If the ribbon is cut through the other 99% may survive but would fly off into space.  Unless rescued the passengers and crew would die when their air runs out.

That is a good alternative solution.  Just ensure that the climbers can handle the changeover.

* The SE may not have a tip but it could have two sharp edges.  Even if it is a tube, it is only a narrow tube.
* Since metal towers get hit we would be very lucky if permanent short circuiting worked but we could be lucky.  Graphite is a good conductor so some types of CNT may be.
* Even insulating things like wood and stone get hit by lightning, particularly when wet.  Note: The mining industry needs a strong insulting material, power cables that wear out after 6 weeks must cost them a fortune.
* For movement to work the storms would have to be tiny.
* A ribbon that can take lightning strikes would certainly be a good selling point.  Air ribbon and space ribbon do not have to have to use the same epoxy or coating.

It is fairly easy to find out more about the weather at at SE landing site.  Tether a balloon to a buoy and see what the elements do to it.  The longer we leave any changes the more expensive they get.  Until SE2 is operational replacing SE1 requires a second rocket launch -  very expensive.

An important variable in determining the weight of the bottom of the Space Elevator is the probability of being hit by lightning.  Is it zero or very low?

Genuinely zero means no protection needed.  A very, very low probability of one strike per 20 years means guaranteed destruction unless protected.

An aluminium lightning conductor weighs about 6 tonnes and needs something to support it.

http://www.blackmagic.com/ses/bruceg/EMC/rckt/rocket.html

http://www.alohaowners.com/pages/projects/lightning/lightning.htm

A description of how ratchets work.
http://en.wikipedia.org/wiki/Ratchet_%28device%29

Sorry Neil, no free energy.  There is a great big motor on the winch which is supplying the power to the cable.  The winch motor could be electrical or diesel.  Fortunetly motors is at the anchor are easy to refuel.  I do not know whether the efficiency of the transfer is 50%, 30% or 10%.  My gut feel is that the efficiency goes down the further up the ribbon pair you are.

If there is a way of taping the Earth's rotation for additional power this may keep the running costs down.

By looping the ribbon at both ends Andreas appears to have reinvented the cable car.  Machines with years of reliable service at skiing resorts all over the world.  Our mountain is just a little bit bigger than other peoples.
http://en.wikipedia.org/wiki/Cable_car

A second motor could be installed at the top powered by solar energy to halve the local force on the ribbons.  There is no requirement for the counter weight to be passive.

A loop can be thickened and repaired at the anchor point which should keep costs down.

In the alternative design of two ribbons I do not understand how Coriolis forces would separate the two ribbons but it would save having lots of separators.

Using longitude vibration to lift the climber sounds great and I suspect is a variation on the Archimedes screw.  This has reliably lifted water for thousands of years.  Below about 100 to 140 km the atmospheric drag would be high but a standing wave in a vacuum should be great.
http://en.wikipedia.org/wiki/Archimedes_screw

As for Frank's idea of compressing both ribbons I suspect that we are too near the breaking point of the cable.  To permit compression of the second ribbon the total mass carried would need reducing.

 The force due to the weight of the cable + the weight of the payload + the compression force has to be less than the breaking force of each ribbon.


Frank's second idea of reducing the wear on the cable by adding cargos at random intervals sounds good.  Using a trick from cryptography, you make the length of the cable an even number and distance between the cargos a prime number (or multiple of a prime number).  Providing the length divided by the prime number does not have a remainder of zero the entire cable will be used before any offset is reused.

Using stretched ribbon material as a power source has given me an idea.  By using two ribbons the climber can be carried the entire length of the cable without having a motor on the climber.

Stretching the supporting ribbon strikes me as a disaster in the making – when it snaps we will lose everything.  As demonstrated world wide by elastic bands when things are stretched they break easily.  Separating the carrying ribbon from the pulling/power ribbon means that the only load on the transport cable is weight.  The pulling cable can use its entire stretch to move the climber(s).

The climbers would need two sets of rollers, a set for each cable.  The rollers need ratchets to prevent the climber from going backwards.  The pulling cable is winched towards Earth whilst the climber stays still.  When a sufficient distance has been pulled in, say 50 km, the pulling ribbon rollers are locked and both the climber and power ribbon are winched out.  Repeat until required height reached.

As shown by ratchet screwdrivers the locking of the wheels can be automated.

Specifying which ribbon is the pulling ribbon and which the carrying ribbon is arbitrary so they can be swopped over, simplifying servicing of the Earth based equipment.

In theory such a propulsion system can work after the second fibre has been run out but I would be happier after the fourth – two fibres for each ribbon.  With care both ribbons can be constructed simultaneously.

Removing the motor and most of the photovoltaic cells should reduce the weight of the climbers or increase their payload.  Many missions would not need the lasers to power them.

In the event of a cable being cut it can be repaired by two powered climbers using the second cable.  The climbers start at opposite ends.  The counter weights may need roping together.

If either ribbon breaks the other ribbon can support the climber until the passengers can be saved or brought back to Earth using gravity.  Safe return to Earth would need the direction of the rollers to be reversed and a brake to keep the speed down, the winch would need reeling out.

