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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."
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
Christ, why does everything we ever dream of nowadays have to consider terrorism as an influencing factor? What is this obsession with living in fear all the time? Have we been so indoctrinated that we now automatically think in these terms? I say screw the "terrorists" whoever they may be. Perhaps if we spent more time dreaming and less time trying to fight fear with fists we'd be a lot better off anyways...
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.
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.
But don't worry -- the engineers looking into the starbridge know about this effect and include it. That's how they get estimates of the required tensile strength.
The Mongrel Dogs Who Teach
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.
The degradation rule is based on small defects in the rope - your rope may be able to hold 500lbs but every 10' has small flaws that weaken that by 25 lbs...
It's the same principle as the chain rule - in that it's only as strong as the weakest link. Think of the rope as a bundle of miniscule chains and you're halfway there.
In theory a nanotube shouldn't have these defects. In practice...yeah right. I figure there will have to be a fairly major degree of over-engineering with regards to stress tolerances in this.
Projects like this are possible - hell even feasable, but humanity needs to pull it's finger out of it's ass to get these up and running. It's really simple - barring a sudden discovery of practical anti-gravity or some other esoteric technology we have until the fossil fuels run out to work out a way of getting bulk loads out of the gravity well. Otherwise, we're gonna be stuck here wallowing in our own filth forever.
We have passed the peak of oil production - easy to get supplies are starting to run low, and the rest of the oil is bound in things like "dirty shale" and are increasingly difficult to access. Time is running short, and posing and posturing do nobody any good.
'Don't worry' said the trees when they saw the axe coming, 'The handle is one of us.'
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.
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.
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.
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.
And don't forget it'd be a tremendous icon of Western achievement. You'd better believe everyone in the US, or whatever country eventually builds one, would be proud as hell of it. The media would be going on and on about how it'll usher in a new age for mankind, and so on, and so forth. If terrorists could somehow take it out, wouldn't that have tremendous psychological value? Remember that they chose the World Trade Center and Pentagon to strike at us, two (or three) buildings that symbolized, to them, everything that's wrong with the US. Wouldn't a tower that reaches into the heavens (hello, Tower of Babel?) symbolize that even more?
It's quite reasonable to take terrorism into consideration when designing a structure. As long as you don't let it make the decision for you. Saying "We'll increase the no-fly zone from five miles to twenty five to give us time to shoot down hijacked planes" is good planning. Saying "We just can't eliminate the possibility of terrorism, let's just not build a space elevator" is not.
Because a rope is not a totally solid system the fibres can and will slip against each other . If a fibre has a 1% chance of having a flaw in a 1' length, it stands to reason that a 100' length has a good chance of having a flaw somewhere along it's length - 73% to be precise. If your rope has 100 strands then 73 of those strands have a flaw. The more flaws you have, the more chance of several flaws close enough together to seriously compromise the strength of the rope.
It's all about probabilities and statistical averages. And yes, that weight of the rope increases as the length increases, but the weight of the rope is usually trivial compared to the usable loading.
'Don't worry' said the trees when they saw the axe coming, 'The handle is one of us.'
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?
Charlie and the Chocolate Factory was teh awesome!
"Come with me, and you'll see.... A world of pure imagination...."
How can you dis? You got a beef with an oompaloompa?
Sleep is futile.
Nothing except the rest of the universe. Or are they adding that in later?
"Give a man fire, and he'll be warm for a day; set a man on fire, and he'll be warm for the rest of his life
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.
Theoretically, if you have a large enough mass on the other end, these external forces should be relatively negligible, and it wouldn't take that much to counteract it. Mind you, I still probably wouldn't want to test it out myself. ^^;
Sent from my computer.
Now GET OFF MY LAWN!
For the same reason that all software has to be secure these days.
http://blog.nexusuk.org
Harsh? Yeah.
--- Ban humanity.
It is not necessary to use a heavy mass at geosynchronous orbet. Instead, make the cable twice as long, and put the center of mass OF THE CABLE at geosynchronous orbit. That way you get extra-orbital launching basically for free.
Did you mount a military-grade, variable-focus MASER on an unlicensed artificial intelligence?
Offtopic:
Remember The Oklahoma Bomb?
Who are "us"?
Who are "them"?
I'm from Argentina: Tango, Asado, Mate, Gaucho, Maradona, YPF
Actually, it wasn't. My first thought was, "cool", but hey...
What really irritates me is that this fear of terrorism is so unreasonable. It's almost akin to the "Won't someone think of the children scenario". The US has been the target of relatively few domestic attacks and of those, one was carried out by a US citizen. Despite this, the fear of terrorism has pervaded the national consciousness so fundamentally that any discussion is now subject to these apocalyptic "what if?" scenarios.
Yes it would be a very bad thing (tm) if someone crashed an airliner into a space elevator, but when that progresses from being a notable, if incredibly unlikely concern, to a point where such fear of the irrational drives society itself, then who cares what the "terrorists" do, they've already won. Of course we should build with the lunatic with a cause in mind, but build we must. This realisation is slowly being eroded. There is a phoenix risen from the ashes of 9/11 filled with hatred and fear, and it is a frightening beast indeed.
Europe has had to live with this for far longer than the US, yet they live in a far freer, far more secure environment than we could ever hope to have. I re-iterate, screw the terrorists. It's the only way we all win.
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).
No to mention the fact that if the nanotubes are strong enough/thin enough (you get the idea) any plane crashed into them will just get sliced in two. i.e. Flying a plane into it would be akin to attacking a cheese wire with a cheese !
Sky subscribers are morons. They pay to be advertised at !
And what if the tether breaks and drops on Earth
1. Everything above the cut would stay in orbit. Everything below the cut would fall to Earth. The base will be on the West side of the Atlantic Ocean and will therefore have hundreds of miles of water to its East. Most of the dangerous things that can cut it are in LEO, which is less than "hundreds of miles" away. So more than likely everything that falls to Earth will fall into the Ocean.
2. Just because the cable has high tensile strength that doesn't mean it is indestructible. You can bind a person's hands with speaker wire and no matter how strong the person is, they wont be able to break free. But that doesn't mean the wire is magically indestructible. It's just wire.
3. In the current issue of Discover Magazine, the concept they write about calls for a cable a few feet across, but only as thick as a sheet of paper. I don't know why so many people assume we are talking about an elevator to lift humans. The first several incarnations will be for light cargo only. Anyway, a cable as thin as a sheet of paper will mostly burn up as it falls through the atmosphere. If any of it survives, it will be shattered into pieces (not together as a whole cable) and will have the same terminal velocity as a sheet of paper. It will just flutter to the ground without hurting anyone. If you are lucky enough to live in the debris path, you can collect the stuff up and sell it on ebay.
So many people make the mistake of assuming that there is some horrible danger that only they will recognize. As if hundreds of scientists around the world are diligently studying this and then Frans Faase of slashdot comes along and says, "what about this problem here?" And all those scientists will just throw up their hands and say "oh god, we all have PhDs but we didn't think of that - we aren't as smart as Frans." Right.
"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.