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« New Nano Economy | Main | The Truth About Science »

July 05, 2004


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Mr. Farlops

Yes, it may be that the real hurdles are political and social, but then they've always been only hurdles that matter in the end. For example people may demand safety proofs by using the CNT cable in enormous suspension bridges first before trusting the engineers to build this thing.

This is something I actually think governments should start pushing for. The science is well understood and the engineering is getting cheaper by the day even without mature MNT. It's really just a question of getting the billions of dollars and political will to do it.

I argue that doing this is even more historically significant than landing people on the moon, because it's the only way for space travel to become extremely cheap. Once leaving earth's gravity becomes very cheap, everything else--asteroid mining, building enormous telescopes on the farside of the moon, space colonies--follows.

Speaking as a local who lives near Bremerton, I wonder why Paul Allen spent his money on a jet powered joyride like SpaceShipOne instead of investing a few mil in LiftPort!

Brett Bellmore

Well, for one thing, even if the space elevator gets built on schedule, we'll need rockets for people for quite some time; The elevator, in it's early embodiments, only allows the payload to be lifted at a couple hundred MPH, tops, and it penetrates the Van Allen belt. Which means a very long trip to orbit, with a substantial amount of time passing through a high radiation enviroment. You really want to spend several days to a week, in a lead coffin, to get to orbit?

Only when we can build larger elevators, where you can either use EM induction to lift the payloads far more rapidly, or have substantially larger shielded elevator cars, will the elevator be feasible for lifting humans into orbit.

Doug S

Brett: spending 3-7 days in a lead coffin probably doesn't sound to bad to most that would be going up. Now you have people paying a million dollars to go to the ISS for a couple days, and they have to wait a year or so to be able to do so. I personally would not mind spending a week possibly gazing out a window as the earth begins to curve, or sit and read a book(s), or go over mission objectives. god knows I spend weeks at a time doing less.

A space elevator in my opinion will allow for 2 huge things. 1) unlimited solor power 2) the ability to construct a spaceship relatively quick, larger than any that could possibly be built ON earth. Heck just those 2 reasons I think are reason enough to attempt to build it.

Brett Bellmore

I'll grant you that, I'd certainly volunteer to be locked up in that coffin. But there might be occasions when you want to get into space in less than a week...

Let's add advantage 3: Those portions of the space elevator which are above geosynchronus orbit are moving faster than orbital velocity. Beyond a certain point you exceed escape velocity, and above that, there are altitudes where you can just let go, and be flung off with enough velocity to reach any of the planets.

Of course, you're limited to the plane of Earth's rotation, but a space elevator can provide most of the delta-v for a launch to other places in the solar system, free, once you've built it.

jim moore

I like a modified version of Josh Hall's space pier. A space ramp. Along the equator build a several hundred kilometer tall ramp out of diamond that holds a tube that is a couple of meters wide. The tube is an electromagnetic accelerator that launches spacecraft. You can do the same thing that the space elevator does but with much wider safety margins.

Brett Bellmore

Ok, an electromagnetic accellerator with it's terminus located above the sensible atmosphere, does have certain advantages. However, the intitial investment necessary to build a working system would be MUCH higher. The nice thing about a space elevator is that your first one can be small, and yet immediately useful. New ones can be built in a very short time. Siting is relatively flexible. It has fewer failure modes. (Cables don't buckle.) AND, quite important under current circumstances, the area that has to be secured against attacks is much smaller.

We might see an accelerator type system built after there's a LOT of traffic into and out of space, but it's definately a second or third generation system.

jim moore

Josh Hall estimated the cost of the space pier to be on the order of 10 billion dollars. He used a cost estimation for the diamond at 10 dollars per kilogram.

Tom Mazanec

He also pointed out that eventually a satellite is gonna hit and break the cable.

Chris Phoenix, CRN

If you track satellites, you can move the cable to avoid them, either with mid-cable thrusters or by moving the ground attachment.

Another advantage of the cable: being a lot lighter than a space pier per length/area, if it does fall it won't hurt anything.

They're both cool ideas. But I suspect the elevator will be built first.


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