A double ribbon system can be used to raise unpowered climbers and improve safety.  One ribbon carries the weight of the climber and the second supplies transfers the lifting force from contractions as the winch is run out.

Andrew Swallow

You do realise that a ground winch will half the mass that can be raised by the SE?

The SE is not mass limited but force limited.  (It is just simple to express the force generated by an object being carried as mass/weight.)  The winch is a very large force.


That is right.  When the SE breaks I will just be sad for a few minutes about the waste of what could have been.  They will be unemployed.

With a winch at LEO or GEO pulling up.

A winch on Earth treats the ribbon as a gigantic spring.  The counter weight is brought nearer the planet, payload added and the counter weight allowed to return to its normal place causing the payload to raise.

A motor is still needed on the cargo if it needs to go higher than the pull down distance.

This is also a way of lengthening the cable which saves the cost of a climber.  Climbers are still needed to thicken the cable and to increase the mass of the counter weight.

I searched the internet for lightning conductors.  That site gave weights others did not.  Then I picked the lightest on the page.  The SE will need its own design of lightning conductor.



I believe lightning strikes will be rare.  I do not believe non-existent.  Sometime during a 20 year period an SE will get hit.



The coating to protect against the atmosphere, weather and pollution also adds weight.

Raising and lowering the cable by 50 km will require some fairly sophisticated machines.  Since they are in space they are difficult to repair.

When the ribbon is lowered within an hour even a light wind of 10 knots can push the ribbon ten miles away, in any direction.  That will lead to a few games of hunt the ribbon.



Everybody and nobody.  Plenty of room there for buck passing.  Simply because they are unwilling to accept the blame when it fails does not mean they are willing to give up the power.



Banks have learnt to ask for approvals before releasing money and to demand that anything they lend money on be insured.  The SE will be inspected, probably by someone who thinks it is a large ship's mast or factory chimney – both of which have lightning conductors.



A sky platform will take a significant time to develop.  LiftPort cannot afford to do this after the SE is launched.  The sky platform can be designed and manufactured at the same time as the initial ribbon is made.  The platform needs to be working on the same day that the ribbon reaches the atmosphere.  We are now in the high level planning stage.  Major components are outlined at this stage.

A ribbon material that does not rot, is very strong and is a good conductor of electricity would remove the need for a sky platform.  Are we going to be that lucky?

Do the Sky Platforms need to be manned?

I suspect not, although the occasional visit may be needed.

Functions performed by the Sky Platform

Forwarding climbers from the sea anchor to the space ribbon.
Returning the empty air climbers and farings to the sea anchor.
Rendezvousing downward space climbers with air climbers and sending the assembly down to the sea anchor.
Anchoring the space ribbon.
Supporting the tether.
Refilling the balloons.
Extending the width of the end of the space ribbon.
Performing repairs.
Powering any machines.


The lifting is performed by the balloons, who when properly tethered look after themselves.
If the two ribbons are placed side by side designing machines to swap is possible.  Particularly if given a remote control command.  The operators can watch from the sea anchor using a tv camera.
Anchoring and supporting are passive functions once the initial connection has been performed.
The machines could be powered by solar power, batteries and wind power.  Once fitted that is an automatic function.
Refilling the balloons and performing repairs will need to be performed by people.
Extending the width of the end of the space ribbon will need to be done by hand since the clamps holding the ribbon will need releasing.

We disagree over the weight of the ribbon in the atmosphere.

A lightning conductor for a class II installation could use rope lay copper cable weighting 416 lb per 1,000 ft and be 60,000 ft long.
http://www.ipclp.com/html/conductor_cable.pdf

(416/1,000) * 60,000 = 24,960 lb
or 11,321.6 kg

Eleven tonnes is more than the breaking strain of the initial SE1 and over half the total carrying capacity of the final SE1.  It is easy to see why the unprotected SE are planned for places where there are few lightning strikes.  As the diagram showed it would probably be a sheath rather than cable but it still weights the same, since it is straight up there will be extra CNT to hold the lightning conductor up.  The CNT will also need coating to protect it against the atmosphere adding even more weight.  Aluminium is lighter but it is still too heavy.

We may be able to play games with the rules whilst only LiftPort personnel use the SE but inspectors from the shipping authorities and insurance company are trained to check lightning conductors are in working order.  LiftPort would not get approval to carry passengers without a lightning conductor.

The sheathed air cable and the nude space cable are going to be different widths, the climbers will have to handle this.

Conclusion the balloon lifted sky platform is needed to support the lightning conductor.

Almost certainly.  See some of the things being discussed in the “Ultimate strength of CNT much smaller than expected!” thread.
http://www.liftport.com/forums/showthread.php?t=356

We can predict and prevent many problems but they are always a few we do not guess.  Hopefully the reasons SE1 broke/tore will be investigated and the cures to those problems included in SE3.  There are no plans to go back and replace the ribbon material with strips containing say the new resin, different shaped fibres and new anti-oxygen/anti-radiation coating.


