there's someone else who could determine how many teratons of TNT that corresponds to. It's a wee bit over to the right side of the decimal, though.
-PS
"All that is necessary for evil to succeed is for good men to do nothing." - Edmund Burke
That's no small potatoes, for ultraprecision wonks.
Put another way, if you launched a billion tons a year you would have about half of the effect on Earth's rotation as the Moon's measured tidal drag over the last 30 years.
7.5 grammes per metre, about the weight of a piece of paper 10cm (4 inches) wide. I hate it when someone drops a letter on my head from the top of a building, it's so aerodynamic it reaches a massive speed of about 20cm/second!
Not to knock you off your "Christian mythology" highhorse but since the Tower of Babel story is in Genesis, it's from the Torah and technically rooted in "Jewish Mythology".
Unfortunately, while it's fashionable to throw around terms like "Christian mythology", calling a Jewish story made up will probably just get you labeled as an anti-Semite. Too bad anti-Christian statements aren't treated with the same revulsion as saying Hindus, Jews, Muslims and Buddhists are all living in a fairy tale.
Blaze a trail to the New World
The strongest real carbon-nanotube rope is 1 GPa. Edwards elevator design needs 100 GPa ropes. In Edwards book, "Space Elevators", page 26 he predicted that we would have 100 GPa ropes by 2005 or earlier. We just are not close to this and not moving fast. Last year the record was also 1 GPa.
Now Edwards is predicting another 2 years. He will be wrong again. We had "graphite whiskers" 48 years ago that had 20 GPa and we can not make strong ropes of these yet. These are easier to bind to than nanotubes. So 2 years is just much too optimistic for 100 GPa.
Rockets are so tremendously inefficient because they need to lift all their fuel with themselves. Something like 20% of the space shuttle's fuel is needed just to lift the other 80% of the fuel above the 500-foot altitude of the launching tower. Then you have to spend a good chunk of the remaining fuel just to raise the rest of the fuel up another 500 feet, and so on. It's geometrically inefficient.
With an elevator, as you describe, energy has to be applied both to raise the load's altitude and to get it up to orbital speed. This isn't a trivial problem, but it's solvable with far less overall energy expenditure than rocket fuel. In principle, electric motors can do the lifting work. It's far easier to lift electricity slong a wire to orbital altitudes than to lift rocket reaction mass.
Here's the most relevant quote. .
I remember reading about the Shuttle experiment with the tether, the idea, if I recall, was to see if usable energy could be generated in this manner. Everybody was surprised at how quickly a charge built up and burned out the cable. This doesn't sound good for space elevators!
Any takers on this item?
-FL
However, if you take the train, you go from downtown london to downtown paris. If you're on one of the French high-speed trains, the trip is only about an hour longer than it is by air. Factor in the fact that you can clear customs on the train rather than on the ground after you land, as well as the hour+ drives/cab rides to and from heathrow and charles de gaulle airports, and the train is actually faster for buisiness commuters by at least an hour. Now, there's not many people whose time is worth 149 - 64 = 80 GBP/hour, but they do exist.
There's other reasons, mostly regarding how train travel is generally more pleasant than air travel, and then theres the fact that you can bring your car across to calais from britain, but I found the revelation that the train can be faster door-to-door to be particularly insightful.
">>If we suddenly have 100 miles of superstrong material slamming down at hypersonic speed, it's going to be extremely bad"
That's funny. The proposed space elevator (which uses a paperthin ribbon cable, by the way) has only a tiny fraction of the mass of a single WTC tower.
Something like only 24 tons of material is needed for the initial anchor cable. That's something you can loft aboard in just a few rockets. What's that, one truckload of wound-up starter material that's over 60,000 kilometers long? That's it. Then after that, it's only a few truckloads more of ribbon material, and you're done. The WTC took over 1000 truckloads, the space elevator is far less material.
Space elevator ribbon - It's low density material. Superstrong yes but flexible. Drop a Mylar anti-static plastic bag (for a PC motherboard). That's 1 square feet of elevator ribbon fluttering to the ground pretty harmlessly. The space elevator ribbon will be of much tougher material. However, the space elevator ribbon is actually lighter than that mylar bag!
When a space elevator collapses (which will inevitably happen to at least one space elevator, once they start sprouting up, Murphy's Law is going to always be with us), it'll just mostly flutter down. The stuff in the vaccuum will burn up quickly as they accelerate without friction and hit the atmosphere. Now, the concern is mainly with the lower (atmospheric) portion. Some damage may occur to the platform, and a boat might be capsized if the kickback of the gigantic-rubbery-like "snap" of the most earthmost (lower 10km or so) of cable, hits nearby water with enough force to capsize a small ship. Even so, that may not even happen, because even 100 feet of atmosphere will slow down an ultralight paper-thin material very quickly from supersonic speeds to subsonic speeds. So because of this, ships and platforms are probably going to be very rarely damaged from a falling elevator ribbon! It's not going to be Apocalypse. A falling Lifter will be far more deadly - but far less dangerous than a falling space station or nuclear powered satellite. People are just going to keep reattempting the space elevator, especially if there are successful attempts. The Write Brothers versions of the first few space elevators will definitely have the equivalent of a few biplane crashlandings, a few Apollo 1's and 13's are definitely going to happen, but your scenario is a joke.
