5 replies to this topic

[planetp]

For those of you who haven't heard, there is a new space elevator company, High Lift Systems.  They are betting that mass produced carbon nanotubes will be readily available within the next 10 years, making a space elevator both economically feasible and desirable.

Either way, I'm excited about space again, because despite all other indicators aside, space migration might actually happen en mass in my lifetime (assuming no life extension benefits).

Paul

Planet P Blog

[pulsar]

hmm i was only 7 when this thread was made ._. they haven't made one yet and i doubt they would in 3 more years :(

[niner]

Ha ha.  "Prediction is hard, particularly of the future."  (Berra)   I think we'll have a space elevator some day.  It sure as hell won't be in three years though.  It will probably be technologically possible before it's financially possible.  It will have to compete with alternatives like chemical rockets and space planes, and there will need to be a compelling economic model, or else it will only be done by a government.  Maybe a non-democratic one, like China, since they can take the long view, not having to worry so much about getting reelected.

[A941]

I wonder if space-tourism will be boosted through that?

Would it be possible to travell to the moon with a space elevator?
No, not with one and the same, but would it be possible to leave earth with one, be "tossed" of in a Space-shuttle-bus and catched with another elevator-station so that you could descent safely to the moon surface?
Or could you land on the moon without such aid?

[Clifford Greenblatt]

An alternative to the space elevator that I have been thinking of is a vacuum shaft. As far as I know, the Cape Canaveral launching site is not far above sea level. A much higher launching elevation would save a significant amount of rocket fuel. A long shaft deep into a mountain could permit magnetic acceleration of a rocket for a few miles before burning any rocket fuel at all. The thinner atmosphere at the top of the mountain would also reduce air resistance. A 50 mile high pyramid with a magnetic propulsion shaft could get the rocket to a very high speed before burning any fuel. At a 50 mile height, the atmosphere would be much thinner than at sea level. The shaft could be at near vacuum pressure to greatly reduce losses due to air resistance. However, I do not know how the economics of a 50 mile high structure would compare to the proposed space elevator, which would be more like a very long and strong rope into deep space.

[cryonicsculture]

Why build up when you can build down? I think building into a mountain would be best so long as there was stability. Mt. Everest is less than 6 miles high, a 50 mile high pyramid would be like building 1000s of mountains and probably take a considerable amount of time to build. Building a mega city from scratch to be like a pyramid with many structures supporting larger structures to contain the vacuum tube at the center would be necessary to have any kind of economic feasibility. I'd just dig as deep a hole as possible and then top it off with a conventional structure to get it a little bit higher. Better yet, build it into a mountain from some old mine shafts that could be used to load the shuttles. Initial vacuum or near vacuum could be achieved by pumping water melted from the ice cap into the tube which would be deeper (or just terminate into a much less narrow space at its depth) than the volume of water used and contain a drain plug. Vacuum generators could then be used to top off the vacuum and be powered by a series of hydroelectric turbines from ice melt and a bunch of nuclear reactors (lots of energy required to reach escape velocity) which would serve dually as the power for the electromagnetic propulsion. Near the tip of the pipe a high speed "vacuum damn" would be engaged just prior to another one opening at the top to release the payload thus preserving as much vacuum as possible. A series of these "damns" could be used to allow larger or smaller payloads and provide backups in case one fails to close. The magnetic system would continue post vacuum to ensure the change in air pressure wouldn't misdirect the payload. Much smaller rocket stages would then be used to achieve the 25,000+ miles per hour escape velocity required. Breaking inertia wastes a lot of energy.

It looks like all of the largest mountains are in east Asia, so it looks like it will be China, India, or Russia who will have the skill and best mountains for it. Though I guess having a high plateau is more important than peaks, so it it's probably a bit harder to determine where the best launch site would be. I could think of a few more unconventional means requiring much less energy too. Don't forget there are limits to how many Gs a human body can endure. I think that's why we have roller coasters. I imagine they boost bone and tissue density.

Oh, hey Cliff, check this out: http://www.longecity...00-mile-radius/