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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."
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...
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?
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.