Space Elevators

[Icosahedron]

Just a couple of thoughts: a few 'emergency vehicle' grav tugs tethered to the cable could take off in the event of a collapse and support it, gently lowering it to the ground.
Elevators might support an artificial ring structure (see Ringworlds thread) and if my thought experiment is correct, that could be placed much closer than GS orbit.
Am I right in thinking that the forces involved would be smaller on a smaller world?

 

[atpollard]

Am I right in thinking that the forces involved would be smaller on a smaller world?

Yes. The forces involved will scale with mass and gravity and small worlds tend to have less (assuming that you do not have one of the tiny worlds with a "neutronium core" that allows it to have normal gravity and a dense atmosphere that Traveller is famous for).

Remember, however, that it takes less energy to reach orbit from a small world by other means as well. A big steam catipult might be able to throw cargo into orbit cheaper than an elevator.

 

[BlackBat242]

Or maybe the world is run by a government catering to the views of extreme environmentalist/techno-paranoids, and has banned the use of any endo-atmospheric transportation that releases any by-products... including radiation (which includes artificial gravity waves, electro-magnetic fields, etc).

Thus, all transport is by electric trains and other centrally-powered systems (with heavily insulated "in-roadbed" conductor strips), and by vehicles with 100% self-contained power systems (picture a battery/fuel cell-powered lifting-body airliner).

Your grav vehicles are highly illegal, so the cheapest "surface-to-orbit" transport is the beanstalk!

 

[Icosahedron]

Just found this posted on another group, thought it might interest some of you:

http://www.orionsarm.com/tech/Orbital_Rings.html

 

[spank]

Heat sink

Another possibility is that the elevator functions as a massive heat sink, technology also creates heat as waste, so a lot of technology on a high pop world might lead to warming problems. Or a tidally locked world near the sun. The heat difference between surface and orbit might even serve as the power source.

 

[BlackBat242]

Hot gas travels up the beanstalk core (spinning turbines as it goes), condenses in the "anchor", then drops back down tubes spaced around the shell... with the space between used for transport.

 

[Icosahedron]

Not sure whether the heat pump would work in practice. Three things occur to me immediately:
1. The gas might condense long before it reaches the anchor, perhaps even before it leaves the atmosphere.
2. There is a temperature inversion layer in the upper atmosphere, where the temperature increases with height, this might adversely affect the flow.
3. Once you reach the orbital anchor, conduction and convection are no longer useable - all of your 'condensing' must take place by radiation.

 

[spank]

Btw

I found this poking around today.
http://www.tcsdaily.com/article.aspx?id=102407b

 

[aramis]

I found this poking around today.
http://www.tcsdaily.com/article.aspx?id=102407b

Nice bit, that, thanks.

 

[galenbd]

1. Legacy. The elevator could have been built in the timeframe when grav tech was not yet known.

2. Cost. The elevator could still be used for commodities that garner very little profits. So low cost elevator rides are better than grav transport
The elevator cable should generate electricity which would make it's use exceptionally cheap
Also, the cost of dismantling the elevator could be fairly prohibitive compared to maintanence.

3. Traffic Control. On high population planets, regulating traffic flow would be a pain. If ground to orbit transport were limited to using the elevator, more space would be available to local transport. Reducing congestion.

Galen

 

[Andrew Boulton]

Speed is a problem - it takes *days* to reach orbit.

 

[spank]

Cost

Cost might be a very good reason to have one in a campaign, When I worked for the grain mill there where 3 ways to ship grain,

1) a Truck, easy, quick, ubiqitous.

2)The Rail, cheaper than trucks; If you loaded a large enough, number of rail cars; 40, you did not have to pay a charge for breaking the unit. If you loaded them in less than 48 hours you did not have to pay for rent on the railcars. It could be very cost effective.

3) Barges, for cost nothing could beat the river.

Maybe the Elevator could be veiwed as analogous to the river. Not very fast, only moving between two points, and absolutely the cheapest thing going.

 

[Maladominus]

It was built at a lower TL and still exists, just upgraded through the years.

True enough. Although at much higher tech levels, the society might consider it 'too obsolete' (and too costly to maintain) and the planetary administration might consider dismantling it. However, many citizens might oppose dismantling an old space elevator... because after a few centuries, it would then become a nostalgic historic landmark. Thus, dismantling a historic space elevator would be as unpopular as say.... dismantling the Eiffel Tower, or dismantling Big Ben.

Another "issue" is that the space elevator, especially one that has become an historic landmark, would always be a juicy target for terrorism. The only way it would survive for so long is if that planet was POLITICALLY VERY STABLE and therefore had minimal presence of terrorism. Also I agree with the point that a beanstalk is more practical (if it can be considered practical at some point in tech level) if constructed on a smaller planet rather than a large one.