h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Sigsfried, are you saying you can't have a geostationary orbit in certain locations? Why?

The Geostationary orbit must be over the equator. Otherwise it will appear to wobble moving from above the equator to below it and then back again.

From who's perspective is the orbit wobbling? The earth observer, or a 3rd observer in space?

You can have a sort of space elevator known as a "space fountain" anywhere, but need a continuous supply of power to stay up. It doesn't rely on compressive strength and does need a big railgun pointing straight up. It's a less realistic possibility than the dangling cable concept for all sorts of reasons, although it might actually be the one that gets built first because you could build one in Nevada.

SoRB

Here are the countries that the equator passes through.

http://worldatlas.com/aatlas/newart/locator/equator.htm

Out of those I'd say a country like Brazil or Kenya would be a good place to build one, yes the political infrastructure is poor, but I think that is mainly because (especially in Kenya) the majority of the population live in poverty. The cash a large project like a space elevator could bring in would really help to lift the nation out of poverty.

However the 'best' place to build one would be on one of the islands near to the pacific republic of Kiribati.

http://www.cia.gov/cia/publications/factbook/geos/kr.html

Near to Kiribati are a number of US held Islands like Jarvis Island, although they are small they would be ideal even if they did need a lot of infrastructure like port facilities and an airport. The other advantage if that they are relatively near the islands of Hawaii so could be protected by the Pacific carrier fleet.

Ther is an excellent sci-fi murder mystery set around space elevators and at the end of the book there is an explanation of what materials would need to be used to create them and as far as I can remember they are not too wild. There has also been a paper written on the subject.

It is all to do with tensile strength.

The novel is called Spider by Charles Sheffield (1979).

Well worth tracking down.

Also worth getting the title right. It's "The Web Between The Worlds". (Or is "Spider" an alternative title?).

Arthur C. Clarke also wrote a book about a space elevator at around the same time entitled "The Fountains of Paradise", and the Star Trek:Voyager episode "Rise" was set on a climber module. Can't think of many other major sf uses of the concept though. Anyone else?

SoRB

http://www.isfdb.org/cgi-bin/title.cgi?875

I think the idea of a floating platform in the Pacific as the surface anchor might be preferable. It would have to be pretty heavy but if you can build a 40,000 mile long cable and stretch it into space you could easily build a half million tonne floating island. As the ascent vehicle climbs the cable it would gain a huge amount of angular momentum so some movement at the base might help reduce some of the stress in the cable.

The orbiting anchor would have to be pretty heavy too and most schemes suggest capturing a convenient passing asteriod and placing it into the correct orbit. I imagine it would have to be reasonably geosychronous to reduce excessive cable stresses but some leeway might be acceptable. It would also require a decent propulsion unit in order to compensate for the momentum transferred to each payload. It might of course be possible to provide power for this from the ground.

F

I think it is the alternative title. Now I remember 'Web between the Worlds' is the name of my copy.

Spider is the name of the extruding device that creates the elevator.

Loads... Pretty Dure Kim Stanley Robinson used one in her Mars series - but it did feature mainly 'cos it collapsed/was blown up, and wrapped round the planet a couple of times....

As to Geosync vs GeoStat - if the upper end wobbles a bit (in a figure of eight, as I believe a GeoSync that is NOT GeoStat does) that shouldn't be too big a deal - actually it might be quite desirable, as then there it may be "easier" to steer it out of the way of space debris...

As to best place for ground station - there is some debate - one serious effort suggest the best way to "get this off the ground" (if you'll exceuse the pun) is to send up a space shuttle or two, with (basically) a large cable on a drum which unravels both ways (from a hohmann orbit IIRC) this is then tethered to a floating platform (which could, in theory, move out of the way of any "threats" (e.g. a storm)) this thread would then be reinforced by robots climbing the thread pulling up more thread as they go - eventually making a decent sized "rope" of carbon nano-tubes... (they would be powered via lasers from the ground station) --- apparently this method (probably without the robots - although I don't know) is how the cables for suspension bridges are put up...

This guy (Edwards IIRC) reckons this could be done by 2018...

Yes, it did appear in the Mars series - as was already mentioned, the security aspect of it would need some consideration.

Oh, and Kim's a he by the way.

Sorry, that should have been 40,000 "Km" cable.

Still, it's hardly rocket science, is it?

F

Traveller in Time waiting until evening
"Must be a spectacular view, a 40 000 Km lightning rod

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