Yes.  It is a race.  In many Hollywood films the heroes have to escape over a burning bridge that is falling apart.  Our sky bridge is being damaged by micro-meteors and bubbles in the glue holding it together.  The thicker starting material means that meteors have to be 10 to 100 times the size to do the same damage to SE3 and there are far fewer of them.  The use of repair robots on SE3 will make a big difference to its reliability.

Are ailerons only needed on the air climbers?  In which case they will simply be left off when the cargo is attached to the space ribbon at the Sky PLatform.

SE1 goes through some very distinct stages.  As you have noticed they probably need official names.  Some stages overlap.  The ones I can spot:

Conceptual - current stage.
Detailed planning.
Ground test of components.
Assembly of the sapling space elevator.
Gaining seed money.

Building and test of the SE1 cargo air climbers.
Building and test of the SE1 crew air climbers - human rated.
Building and test of the SE1 sky platform - human rated.
Building and launch of the SE1 sea anchor.
Launch of the sapling SE1 space elevator.
Deployment of the SE1 sapling.
Commissioning of the SE1 sky platform and sea anchor - human rated.
Attachment and commissioning of SE1 sapling to sky platform.
Upgrading of SE1.

Building the SE2 seed/sapling.


SE2 Stages

Upgrading of SE2.
Building and commissioning of the SE3 sky platform and sea anchor - human rated.
Building of the SE3 sapling.
Building of the stage 2 rocket, designed to be thrown from the SE.
Borrowing more money.

[U}SE3 Stages[/U]

Upgrading of the SE3.
Gaining approval of SE2 to carry cargo, probably from the FAA.
Testing and approval of the SE2 cargo space climbers.
Testing and approval of the SE2 cargo stage 2 rocket (excluding cabin).
Upgrading of stage 2 rocket to human rating.

Testing and approval of the SE3 cargo space climbers.
Testing and approval of the SE3 human space climbers.
Gaining approval for SE3 to carry cargo.
Gaining approval of SE3 to carry manufactures personnel such as test pilots.
Gaining approval of SE3 to carry passengers.
Building and gaining approval for stage 2 rocket's passenger and crew cabin.
Borrowing more money.

Operating the Space Elevators

Launching people and cargo into space.
Gaining orders for launches, training people, advertising and such activities.
Building SE4 etc.
Repairing and maintenance of  the current space evaluators, climbers, sea anchors and sky platforms.
Planning and building the replacements.
Making a profit and paying taxes.
Refinancing for the long term at a cheaper rate.


Do SE1 and SE2 share the same sky platform and sea anchor?
How are raw materials moved from SE1 to seed SE2?
To prevent tangling do the space elevators need to be kept a long way apart?
What happens to SE1 when SE2 can self assemble?
What happens to SE2 when SE3 can self assemble?
How are the space elevators decommissioned?

I am not in a position to give anyone a job on the Space Elevator but this is a good excuse to make a list of the Space Elevator related things that will need human testing.

Air climbers to the Sky Platform – crew.
Air climbers to the Sky Platform – passenger (a few years later).
Commissioning of air climber plus ribbon to the Sky Platform, at sea.
Space climber – crew.
Space climber – passengers including children.
Launching and receiving air climbers at Sky Platform.
Launching and receiving space climbers at Sky Platform.

Debug the launch procedures for robot climbers.
Debug the launch procedures for robot satellite throwing climbers.
Debug the launch procedures for climbers carrying people.
Commissioning of space climbers plus ribbon to the Sky Platform, at sea.

Stage 2 rocket for placing of satellites (automated but someone has to be on the Sky Platform).
Stage 2 rocket for transporting people in space.
Throwing of rockets and satellites from climbers – mechanism, reliable timing and very accurate height determination.

Sky Platform's balloons and their controls.
Sky Platform's crew cabin.
Sky Platform's passenger departure lounge (SE3+).
Sky Platform's cargo handling machines and their controls.
Sky Platform's power generation system.
Sky Platform's communications equipment.
Sky Platform's floor and surrounding barrier – we do not want people slipping or falling out.
Sky Platform's tether.
Sky Platform's tow ribbon.
Failure of tether – tow ribbon takes over automatically.
Failure of a balloon – Sky Platform stays in the sky, possibly at a lower height.

Continuing repair of the Sky Platform.
Continuing repair of the tether.
Continuing repair of space cable.

Mini spacesuit – the air is too thin for humans at the operating height of the Sky Platform.  The operators need to perform outdoor task like the opening of the solar panels on satellites.

Raising and lowering of Sky Platform.
Commissioning of the sea anchor.
Moving of the SE and sea anchor – may involve several ships.
Loading cargo, including climbers, from boats onto the sea anchor.
Loading passengers and crew onto the sea anchor from boats.
Loading passengers and crew from the sea anchor to boats.
Same for helicopters.
Loading of air climbers and cargo (including space climbers) onto tether.
Adding of fuel and coolant to climbers and satellites.
Unloading of returned air climbers and their cargos.
Debugging of sea anchor procedures.

Ensuring the space debris tracking equipment works.
Debugging procedures for moving space elevator to avoid space debris.

Anyone got any comments or additions to the list?