Thanks Neil for doing some of the required calculations.

I agree it makes sense to have the lowest point above the atmosphere ie around 50km above the Earth surface.
As the speed does not need to be so high for the transfer craft something like Vigins Spaceship 1 could be used.

The G forces are not very high ( 10G ) and as the cable is so short compared with the SE , I think it will be achievable with todays technology. Advanced CNT would obviously help.

The docking is seen as the showstopper and I think this is possible as you say with tip guidance as well as accurately calculating the position for the ground transfer craft. It would be a pain if you missed the transfer as the next pick up point will be half way round the world.

I think this could also be used for quick Earth travel. Imagine NY to  Sydney in a few minutes.

On an airless body such as the moon, it could even be used from the ground. It would be like having a teleporter.

I think LEO satellites are probably getting to be past their best years as UAV replace them for ground imaging and communications are avoiding them because of lag.
For TV GEO satelites still make sense as lag is not really such a problem.

This means the other problem of the bolo , is that it will wipe out a large volume of LEO space is becoming less of a problem.
The bolo would make sense for large projects in space such as building a manned spacecraft to explore the planets. Once the spacecraft isbuilt the bolo could be de-orbited (fairy easily as it skims the atmosphere anyway) to free up LEO space again.

Remember the bolo SE will not have these slow speeds. Its main problem will be high G forces if we use a short cable.

Having two elevators with only one being used from the ground makes some sense.
A previous thread mentioned the sky platform where the platform could be supported by balloons/kites or use helicopter rotors. Up to the platform a loop could be used as it is not being supported from GEO.

If several SE were used we could have several shorter and lighter  than the full top to bottom SE and this would allow freight to be moved at different speeds , preventing bottle necks and increasing the total mass being carried for a total SE mass, of less than having just one SE.

My definition of life is self perpetuating complexity.

=====================================================


Examples and special cases
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1) A sterile Ass is alive . Can not reproduce but is still living product of perpetuating complexity.


2) Life does not need to be based on DNA  or even Carbon

3) Life does not require intelligence

4) Life can exist within computers. e.g. computer virus

I agree that a bolo is probably the best solution for Mercury. We can arrange so that the boarding speed is almost zero and it does not need to be very high due to there not being any atmosphere. One bolo will be able to service both polar bases. Possibly using some kind of hook to catch a cable suspended from two towers.
I would think that other than the high temperature this might be the easiest place to build a working bolo system.

I think Titan is another  place we should consider as it has liquid lakes of ethane  and although very cold looks like it could be an interesting place to visit even though it so far away. It is easier to heat up a vehicle than keep it cool.
Can someone provide the value for the rotation rate of Titan to see if a SE is possible.

Helium may become cheap if we sucessfully build a fusion reactor as helium will become the waste after the fuel has been reacted.

I am allowing for taper in my figures, and starting off assuming that the elevator cable is going to be fairly marginal.
Obviously if the cable material comes out really strong with many tonnes of spare capacity we do not need a sky station.
You can not simply say that 25km is a tiny fraction of the length of the cable and can then simply be ignored.
What I am stating is that if your cable has margin to lift a 1 tonne shuttle. Making the cable lift two tonnes means the whole cable needs to be twice the mass.

The weight saved depends on the weight from the ground to the skystation of the required cable including weather proofing , lightning conductors etc.

If the Elevator can lift a shuttle weight of 1200kg and the weight of the cable upto 23 km is 500kg then the total weight of the cable is reduced by 

  1 -  (1200/ (1200 + 500))   ie  0.2941 
                                or as a percentage 29.41%

The advantages of balloons is that if the strenght of the cable is very marginal we can reduce the total weight of the ribbon (because it will be tapered) by a signigicant amount. The bottom of a tapered cable will be the part exposed to a great deal of weathering and possibly will have to be able to withstand lightning strikes.
Having not to suspend weather proofing and lightning conductors from GEO will save an awful amount of weight in the whole cable (maybe upto 1/3).

If we can produce a realy strong cable, we have no reason to worry about this so can do away with the "sky station" for simplicity and cheapness.

The balloons would not be attached to the shuttles , but to a platform at about 100,000ft. It will probably result in cargo having to be transferred at this point between a shuttle from the ground and one to go ot GEO.

http://technology.newscientist.com/channel/tech/mg19926656.300-invisible-nanotube-cable-could-support-a-human.html



10 milligrams per kilometre to lift a human

No worries.
We just build our sun shield to block out most of the Suns heat going to Venus and then wait for it to cool down.
This will be like a reverse global warming and once the atmosphere start turning to liquid and solids it should solve most of the problems.
Could take quite a few years. Anyone know how long if we stopped 100% of the sun ?

It is better to be prepared for a disaster that does not happen than be hit by a disaster that you predictred may not happen.
The best solution would probably be to reduce the growth in the worlds population so that we have a chance to handle all these disasters and oil shortages that are predicted.
At somepoint nature will not give us a choice in this matter and millions are going to die

I am one of the people who propose putting the Sun shield at L1, but I must admit I do not understand how the polar orbit would work.  I have a few questions which maybe someone could answer
1) How far out is it if the orbit takes one year ?
2) Would this be cheaper to reach than L1 ?
3) Is the orbit eay to maintain in the correct orientation ?
4) What percentage of the time is the shield providing  useful cooling ?

A sun shade at L1 would appear as a tiny dot I agree but there is no problem with this and it would stop complaints from people on the ground that they are living in darkness. The cooling on Earth is still approximately the same as in LEO as the partial shadow almost perfectly covers the whole Earth side facing the Sun.

The only sensible way to create the SE is from  GEO down.
You would deploy initially a very light cable both up and down from this point so that the orbit does not change.
You would progressively deploy thicker cable as you spooled out the cable so that the taper was produced.

Once the cable has been fully deployed to the ground you could start sending up climbers with the aim of adding additional fibres to the cable to strengthen it.

Can we also just state that GEO is at 22240 miles . I think some posters are getting mixed up and thinking it is 22000 feet which is totally wrong.