To quote the original Bradley Edwards paper "The Space Elevator",
"The segments of the cable in Earth's radiation belts will experience less than 3Mrad per year (energetic electrons and protons) [Daly, 1996]. Studies of epoxy/carbon fiber composites (epoxy/nanotube composites would be expected to be comparable or better) have found them to be radiation hard to greater than 10^4 Mrad [Egusa, 1990: Bouquet, 1979]. This would allow them to survive more than 1000 years in the expected environment"
To survive the atomic oxygen, it was proposed the ribbon be coated with a thin layer of metal (aluminum, nickel or gold) between .02 and 20 microns thick. This would only be applied where atomic oxygen is a likely hazard
Finally, it is understood that the ribbon will degrade over time despite best efforts, due to radiation, electric discharges, micrometeorite damage, fiber/epoxy failures, etc. They talked about a plan to periodically inspect, and, if necessary, reinforce the ribbon with additional strands of material.
Men jag förstår det shit gott ! (och jag år myckett odfattig in svensk ocksa)
Sky subscribers are morons. They pay to be advertised at !
Did you read the whole page. At the bottom he says...
We would be far better off to invest the money into more advanced propulsion systems, like those aboard the non-existent (?) TR3 black triangle. Its time this drive technology was released to the masses that paid for it in the first place ! Such propulsion systems won't just get us 62,000 miles from earth, but instead to other planets.
If the government had a propulsion system like that they would use it for space launches.
Anyway the study I read said it would de-ionize an area a few centimeters around the cable, because air is not that conductive, and the Ionosphere regenerates itself.
Harsh? Yeah.
Effective? No.
Mind telling me how that stops a terrorist intending to ignite an all-out war between the western world and the Islamic world?
And how are you going to convince anyone that you're serious? Coz just sayin' so ain't gonna cut it. Talk's cheap.
--
If the road to hell is paved with good intentions, where does the road paved with evil intentions lead to?
Sorry, but thermodynamically rockets are among the most efficient machines around. They are very good at converting chemical energy to thrust.
;-) to put the pad on and save all that fuel...)
The thing is, they have to take their reaction mass with them.
With an elevator, the elevator cables (and counterweight) are the reaction mass. Don't forget to calculate the energy and fuel required to build/deploy the elevator in the first place. Sure, because it stays there (instead of dissipating like rocket exhaust) it will, with enough use, eventually be far more effective than a rocket.
(Oh, and about that shuttle fuel thing -- that first 20% isn't just to lift the rest of it to 500 feet, it's also to accelerate it to whatever speed it's going at that point (100 mph or so upwards). Otherwise they could just build a 500 foot hill (biggest in Florida
-- Alastair
The window of opportunity for flying airliners into anything closed on 11.9.2001 before the fourth plane reached its target. Let's rather worry about the unknown unknowns.
--
If the road to hell is paved with good intentions, where does the road paved with evil intentions lead to?
I took mechanical drawing during high school summer school, the drafting teacher got to control the radio, his preference was for the "easy listening" station, it was the early 70's, and lets just say whenever I hear "Just like me, they want to be, close to you. Woohoouhhoo, close to you!" all I can think of is 4H and HB leads. It is strictly Pavlovian.
"Say, can you hit #4,427,615 for me? Thanks!"
JET Program: see Japan, meet intere
And just having a look at the modding that's going on, at least one believer in the God that condemns babies to Hell because they died too quickly has mod points. I'm looking forward to metamodding tomorrow. Oh well, suffering is supposed to be good for the soul, or something like that.
English is not my native language and there is ALWAYS a counter weight at end of teather in space in full scale. Uhh balloon creating the upperward force for keeping the teather up. I wasn't joking, only my expression wans't best possible.
Emacs is good operating system, but it has one flaw: Its text editor could be better.
Skyhooks are attached to aircraft, not the equator.
Details here.
It's never too late to have a happy childhood.
> Not stupid, but boring. It just doesn't feel like bona fide space travel to me.
That's the idea. A lot of us *want* space travel to become boring.
It's "exciting" that in 43 years since Gagarin, fewer than 500 human beings have been to LEO or above.
It's "exciting" that we're so thrilled to see Spaceship One do what X-15s were doing 45 years ago (albeit more elegantly, with private money).
It's "exciting" that a Shuttle launch costs $350M-$500M instead of the $10M-$20M hoped for in the 1970s.
Enough excitement, OK?
I'll get me coat.
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
If you build one, you can call it whatever the hell you want to. Until then, it's all wanking. (that means masturbation.)
Why yes, I AM a rocket scientist!
Well lets make SIMPLIFIED calculations... Assume a cubic with 100meter edge. That has volume of million m^3 the air density at target altitude is 1/5kg-0.1 per m^3 [It wasn't clearest graph where I looked the value] Then that sized of ballon can handle 100-200Tons now. Then there is need to stabilize the location of said balloon, in order to test teather. And for that it needs some sort of engine to stay still and the jet engine is not correct choise [ARGH I should of slept more.] But still I think the engine and balloon and fuel will weight a LOT less than the 150Tons assumed lift at the height. Perhaps leaving couple of tons for the weight of teather and 250kg for weight of the climber. Besides balloon made of nanotubes would weight a LOT less than that and the engine and propellers don't weight too much either, nor does the fuel to keep it steady. The height where air is too thin for ANY kind of balloon is over 20 and probably over 30km . And with some nanomaterials there maybe possibility to build even HIGHER climbing balloons.
Emacs is good operating system, but it has one flaw: Its text editor could be better.